GT4 Dampers

Scaff · Apr 7, 2006

sucahyo
Thanks . Ok, so that means damper 10 is hard, it's clear that GT2 and GT4 behave differently now.

Yep, I am so glad that you agree, higher damper values in GT4 are harder.

As for GT2 well thats a totally different discussion (and one for the GT2 Forum rather than here).

sucahyo
Ok. BTW, do load transfer has the same meaning as weight transfer?

In the context of what we are talking about here then yes they are. Strictly speaking the 'correct' term is load transfer, so thats my fault for confusing the issue.

sucahyo
Agree, tuning damper should be done after spring rate tuning.

It should, but I have to admit that I don't always do it that way around. I know I should, but with the defualt values for FC set-up being so stiff to begin with I often find I have to lower them to around about 5/5 (depending on the car) before I can get a feel for the springs. This is because often the over-damping effect of the high default value can mask the true effect of the spring rate.

sucahyo
Yes, I experience that changing slip threshold in GT2 really change how the car handle in relation with weight transfer. Not to mention a more pronounce understeer.

BTW, do you know how the relation between lateral grip and longitudinal grip supposed to be for real life normal tire? lateral grip = 2 X longitudinal grip?

Oh god thats about the nastiest question I've ever been asked. If you think that dampers get complicated then think again, tyre tech is one of the single most complex and difficult topics to cover.

Outside of tyre manufacturing companies and race teams little data is avaliable about the relationship between lateral and longitudinal grip. And most tyre companies and race teams guard the data they have very well.

This should help, its an extract from an excellent book called "The Racing & High Performance Tire", which was published in the Jan 2004 issue of Sports Car magazine and then on the web (which is this link).

Tire Behaviour

In that you will find a section called Combined Forces which looks at the relationship between the two.

The difficultly in answering your question directly is that a tyre has to be moving to encounter lateral forces, which means that it will also be encountering longitudinal forces. A straight ratio of one to the other is very difficult to either predict or calculate.

Don't take the two graphes in the article as anything other than a general indicator of what could happen.

In my mind this is the biggest problem that developers of driving/racing sims are coming up against now. Recreating the forces that a tyre undergoes is very, very difficult and complex for a single tyre. Now imagine having to do it for four of them!!!

You see (and this you can get from the graphs) the ratio between lateral and longitudinal grip levels (or slip angle and slip percentage to be correct) do not exist at a fixed ratio, but rather vary accoring to the given value of one or the other.

In short tyres are the arguably the single most important componant on a car, and also one of the most complex.

You can find a lot more info about the importance of tyres in the GT4 & Brakes thread. The reason being that brakes don't stop your car, tyres do.

Don't argue with the above statement - read this

Tyre tech is actually one of my favorite subjects to discuss.

Regards

Scaff

Dave_George · Apr 7, 2006

Scaff
The reason being that brakes don't stop your car, tyres do.

Tyre tech is actually one of my favorite subjects to discuss.

Regards

Scaff

Hi Scaff,

Just a quick question on the above point, EVO mag this month have a group test with the Evo 9 vs Subaru WRX vs BMW 330 vs Vectra...

In one section related to track times they mention that the Evos brakes started to suffer after a full lap, not something I remember the Evo suffering with before, this was the FQ320 with road tyres not the 340 which has track biased rubber, would the 340 be easier on its brakes because its tyres are so much grippier?? Sorry if its off topic I just wondered when I saw your reply above

regards

Dave

Scaff · Apr 7, 2006

Dave_George
Hi Scaff,

Just a quick question on the above point, EVO mag this month have a group test with the Evo 9 vs Subaru WRX vs BMW 330 vs Vectra...

In one section related to track times they mention that the Evos brakes started to suffer after a full lap, not something I remember the Evo suffering with before, this was the FQ320 with road tyres not the 340 which has track biased rubber, would the 340 be easier on its brakes because its tyres are so much grippier?? Sorry if its off topic I just wondered when I saw your reply above

regards

Dave

I think thats last months Evo (this months has the huge car shoot-out) which I've given to my Dad, damn my generosity now I can't check everything.

Now I've just been on the Mitsu website and the entire Evo range have the same braking system, discs and calipers and all run the same tyres as standard (Advan A046 all round) and the same size.

Heres a side by side spec compo between the FQ-320 and FQ-340

So its not down to the tyres, it could just be down to the particular car on the day, if the pads were old or had not been bedded in correctly.

On the tyre front, grippier tyres would actually make it more likely that the brakes would fade.

Think about it this wasy, the amount of work you are going to ask the pads and discs to do is determined by the stopping potential of the tyres. The more work you ask them to do the more likely they are to over-heat and fade.

If the track rubber has a maximum stopping potential of 1.2g and the road rubber has a maximum stopping potential of 1g, then the track rubber is going to be asking more of the discs and pads if we want to exploit the tyres full potential.

Fitting grippier rubber will always stop you quicker, but it may well ask more of your brakes than they can give, thats when its time to start looking at a brake upgrade.

Regards

Scaff

sucahyo · Apr 8, 2006

Scaff
Yep, I am so glad that you agree, higher damper values in GT4 are harder.

Now that I think GT4 damper 10 is stiffest, I have some few changes in my tuning.

Facts:
- Skip barber: "Expect that the shock settings for bumpy racetracks will have to be softer in order to allow the suspension to move fast enough to keep the tyres in contact with the track surface."
- Based on many tests, damper 10 is too hard even for hardest spring rate

For bumpy track:
My current damper knowledge tell me that if spring rate is soft I better use soft damper, if spring rate is hard I can use stiff damper but softer is better. If damper 10 is too hard even for stiff spring then using damper 10 for soft spring is highly unrecommended.
My logic, if damper 10 have the power to restrict the stiffest spring rate, then using damper 10 on soft spring will overwhelm the spring power, make it unable to move properly at all.

So, the appropriate damper tuning is like this:
- for spring rate ranging from 4-8, damper 2 is the max we can use
- for spring rate ranging from 8-12, damper 4 is the max we can use
- for spring rate ranging from 12-16, damper 6 is the max we can use
- for spring rate ranging from 16-20, damper 8 is the max we can use

On all this case, using max setting is unadvisable, so is better to use half value, that:
- for spring rate ranging from 4-8, damper 1 is the only choice we have
- for spring rate ranging from 8-12, we can use damper 1 and 2
- for spring rate ranging from 12-16, we can use damper 1,2 and 3
- for spring rate ranging from 16-20, we can use damper 1,2,3 and 4

Since stiff damper give more problem to the lighter car, this should mean we should reduce the damper use again. So for extreme case like caterham or elise, we have to use damper 1 only.

For smooth track:
We can use more damper range, as bump wouldn't cause much problem we can use higher damper value.

This is reverse of what I do in GT2, so I think it would be hard to adjust my tuning to it. In GT2 I limit the damper to low value for stiffer spring rate.
If using damper 10 actually allow soft spring to move when it can prevent stiff spring to move, I will rethink my tuning method again (and brainwash my logic again).
Do you think this tuning method is rubish or good enough?

Scaff
In the context of what we are talking about here then yes they are. Strictly speaking the 'correct' term is load transfer, so thats my fault for confusing the issue.

Ok. I am trying to understand this:

skip barber
A stiffer bump setting slows down the motion on its corner ans speeds up the load transfer. A softer bump setting does the opposite - it allows the suspension to move faster and spreads the changes in loading out over a longer period of time. The same is true of rebound. Stiff re-bound settings will force the suspension system to move more slowly when loads are removed from its corner of the car, but the unloading of the contact patch will be more abrupt. Softer rebound settings allow the suspension to move more quickly and the unloading of the contact patch happens more gradually

I think I use this reference for my tuning, from Skip barber too.
"The greater the load transferred to the outside, the more the CF of the loaded tires will suffer. Less load transfer means a higher overall CF for all four tires and, consequently, greater traction and cornering speed" (same is true for braking.... but replace slip angle with % slip)."

If less load transfer equal to more grip, using soft damper is better. I am still confuse though. So when using softer damper:
- less load transfer, better tire grip?
- more body roll, more snappy handling?

So we must compromise between tire grip and unconnected feeling?
Since damper 1 (stiff) never give problem to handling, I think it's better to use 1 damper all the time, at all spring combination, unless the handling is too unconnected. In GT2 using 10 can give problem at stiff spring, so when using stiff spring I need to lower the damper.

Scaff
This is because often the over-damping effect of the high default value can mask the true effect of the spring rate.

Yes.

Scaff
Oh god thats about the nastiest question I've ever been asked. If you think that dampers get complicated then think again, tyre tech is one of the single most complex and difficult topics to cover.

Outside of tyre manufacturing companies and race teams little data is avaliable about the relationship between lateral and longitudinal grip. And most tyre companies and race teams guard the data they have very well.

that is way too complex :dopey:

. I don't think can't say anything

. I guess I should go back to experiment methode then

. Seeing that brake and acceleration have different tire reaction, I guess I miss the brake slip variable (I find it but don't know what it was).

Dave_George · Apr 8, 2006

Scaff
I think thats last months Evo (this months has the huge car shoot-out) which I've given to my Dad, damn my generosity now I can't check everything.

Now I've just been on the Mitsu website and the entire Evo range have the same braking system, discs and calipers and all run the same tyres as standard (Advan A046 all round) and the same size.

Heres a side by side spec compo between the FQ-320 and FQ-340

So its not down to the tyres, it could just be down to the particular car on the day, if the pads were old or had not been bedded in correctly.

On the tyre front, grippier tyres would actually make it more likely that the brakes would fade.

Think about it this wasy, the amount of work you are going to ask the pads and discs to do is determined by the stopping potential of the tyres. The more work you ask them to do the more likely they are to over-heat and fade.

If the track rubber has a maximum stopping potential of 1.2g and the road rubber has a maximum stopping potential of 1g, then the track rubber is going to be asking more of the discs and pads if we want to exploit the tyres full potential.

Fitting grippier rubber will always stop you quicker, but it may well ask more of your brakes than they can give, thats when its time to start looking at a brake upgrade.

Regards

Scaff

Cheers for that Scaff, could have been last months Evo as I dont get it too regularly now....makes me want nice cars too much...

Dave

Scaff · Apr 8, 2006

sucahyo
Now that I think GT4 damper 10 is stiffest, I have some few changes in my tuning.

*snip*

Do you think this tuning method is rubish or good enough?

As a base point to begin tuning if the above works for you then use it.

I personally prefer (as you know) a more 'feel' based approach to tuning, but the above details seem to be a fine point to start as it matches spring rate to damper, and accounts for vehicle weight.

The only thing I would personally warn against is getting to fixated on tables and exact matched values, by all means use them as a tool to indicate a starting point, but don't let them force you to use a certain value.

sucahyo
I think I use this reference for my tuning, from Skip barber too.
"The greater the load transferred to the outside, the more the CF of the loaded tires will suffer. Less load transfer means a higher overall CF for all four tires and, consequently, greater traction and cornering speed" (same is true for braking.... but replace slip angle with % slip)."

If less load transfer equal to more grip, using soft damper is better. I am still confuse though. So when using softer damper:
- less load transfer, better tire grip?
- more body roll, more snappy handling?

So we must compromise between tire grip and unconnected feeling?
Since damper 1 (stiff) never give problem to handling, I think it's better to use 1 damper all the time, at all spring combination, unless the handling is too unconnected. In GT2 using 10 can give problem at stiff spring, so when using stiff spring I need to lower the damper.

OK we just need to clarify a few things here.

First go back and read Greyout's guide to weight transfer, either by clicking on this link or reading pages 14 to 16 of part 1 of my tuning guides.

Now keeping that in mind remember that you can't use spring rates, damper values, etc to change the amount of load transfer that occurs front to rear. However spring rates (and if stiff enough to limit springs then dampers as well) can change how that load is distributed between the two front (and rear) tyres.

This is however a relationship between the front and rear of the car, so for example a car with a softer front end that rear would allow the load to be more evenly distributed between the two front tyre, but the stiffer rear would ditribute more of the load to one of the rear tyres. The overall balance of the car would (in this case) be oversteer.

Two problems can occur with this however, as the suspension reacts quicker to the load transfer, the effect of that transfer to the contact patch is slowed down which can result in sluggish handling and poor initial response.

The second problem is that if you go too soft (in springs and dampers) for the cars weight, then you have to run at a higher ride height (to avoid bottoming out through greater body-roll) which raises the centre of gravity and increases the amount of load transfer.

You see in GT4 we can only do a few things to change the amount of load that is transfered, these are adjusting the ride height setting, adjusting the balast and taking the weight reduction modification. No other setting will change the amount of load transfered, just how it is distributed.

sucahyo
that is way too complex . I don't think can't say anything . I guess I should go back to experiment methode then . Seeing that brake and acceleration have different tire reaction, I guess I miss the brake slip variable (I find it but don't know what it was).

Yep very, very complex and keep in mind that the article I linked to was the simple and basic stuff, it gets realy complex.

Dave_George
Cheers for that Scaff, could have been last months Evo as I dont get it too regularly now....makes me want nice cars too much...

Dave

Don't worry about it, I don't know if the new issue is on the shelves yet (I have a subscription and it normally arives a few days early).

Makes me want nice new cars as well, but I just love the photography and writing so much I have to get it.

Regards

Scaff

sucahyo · Apr 11, 2006

Scaff
The only thing I would personally warn against is getting to fixated on tables and exact matched values, by all means use them as a tool to indicate a starting point, but don't let them force you to use a certain value.

Ok, I use table to help me think the correct way to tune. The table is match by experiment too.

Scaff
You see in GT4 we can only do a few things to change the amount of load that is transfered, these are adjusting the ride height setting, adjusting the balast and taking the weight reduction modification. No other setting will change the amount of load transfered, just how it is distributed.

Ok. Thanks, I need to learn more

.

Scaff
Yep very, very complex and keep in mind that the article I linked to was the simple and basic stuff, it gets realy complex.

, I am glad that I don't have to know all that.

sucahyo · Apr 12, 2006

Yesterday I have time to play around with Caterham Fireblade in Deep Forest, free run:

Stock with FC suspension:
Spring rate - 5.0/5.0
Ride height - 90/90
Camber - 0.0/0.0
Toe - 0/0
Stabilizer - 1/1
Balast : 0/+50

d-high = damper 10/10 10/10
d-low = damper 1/1 1/1

What I experience:
I drive with d-high first. Since I am not so good in driving, I drive trough the grass often. When the car passing the side rumble strip to go back to the road the car become very lively. It bounce around few time before it stop.
On replay, same with Scaff, I don't notice much movement from suspension.

Next is d-low. This time I notice that the car bounce a lot less on the road, :confused:

. On replay I see some suspension movement.

Curious with less bouncing using d-low, I try again with d-high. And I notice that in grass d-high would bouncing less, where in tarmac d-high would bouncing more, :confused:

.
On replay I notice that the front wheel is vibrating when driving through grass. If only the front left wheel touching the grass, only the front left wheel that vibrate. Not only on the grass, on some part of the tarmac the wheel also vibrate momentarily.

Seeing this vibration, I drive again with d-low. On replay, this time I notice that in grass the wheel is also vibrate, but not as much as d-high. And on the grass the wheel vibrate only momentarily because it imediately jump around in grass. The wheel never vibrate in tarmac, it just show slow damper movement which is not exist in d-high.

So,
d-low jump more in grass, d-high jump more in tarmac.
d-low vibrate slower in grass, d-high vibrate more in grass.
d-low never vibrate in tarmac, d-high sometimes vibrate in tarmac.

This make me think that d-high is softer again :confused:

............

Mt. Lynx · Apr 12, 2006

sucahyo
Yesterday I have time to play around with Caterham Fireblade in Deep Forest, free run:

Stock with FC suspension:
Spring rate - 5.0/5.0
Ride height - 90/90
Camber - 0.0/0.0
Toe - 0/0
Stabilizer - 1/1
Balast : 0/+50

d-high = damper 10/10 10/10
d-low = damper 1/1 1/1

What I experience:
I drive with d-high first. Since I am not so good in driving, I drive trough the grass often. When the car passing the side rumble strip to go back to the road the car become very lively. It bounce around few time before it stop.
On replay, same with Scaff, I don't notice much movement from suspension.

Next is d-low. This time I notice that the car bounce a lot less on the road, . On replay I see some suspension movement.

Curious with less bouncing using d-low, I try again with d-high. And I notice that in grass d-high would bouncing less, where in tarmac d-high would bouncing more, .
On replay I notice that the front wheel is vibrating when driving through grass. If only the front left wheel touching the grass, only the front left wheel that vibrate. Not only on the grass, on some part of the tarmac the wheel also vibrate momentarily.

Seeing this vibration, I drive again with d-low. On replay, this time I notice that in grass the wheel is also vibrate, but not as much as d-high. And on the grass the wheel vibrate only momentarily because it imediately jump around in grass. The wheel never vibrate in tarmac, it just show slow damper movement which is not exist in d-high.

So,
d-low jump more in grass, d-high jump more in tarmac.
d-low vibrate slower in grass, d-high vibrate more in grass.
d-low never vibrate in tarmac, d-high sometimes vibrate in tarmac.

This make me think that d-high is softer again ............

How can you think that?? Please elaborate on your thoughts on the matter! What you describe are exactly spot on for d-high=hard and d-low=soft!

sucahyo · Apr 12, 2006

Team666
How can you think that?? Please elaborate on your thoughts on the matter! What you describe are exactly spot on for d-high=hard and d-low=soft!

The reason I think d-high is softer is:

A stiffer bump setting slows down the motion on its corner ans speeds up the load transfer. A softer bump setting does the opposite - it allows the suspension to move faster and spreads the changes in loading out over a longer period of time.
softer damper allow more suspension movement and allow more suspension speed, so, more vibration in grass and some place in tarmac, and more faster reaction to the road at tarmac make the suspension movement hard to see.
softer damper do not silence spring movement much, it allow movement at a longer time, so, more bouncing on tarmac.
stiffer damper restrict suspension movement and restrict suspension speed, so, less vibration in grass but also make the suspension unable to follow grass countour correctly, making it more unstable in grass. slower suspension reaction to the road at tarmac make us able to easily notice the suspension movement.
stiffer damper silence spring movement more, it restrict movement at a shorter time, so, less bouncing on tarmac.

So, it only make sense for me if d-high is softer than d-low.
It follow the road contour much faster than d-low. The reason why we can not see more suspension movement in d-high is because the suspension move too fast that our eyes have difficulty to follow it.

T4 GTR · Apr 12, 2006

Hmmm...
Thats strange the way that reacts, you would think it would be the other way round. Could this be due to design fault. I have a good knowledge of racing as I drive prototypes but I always thought it was different.

sucahyo · Apr 13, 2006

T4 GTR
Hmmm...
Thats strange the way that reacts, you would think it would be the other way round. Could this be due to design fault. I have a good knowledge of racing as I drive prototypes but I always thought it was different.

What an awesome experience :drool:

.
Judging from car reaction, without assuming which damper is stiff or soft, can you tell your opinion of what make the car do something like that?

Scaff · Apr 13, 2006

@sucahyo

A very quick one as I am about to get on a plane to fly back from Italy.

Once again your entire piece is based on visual only information, what about feel?

I'm sorry to say but I also dispute what you say in regardto the visual info itself, the range of suspension movement on the lower damper values is 'clearly' greater (and faster) than that of the higher settings.

The higher damper setting are restricting the range of the spring to such a degree that spring travel is limited and the reaction of the suspension is slowed.

Don't look at just the wheel (as this will move if the entire car moves) but at the movement of the suspension wishbones themselves.

And all that is without the feel and noise.

Regards

Scaff (fed up with work and travel)

sucahyo · Apr 15, 2006

Scaff
Once again your entire piece is based on visual only information, what about feel?

About feel:
- since I turn off the (inaccurate) force feedback in the DS2, I don't know the buzz difference
- on grass using d-low definitely more unstable than d-high
- for bouncing after go back to the road, I only see it happen from rear view, d-high bouncing periode is longer than d-low, I can't describe the feel.
- when drifting around, d-high feel more planted to the road, I can't feel the wallowing difference.

Scaff
I'm sorry to say but I also dispute what you say in regardto the visual info itself, the range of suspension movement on the lower damper values is 'clearly' greater (and faster) than that of the higher settings.

Yes, I notice that on tarmac, d-low shown suspension movement where d-high doesn't. But as I don't know how to replay in slow motion I can not be sure that the suspension do not move at all. I still don't have chance to record this in video too.
What make me curious and assume that suspension moving very fast so eyes can't see is the jiggling/vibration in some part of the tarmac. If the vibration is hard to notice (in 21" screen), noticing suspension movement surely be harder. If we can make video for it, putting red line mark on zero travel, we can surely notice suspension movement easier.
BTW, I see this from in front of car camera replay.

Scaff
The higher damper setting are restricting the range of the spring to such a degree that spring travel is limited and the reaction of the suspension is slowed.

Yes. I agree. About slowed down, d-low have slower vibration compare to d-high in grass.

Scaff
Don't look at just the wheel (as this will move if the entire car moves) but at the movement of the suspension wishbones themselves.

I did. The most noticable difference is when I make only the right wheel is on the grass where the left wheel is on the tarmac. The right wheel noticably vibrate more using d-high, and slower using d-low. The car body do not vibrate at all, the left wheel is stable.

Scaff
And all that is without the feel and noise.

I can't feel that

, and I will try to listen the sound next time.

Scaff · Apr 16, 2006

sucahyo
About feel:
- since I turn off the (inaccurate) force feedback in the DS2, I don't know the buzz difference
- on grass using d-low definitely more unstable than d-high
- for bouncing after go back to the road, I only see it happen from rear view, d-high bouncing periode is longer than d-low, I can't describe the feel.
- when drifting around, d-high feel more planted to the road, I can't feel the wallowing difference.

Umm the DS2 is not (as far as I'm aware) a force feedback device, rumble only. It is however possiable to feel the difference between the two settings with the DS2, its just better with a DFP.

In regard to grass, I don't find either setting to be great on the grass, but then again I would not expect many suspension settings to be that great for a 400-500 kilo race car at 60mph+ on grass.

In regard to the 'car' bouncing more on return to tarmac then yes D high settings do cause the 'car' to jump more. Now look at the actual suspension itself, it hardly moves, the 'car' jumping is a result of the force being dirrectly transferred through the suspension and onto the cars chassis.

sucahyo
Yes, I notice that on tarmac, d-low shown suspension movement where d-high doesn't. But as I don't know how to replay in slow motion I can not be sure that the suspension do not move at all. I still don't have chance to record this in video too.
What make me curious and assume that suspension moving very fast so eyes can't see is the jiggling/vibration in some part of the tarmac. If the vibration is hard to notice (in 21" screen), noticing suspension movement surely be harder. If we can make video for it, putting red line mark on zero travel, we can surely notice suspension movement easier.
BTW, I see this from in front of car camera replay.

Your first sentence describes it well, but I would not say that no suspension movement can be seen with the D-high settings, but it is clearly reduced and slower.

The assumption that the suspension is moving too fast to be seen is just that, an assumption and one of the damgers of just looking at the tyres. You are assuming that the visual side of GT4 is perfect and thats a flawed assumption to make. Hence the reason I am looking at all aspects visual, feel and noise.

Stop looking at the wheels/tyres and look at the actual exposed front suspension of the Caterham (as I described in my post above), it can be clearly seen to move with both a greater range and react faster with D low settings, while D high settings restrict the movement range and slow down the reactions that are present.

sucahyo
Yes. I agree. About slowed down, d-low have slower vibration compare to d-high in grass.

Sorry I don't agree with that at all, as I have just explained above.

sucahyo
I did. The most noticable difference is when I make only the right wheel is on the grass where the left wheel is on the tarmac. The right wheel noticably vibrate more using d-high, and slower using d-low. The car body do not vibrate at all, the left wheel is stable.

Stop just looking at the damn wheels/tyres, look at the movement of teh suspension wishbones themselves, particularly under load transfer, when braking into the first left hand corner at Deep Forest the difference in range of movement and speed of reaction is clear to see.

sucahyo
I can't feel that , and I will try to listen the sound next time.

I don't know why you can't feel this, and also why (despite me mentioning it countless times) you are still looking at limit visual information only.

In closing every single test that I have now put up here (described in detail) supports D low being softer and D high being firmer; the numerous Caterham tests, the Intergra test, the Dodge Charger test, all of them. In addition these have always looked at all aspect of the run, from feel, noise, handling and visual; all of which support the same thing. In addition all of the other people who have commented on this subject have agreed with the results.

Everytime this thread 'pops' up again I run a new set of tests, over and over again and every single time it simply re-enforces that D-low is softer and D-high is firmer.

I must confess that some of your reasoning is now starting to look a little weak, as an example the lastest one is that tiny wheel vibration are the suspension reacting too fast for the human eye to see!

Sorry but it is far more likely that this is simply the GT4 graphics engine; as the actual movement of the suspension system itself, the way the car reacts and feels along with the noise all point to the same thing.

I too saw them and its the reason I picked the Caterham, as it allows the whole front suspension to be seen and observered. Its also the reason I do not use a single piece of information to test a theory, quite simply it can lead you to false conclusions.

Regards

Scaff

sucahyo · Apr 17, 2006

For easier reference:

A stiffer bump setting slows down the motion on its corner ans speeds up the load transfer. A softer bump setting does the opposite - it allows the suspension to move faster and spreads the changes in loading out over a longer period of time. The same is true of rebound. Stiff re-bound settings will force the suspension system to move more slowly when loads are removed from its corner of the car, but the unloading of the contact patch will be more abrupt. Softer rebound settings allow the suspension to move more quickly and the unloading of the contact patch happens more gradually
The suspension system must also reacts to track irregularlities - namely bumps. On a very smooth racetrack, you can get away with using stiffer bump and rebound settings, but remember that stiff settings slow down the suspension movement by having higher resistance to motion.
The downside of this maneuver is that if the suspension has to move fast to absorb a bump or series of bumps, it may not be able to react fast enough to keep the tires in contact with the road. Tires that spend half their time in the air don't provide much grip. Expect that the shock settings for bumpy racetracks will have to be softer in order to allow the suspension to move fast enough to keep the tires in contact with the track surface
Shock absorbers or more correctly Dampers, have the primary function of helping to control the energy stored up by the springs. A spring is a remarkable depository of energy. When the spring is compressed by a bump or a change in load on the spring, it stores the energy of the initial motion and feeds most of it back in the opposite direction. Without control, the spring would go through a number of cycles of compression and extending in response to its first deflection, losing a little energy with each cycle.
Ultimately, the shock setting doesn't determine how much load gets to the tyre or how much the suspension moves moves in response to the load. It alters the speed with which the load gets to the contact patch and the speed with which the suspension moves in response to the loads fed into it.
Expect that the shock settings for bumpy racetracks will have to be softer in order to allow the suspension to move fast enough to keep the tyres in contact with the track surface.

Scaff
Umm the DS2 is not (as far as I'm aware) a force feedback device, rumble only. It is however possiable to feel the difference between the two settings with the DS2, its just better with a DFP.

Ok, I mean rumble.

Scaff
In regard to grass, I don't find either setting to be great on the grass, but then again I would not expect many suspension settings to be that great for a 400-500 kilo race car at 60mph+ on grass.

Try with less than 30mph. You don't feel any difference in handling for both? I do, d-low definitely better at grass.
reference 2, 3 and 6.

Yesterday I did the run again with 15/15 spring rate, bellow 30mph. d-high follow the grass bump better too. d-low has noticably lower wheel moement.

Scaff
In regard to the 'car' bouncing more on return to tarmac then yes D high settings do cause the 'car' to jump more. Now look at the actual suspension itself, it hardly moves, the 'car' jumping is a result of the force being dirrectly transferred through the suspension and onto the cars chassis.

I am lost, what is the difference?
reference 1 and 4.

IMO, The car bouncing more because faster response time, less restricted spring and spreading load over longer period of time..

Scaff
Your first sentence describes it well, but I would not say that no suspension movement can be seen with the D-high settings, but it is clearly reduced and slower.

I tried again with 15/15 spring rate, I am not sure d-high is slower. it seems d-low is slower.

Scaff
The assumption that the suspension is moving too fast to be seen is just that, an assumption and one of the damgers of just looking at the tyres. You are assuming that the visual side of GT4 is perfect and thats a flawed assumption to make. Hence the reason I am looking at all aspects visual, feel and noise.

In other word, you say GT4 visual physics is flawed? Bug or design error (these two is different)?

Scaff
Stop looking at the wheels/tyres and look at the actual exposed front suspension of the Caterham (as I described in my post above), it can be clearly seen to move with both a greater range and react faster with D low settings, while D high settings restrict the movement range and slow down the reactions that are present.

Why? Are you saying reference 3 is incorrect? I assume it means suspension move along with the tire.
Are you saying the wishbone movement is correct and tire movement isn't?
Try again with stiffer spring rate.

Scaff
Stop just looking at the damn wheels/tyres, look at the movement of teh suspension wishbones themselves, particularly under load transfer, when braking into the first left hand corner at Deep Forest the difference in range of movement and speed of reaction is clear to see.

I don't have that skill, I can't consistently brake at the same place. I guess I will see how B-Spec drive it next time.
My current assumption, If the car already dive when we realease the throttle, the car won't dive more when we hit the brake.

Scaff
I don't know why you can't feel this, and also why (despite me mentioning it countless times) you are still looking at limit visual information only.

What I feel is different from yours. Why you keep saying visual is unreliable? I thought when you say your integra jump lower using d-low you believe GT4 visual is correct? If you say vibration is visual mistakes, direct jump after bump is also visual mistakes.

Scaff
In closing every single test that I have now put up here (described in detail) supports D low being softer and D high being firmer; the numerous Caterham tests, the Intergra test, the Dodge Charger test, all of them. In addition these have always looat all aspect of the run, from feel, noise, handling and visual; all of which support the same thing. In addition all of the other people who have commented on this subject have agreed with the results.

After I testing Caterham my self, I must say that isn't the case. This is what I curently confirm with minimum FC suspension spring rate.
- Caterham, d-low has slower suspension movement than d-high.
- RUF BTR2, Mustang GT and Falken GT-R tuning, car feel slugish or snappy with d-high.
- Car nodding in 6 of my 300mph car, whatever make the car nodding, it is reduce / slower if we use d-low. The most confincing (for me) is when I try using different damper combination. more front rebound reduce nose up speed. and more front bound reduce nose down speed.

Scaff
Everytime this thread 'pops' up again I run a new set of tests, over and over again and every single time it simply re-enforces that D-low is softer and D-high is firmer.

Same here.

Scaff
I must confess that some of your reasoning is now starting to look a little weak, as an example the lastest one is that tiny wheel vibration are the suspension reacting too fast for the human eye to see!

I have my reason, I say that because noticing wheel vibration from 14" screen is definitely very hard for me. Curiously, using 15/15 spring rate make the vibration easier to see.

Scaff
I too saw them and its the reason I picked the Caterham, as it allows the whole front suspension to be seen and observered. Its also the reason I do not use a single piece of information to test a theory, quite simply it can lead you to false conclusions.

And if I have different result?

Mt. Lynx · Apr 17, 2006

sucahyo
And if I have different result?

Well, if you are the only one getting different results, the possibility of you being wrong, and everyone else right, is pretty high. 💡

sucahyo · Apr 17, 2006

Team666
Well, if you are the only one getting different results, the possibility of you being wrong, and everyone else right, is pretty high. 💡

Either that or they just don't care

. I mean, thing like this is rarely discussed. If you find some weird thing you assume it's just another glitch and thinking lightly the word "funny, it shouldn't be like that"

.
Should we believe everything PD want us to believe ?
Just like PD fool us into thinking that 2.0/1.0 camber is the best combination because every road car with FC suspension have that value as default. And yet PD use 0.0/0.0 camber for every stock car, which is I think very unresponsible 👎. If stock car has softer spring than FC suspension why they don't use camber value like 4.0/2.0 for it :confused:

?
Why they do that :confused:

?
or Why they reverse the damper :confused:

?

Dave_George · Apr 17, 2006

sucahyo
Should we believe everything PD want us to believe ?
Just like PD fool us into thinking that 2.0/1.0 camber is the best combination because every road car with FC suspension have that value as default.

I'm not sure its a case of us believing everything P.D want us to believe, more, on our part to accept that GT4 is not and cannot be perfect in simulating real cars physics and behaviour.

I have never felt "Fooled" into thinking 2.0/1.0 is the best combination of camber, All of the default values for FC suspension need a bit of tweaking when setting up a car, they could have used default values of 0 for everything I suppose, but then you would get the people who cant or dont want to tune cars moaning that they had to adjust everything. PD cannot please all of the people all of the time.

David

Scaff · Apr 17, 2006

sucahyo
Either that or they just don't care . I mean, thing like this is rarely discussed. If you find some weird thing you assume it's just another glitch and thinking lightly the word "funny, it shouldn't be like that" .
Should we believe everything PD want us to believe ?
Just like PD fool us into thinking that 2.0/1.0 camber is the best combination because every road car with FC suspension have that value as default. And yet PD use 0.0/0.0 camber for every stock car, which is I think very unresponsible 👎. If stock car has softer spring than FC suspension why they don't use camber value like 4.0/2.0 for it ?
Why they do that ?
or Why they reverse the damper ?

You're post above I will have to get back to, as I'm leaving for the airport soon (and my damn car has a flat battery).

I don't think anyone here is folled by any of the default settings into believeing they are the 'best' (aprt it seems from yourself).

The stock camber value of 0/0 is not that far from reality, do you honestly think that road cars are set-up to maximise the cornering potential of the tyres at the expense of straightline stability and braking? Of course they are not, in fact its no unheard of for road cars to run a small degree of positive front camber to actively encourage understeer to develop. Its safer that way for the average driver.

The problem here I am afraid is not PDs, but yours. Again you are making assumptions that are flawed and come from a poor understanding of real world settings and applications.

In regard to the dampers being reversed, sorry but you are wrong, my reply to that I will write at the airport, so it should be up in a day or two.

Regards

Scaff

Mt. Lynx · Apr 17, 2006

I have never felt that any value PD assignes for any car is really optimized. They are at the most a guidline, but I usually end up changing most, or all, settings.
As for camber, Scaff is right in what he says, and he - if anyone here - knows this, due to his experience from the car industry.

And the damper values are not reversed!

sucahyo · Apr 18, 2006

Dave_George
I'm not sure its a case of us believing everything P.D want us to believe, more, on our part to accept that GT4 is not and cannot be perfect in simulating real cars physics and behaviour.

I see, we just have different way of believing how real life is simulated then

.

Dave_George
I have never felt "Fooled" into thinking 2.0/1.0 is the best combination of camber, All of the default values for FC suspension need a bit of tweaking when setting up a car, they could have used default values of 0 for everything I suppose, but then you would get the people who cant or dont want to tune cars moaning that they had to adjust everything.

That's good 👍. I prefer the moaning solution

.

Dave_George
PD cannot please all of the people all of the time.

Ok, I still love it though

.

Scaff
I don't think anyone here is folled by any of the default settings into believeing they are the 'best' (aprt it seems from yourself).

Yeah

, when I found out that GT2 hacked damper is soft I start suspecting any other design anomaly too

. I am so mad back then

.
My opinion back before I assume 10 is soft:
"Conclusion
On 20/20 spring rate opti club is jumpy. It will jump again after landing (I call this rejump). Different suspension setting affect the rejump.

Reducing spring rate is the best way to reduce rejump,
more bound damper will make the car easier to rejump,
more rebound damper make the car less likely to rejump but it transfer the force to other wheel (it make the other part bounce),
more downforce can reduce rejump.

Rank based on my easiest to drive feeling (on jumpy ot bouncy road):
1. Less spring rate
2. More downforce
3. More rebound damping
4. Reference
5. More bound damping"

Back then I already conclude that d-high drive better than d-low, despite my current assumption that 10 is softest

. And I consider this conclusion still valid now

.

After this I try using hacked damper just to see how far the car can jump, but I found out that using 20 damper make the go boing boing non stop so much that attempting to drive the car to the jump point is very hard

. this is when I came to conclusion that damper 10 is soft and start this thread too

.

Scaff
The stock camber value of 0/0 is not that far from reality, do you honestly think that road cars are set-up to maximise the cornering potential of the tyres at the expense of straightline stability and braking? Of course they are not, in fact its no unheard of for road cars to run a small degree of positive front camber to actively encourage understeer to develop. Its safer that way for the average driver.

Yes, I am not saying that 0/0 camber is incorrect for stock car (I even open old hayes book to check before posting that

) , but I am saying using 2.0/1.0 for default value for FC suspension (1/0.5 sport?) is irresponsible. How come they use smaller camber for softer suspension is what I curious about. Do they programmed camber to be reversed too? ( :lol:

it cross my mind too, but camber seems ok

).

Scaff
The problem here I am afraid is not PDs, but yours. Again you are making assumptions that are flawed and come from a poor understanding of real world settings and applications.

Well, I make my assumption based from hacker perspective first and I learn what the proper real world application from you all, and still think damper 10 is soft

.

Scaff
In regard to the dampers being reversed, sorry but you are wrong, my reply to that I will write at the airport, so it should be up in a day or two.

Ok.

Team666
I have never felt that any value PD assignes for any car is really optimized. They are at the most a guidline, but I usually end up changing most, or all, settings.

👍.

Team666
As for camber, Scaff is right in what he says, and he - if anyone here - knows this, due to his experience from the car industry.

I agree to that too

.

Team666
And the damper values are not reversed!

Scaff · Apr 18, 2006

sucahyo
For easier reference:

1. A stiffer bump setting slows down the motion on its corner ans speeds up the load transfer. A softer bump setting does the opposite - it allows the suspension to move faster and spreads the changes in loading out over a longer period of time. The same is true of rebound. Stiff re-bound settings will force the suspension system to move more slowly when loads are removed from its corner of the car, but the unloading of the contact patch will be more abrupt. Softer rebound settings allow the suspension to move more quickly and the unloading of the contact patch happens more gradually
2. The suspension system must also reacts to track irregularlities - namely bumps. On a very smooth racetrack, you can get away with using stiffer bump and rebound settings, but remember that stiff settings slow down the suspension movement by having higher resistance to motion.
3. The downside of this maneuver is that if the suspension has to move fast to absorb a bump or series of bumps, it may not be able to react fast enough to keep the tires in contact with the road. Tires that spend half their time in the air don't provide much grip. Expect that the shock settings for bumpy racetracks will have to be softer in order to allow the suspension to move fast enough to keep the tires in contact with the track surface
4. Shock absorbers or more correctly Dampers, have the primary function of helping to control the energy stored up by the springs. A spring is a remarkable depository of energy. When the spring is compressed by a bump or a change in load on the spring, it stores the energy of the initial motion and feeds most of it back in the opposite direction. Without control, the spring would go through a number of cycles of compression and extending in response to its first deflection, losing a little energy with each cycle.
5. Ultimately, the shock setting doesn't determine how much load gets to the tyre or how much the suspension moves moves in response to the load. It alters the speed with which the load gets to the contact patch and the speed with which the suspension moves in response to the loads fed into it.
6. Expect that the shock settings for bumpy racetracks will have to be softer in order to allow the suspension to move fast enough to keep the tyres in contact with the track surface.

Congratulations you have simply condensed a large number of my quotes and references into a single place, its a handy list and one that I now hope you understand and acknowledge, as certain points on it you have previously disputed.

sucahyo
Try with less than 30mph. You don't feel any difference in handling for both? I do, d-low definitely better at grass.
reference 2, 3 and 6.

Yesterday I did the run again with 15/15 spring rate, bellow 30mph. d-high follow the grass bump better too. d-low has noticably lower wheel moement.

I will certainly try at speeds of less that 30mph, however this will not be until the end of the week as I will be away in Italy with work. Im sat at the airport typing this reply up onto word so I can upload it later. In regard to the results of the 15/15 spring rate test I would have to carry that one out (along with the below 30mph one) upon my return.

sucahyo
I am lost, what is the difference?
reference 1 and 4.

IMO, The car bouncing more because faster response time, less restricted spring and spreading load over longer period of time..

A big difference, you will notice that I quite clearly said that the car was jumping and that the suspension hardly moves. An important distinction, as 1 and 4 above discuss the movement of the suspension systems alone.

The cars reaction is a result of two things. The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered.

The second part of this is a limitation of the GT4 physics engine, which does not allow a car to roll or flip. The force of the impacts above are sufficient to flip or roll the car (not difficult given its low curb weight), however when the corner of the car that is being forced up reaches a certain point it is stopped. Its then forced back down and this continues until the car settles.

This is not the same as oscillations caused by over soft springs and dampers, which would have very visible oscillations of the suspension cycle.

This issue can be seen on occasion in real world racing when a stiff car hits a curb or rumble strip to quickly, off the top of my head I can cite the following examples.

British BTCC Gabrielle Tarqueine was almost infamous for this, rolling his Alfa on a number of occasions.
V8 Supercars IIRC it was a corner at Philips Island that a number of drivers had complained about that resulted in a number of cars rolling.
WRC Petter Solburg in the Rally of Germany last year (a tarmac rally that runs very stiff settings with low ride heights), the car came over a jump and hit a large rock. The resulting force was so great that the car was thrown into a series of end-over-end rolls.

All of the above are the result of cars hitting objects at speed and the suspension being unable to react quickly enough to control the car. Dont be mistaken into thinking that soft settings would have stopped all the above happening, but they would have lowered the level of force involved.

However GT4 is not the real world, and as such the limits on the cars rolling or flipping cause a bouncing effect on the whole car as it is forced up and down.

sucahyo
In other word, you say GT4 visual physics is flawed? Bug or design error (these two is different)?

Im saying that I will not trust one area of input over all the others, the reason why I picked the Caterham was that it allows the entire front suspension system to be shown. Which gives more visual information to work with; this additional information combined with feel, handling and noise is what I am using to base my tests on.

Ive lost count of the number of times I have said that I will not trust a single source of information in GT4, so yes I am saying that I do not 100% trust the tiny vibrations I see in the tyres, so I also look at the suspension, the feel, the handling and the noise.

Youre the one who has limited themselves by looking at a limited range of information and jumping to conclusions.

sucahyo
Why? Are you saying reference 3 is incorrect? I assume it means suspension move along with the tire.
Are you saying the wishbone movement is correct and tire movement isn't?
Try again with stiffer spring rate.

No I am not saying that point 3 is incorrect, in fact I have used that point (which I originally quote from Going Faster and you dismissed) to illustrate this before.

What I am saying is that a tyre will move if the suspension or the car moves, however the wishbones (being controlled by the springs and dampers) will only react if the suspension is able to react, they will also display the movement more clearly that the tyres/wheels alone.

As such they are a much more accurate (in GT4) indicator of the forces working on the car and its suspension system.

This does not in any way go against the point I have posted before or the Skip Barber quote. I will also try the higher spring rates upon my return from Italy.

sucahyo
I don't have that skill, I can't consistently brake at the same place. I guess I will see how B-Spec drive it next time.
My current assumption, If the car already dive when we realease the throttle, the car won't dive more when we hit the brake.

Sorry by you admit to not being able to drive consistent laps for testing yet expect us to accept the results of your tests? Come on, hitting a consistent braking point is not that damn hard, all it takes is to pick a spot and brake!!!

One of the first things you need to develop for testing set-up and tuning is the ability to drive consistent laps, until you can do that how can you compare one setting to another? Also until you can do that how can we consider any of your results to be accurate?

Also you assumption that no change in suspension loading will occur between releasing the throttle and full braking is another example of why you should not make assumptions. Quite simply its wrong; no ifs or buts; its just plain wrong.

Load transfer is dependent on the forces acting on the car, as you accelerate the load transfers to the rear and as you decelerate the load transfers to the front. The more you decelerate or accelerate the greater these forces, it can be simply and clearly demonstrated in a car on an empty road. Drive at a steady 30mph and take you foot of the throttle, only engine compression will be affecting the car and the load transfer will actually by quite small. Repeat and this time apply normal braking pressure and the load transfer will be increased, felt by the forces on your own body. Repeat and apply full braking force (an emergency stop in road terms, normally threshold braking for the track) and the increased forces on your car and body can be felt.

For what you are describing to happen (suspension reaching its limit of travel on just throttle lift), the spring rate would have to be barely sufficient to support the static un-sprung corner weight at each corner, which would also need to be severely under-damped. This would result in the suspension reaching its limit of travel upon the release of the throttle and the limited load transfer that would result from such an action.

The only other way I could imagine this happening if the suspension was removed and metal bars fitted instead, as this would result in zero suspension travel the difference between throttle lift and full braking would be nothing in regard to suspension travel.

However even in these totally ridiculous scenarios the limit of suspension travel (or absence of it), this would not stop the increase in load transfer as you moved from throttle lift to braking and full threshold braking.

This is one of the fundamental basics of the physics of racing, the greater the forces placed on a car (from accelerative forces of any kind, lateral or longitudinal) the greater the load transfer. This directly effects the distribution of this load, the reaction (and degree of reaction) from the suspension system and the ability of the tyres to grip.

If you are making assumptions as flawed as this one it is no surprise to me that you are having problems in other areas.

sucahyo
What I feel is different from yours. Why you keep saying visual is unreliable? I thought when you say your integra jump lower using d-low you believe GT4 visual is correct? If you say vibration is visual mistakes, direct jump after bump is also visual mistakes.

I have already covered this above, but feel that I need to re-enforce the point; as again we have some wonderful assumptions going on here. The Integra test (and I believe you should go back and read the whole damn thing) did not simply rely on one piece of information.

It was a test made up of all the elements I have discussed (visual, feel, handling, etc); you are the one who has been reliant on visual only input.

Additionally why does the fact that I dont 100% trust tiny amounts of tyre jitter make a big and visible jump a mistake? Thats one hell of a leap you are making.

Scaff
Everytime this thread 'pops' up again I run a new set of tests, over and over again and every single time it simply re-enforces that D-low is softer and D-high is firmer.

sucahyo

Same here.

Click to expand...

So are you saying you agree that D-low is softer and D-high is firmer?

sucahyo
I have my reason, I say that because noticing wheel vibration from 14" screen is definitely very hard for me. Curiously, using 15/15 spring rate make the vibration easier to see.

Well if you have youre reasons then say them? Although this part does again make things interesting, not only are you relying primarily on visual info, but visual info from a 14 TV that you admit makes things hard for you to see. Do you not see the problem here?

If you admit that you struggle to see what is happening (and again with the wheel/tyre look at the Caterhams wishbones) then why the hell should we trust your observations? For the record Im using a 32 Sony WEGA and its quite clear and easy to see the differences, maybe this is part of the issue.

sucahyo
And if I have different result?

Well lets look at this, if a number of us carry out a set test and all but one get the same result, then the chances are that the one with the differing results is either, not carrying out the test correctly or misinterpreting the results. It is possible that everyone else is wrong, but given the number of tests and the number of people who disagree with you (and the level of driving experience they have not just on the track but in the real world) it is unlikely that they are always wrong and you are the only person who is ever right.

Put simply you are the common denominator here, and either everyone else is wrong, your copy of GT4 is different to every other copy released or you are wrong. Now which one is the most likely?

Because to be blunt in this post you have said that you struggle to drive consistently, have trouble seeing the visual information that you are relying on and have a flawed understanding of the physics occurring. As I have said before, a lot of your reasoning and logic is flawed and you are very selective about the info you want to use, almost dismissing feel, handling and noise when it does not support what you want. Its an attitude that I find quite disturbing and at times quite ridiculous (such as when you dismissed Skip Barber out of hand as it did not fit youre view).

Now before you try and throw back the same accusation at me, read all of my posts on this subject (and others the GT4 & Brakes thread is a good example) very carefully. In my tests I take great care to include the widest range of information and feedback that I can, I carry out a range of tests to ensure that I can spot any mistakes I may make, I also run tests repeatedly to screen out any anomalies.

Take my tuning guides as an example, these were not just thrown together quickly, rather the result of testing from a period in excess of nine months with GT4 (from the day it was released in the UK). You will also see from my GT4 & Brakes tests that if I am unsure or have an issue with a test or result I am quite happy to say so. I have also on a number of occasions been quite happy to admit if I am wrong or have misunderstood something. Can you say the same?

Regards

Scaff

sucahyo · Apr 18, 2006

Scaff
In regard to the results of the 15/15 spring rate test I would have to carry that one out (along with the below 30mph one) upon my return.

Ok.

Scaff
A big difference, you will notice that I quite clearly said that the car was jumping and that the suspension hardly moves. An important distinction, as 1 and 4 above discuss the movement of the suspension systems alone.

Are you saying the car jump because the force from the tire directly to the car body (bypassing suspension) :confused:

? How is that possible? Oh wait, tyre have spring rate too, but I don't believe GT simulate this.

Scaff
The cars reaction is a result of two things. The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered.

Are you saying that if we drop a car from 1 meter height with very stiff suspension it will bounce back at almost 1 meter if the damper stiff enough? where do the jumping power come from ?
Weird, are you sure you not mistype this ? Are you getting this conclusion from false damping knowledge in GT4? Do skip barber have some part explaining about this?

From what understand in real life and in GT (if we assume 10 is softest), when we drop the car from 1 meter height soft damper will jump again higher than stiff damper. A very soft damper will make the car jump back to close at 1 meter if the spring is strong enough. A very stiff damper will reduce the kinetic power completely that the car will not jump.
What make the car jump is spring rate, if we use soft damper the spring rate will work efeciently and return the power more resulting in higher jump. If we use stiffer damper the spring rate will return the power less resulting in lower jump because the damper will absorb the power more.
Brick (Car body) do not have jumping power. Fitting damper in a pogo stick will reduce its jumping capability. I am sure this is only a mistype. If it doesn't, what can I say, we have different understanding or real life physics too

.

Scaff
The second part of this is a limitation of the GT4 physics engine, which does not allow a car to roll or flip. The force of the impacts above are sufficient to flip or roll the car (not difficult given its low curb weight), however when the corner of the car that is being forced up reaches a certain point it is stopped. It's then forced back down and this continues until the car settles.

I don't agree with force back down. Are you saying the car bounce back after hitting virtual roof?
What I know about this roll and pitch limit is when the car roll or pitch exceed allowable limit, it will STOP progressing. It will not bounce it back. If you hit the wall where your car supposed to be flip up and spin it will fly spinning left or right but will not bouncing up and down, the car pitch or roll never exceed the limit.

Scaff
This issue can be seen on occasion in real world racing when a stiff car hits a curb or rumble strip to quickly, off the top of my head I can cite the following examples.

I agree that car can't roll over in GT4.

Scaff
All of the above are the result of cars hitting objects at speed and the suspension being unable to react quickly enough to control the car. Don't be mistaken into thinking that soft settings would have stopped all the above happening, but they would have lowered the level of force involved.

But I still not clear of what make car jumping caused by body and caused by suspension different, both is reaction from tire meeting to the road.

Scaff
However GT4 is not the real world, and as such the limits on the cars rolling or flipping cause a bouncing effect on the whole car as it is forced up and down.

I don't agree, GT only prevent the roll or pitch from exceeding the limit, it does not cause bounce, it does not limit car elevation.

Scaff
What I am saying is that a tyre will move if the suspension or the car moves, however the wishbones (being controlled by the springs and dampers) will only react if the suspension is able to react, they will also display the movement more clearly that the tyres/wheels alone.

What happen if the suspension is unable to react?
From what I know, suspension movement is slower than the tire.

Scaff
Sorry by you admit to not being able to drive consistent laps for testing yet expect us to accept the results of your tests? Come on, hitting a consistent braking point is not that damn hard, all it takes is to pick a spot and brake!!!

Noticing feel on heavy car is easy, but I am unable to feel handling difference in Caterham on tarmac, even with 15/15 spring rate. I try braking test on my next chance.

Scaff
One of the first things you need to develop for testing set-up and tuning is the ability to drive consistent laps, until you can do that how can you compare one setting to another? Also until you can do that how can we consider any of your results to be accurate?

Even if I can't do my lap consistently, I still can tune. For acceleration I can use drag strip, for grip I have to drive it my self. Even with my bad driving skill, there are people that praising my tuning skill.
I don't want to enter lion's mouth by challenging you to GT4 tuning duel

.

Scaff
Also you assumption that no change in suspension loading will occur between releasing the throttle and full braking is another example of why you should not make assumptions. Quite simply its wrong; no ifs or buts; its just plain wrong.

What I mean is suspension is already move when the throttle is released so when you hit the brake the suspension move less on softer damper.

Scaff
Additionally why does the fact that I don't 100% trust tiny amounts of tyre jitter make a big and visible jump a mistake? That's one hell of a leap you are making.

I don't ignore it. And when I put all this small bit together it all make sense. From your view of damper there always small bits like this that doesn't fit.

Scaff
So are you saying you agree that D-low is softer and D-high is firmer?

No, I mean I do the test over and over again and the result is the same, damper 10 is softest.

Scaff
If you admit that you struggle to see what is happening (and again with the wheel/tyre - look at the Caterham's wishbones) then why the hell should we trust your observations? For the record I'm using a 32" Sony WEGA and it's quite clear and easy to see the differences, maybe this is part of the issue.

Nice set

, I use 21" set, PAL. I don't notice the tire jiggle at first, only notice it on 3rd run. I figure if I have problem noticing this on 21" screen, anyone with 14" set would have more problem noticing it.

Scaff
Take my tuning guides as an example, these were not just thrown together quickly, rather the result of testing from a period in excess of nine months with GT4 (from the day it was released in the UK). You will also see from my GT4 & Brakes tests that if I am unsure or have an issue with a test or result I am quite happy to say so. I have also on a number of occasions been quite happy to admit if I am wrong or have misunderstood something. Can you say the same?

If you see my gt.cellphonespec.com, that is what I do. Not as extensive as yours, but I don't forbid hacked or irregular tuning. About damper I still believe that I am right.

And I really want you to explain about this statement:
'The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered."

As this is a real life knowledge, it is very important to me to know your view.

Dave_George · Apr 18, 2006

sucahyo
Ok.

Are you saying the car jump because the force from the tire directly to the car body (bypassing suspension) ? How is that possible? Oh wait, tyre have spring rate too, but I don't believe GT simulate this.

My understanding of this is that if the damping were too stong, the forces would transfer through to the car body and cause it to jump, as Scaff mentioned the touring cars when set very stiff will leave the ground when a bump is encountered at speed. The forces are not bypassing the suspension, it just cant react quick enough.

sucahyo
Are you saying that if we drop a car from 1 meter height with very stiff suspension it will bounce back at almost 1 meter if the damper stiff enough? where do the jumping power come from ?
Weird, are you sure you not mistype this ? Are you getting this conclusion from false damping knowledge in GT4? Do skip barber have some part explaining about this?

I cant understand why you mention dropping a car from 1 metre? The example given of cars hitting kerbs and leaving the track when too stiff seems very logical to me and if you watch motor racing on TV then you will more than likely see it happen for yourself!

sucahyo
From what understand in real life and in GT (if we assume 10 is softest)

10 isnt the softest, 10 is the hardest setting you can set a damper too in GT4, this has been covered already.

Regarding the point Scaff made about you admitting you are unable to complete consistent clean laps when testing, I have to wholeheartedly agree with Scaff that I couldnt trust your judgement in tuning if you cannot drive consistently. If you are leaving the track a lot and driving over the grass then maybe you need to address how you drive first, and then turn your attention to tuning. I will be the first to admit my driving style used to be poor with too much late braking and understeer on most corners (resulting in leaving the track a lot), as a result I used to try to tune out all of the understeer - In some cases it was my driving style causing the problems - not the car, as a result of that my tuning then introduced other problems.

Suffice to say I approach things differently now.

regards

David

Mt. Lynx · Apr 18, 2006

sucahyo
Are you saying the car jump because the force from the tire directly to the car body (bypassing suspension) ? How is that possible? Oh wait, tyre have spring rate too, but I don't believe GT simulate this.

Actually it does. And I have also found another reason NOT to trust the visual information too much (read: not at all). I watched a replay of the FGT around El Capitan, and noticed something wierd; the wishbones did not move at all! All suspensiontravel was visually simulated by tyres alone! This is a serious flaw, and I will never ever trust what I see in GT4 again! As I´ve said before, feel is a far better way to tune, and if things in GT4 are not visually accurate, but feels correct, then feel is way to go.

sucahyo
Are you saying that if we drop a car from 1 meter height with very stiff suspension it will bounce back at almost 1 meter if the damper stiff enough? where do the jumping power come from ?
Weird, are you sure you not mistype this ? Are you getting this conclusion from false damping knowledge in GT4? Do skip barber have some part explaining about this?

No, that is not what he said at all. He said that a too stiff car will have a more violent reaction to a bump than a soft car.
The cars weight would make it impossible for it to jump back to the same height. AFAIK, no spring can do that. And also AFAIK this does not occur in GT4.

sucahyo
From what understand in real life and in GT (if we assume 10 is softest), when we drop the car from 1 meter height soft damper will jump again higher than stiff damper. A very soft damper will make the car jump back to close at 1 meter if the spring is strong enough. A very stiff damper will reduce the kinetic power completely that the car will not jump.

Right, but that is not how a car encounters surface. A too hard damper in this case, would destroy the car, and possibly bend the chassis. Think of it this way: take an ordinary dinnerplate, drop on the floor, and it will break. Now place a pillow underneath, and it won´t break, but it will occilate somewhat on the pillow. But if the pillow is too soft, the plate will fall through and break anyway.

sucahyo
What make the car jump is spring rate, if we use soft damper the spring rate will work efeciently and return the power more resulting in higher jump. If we use stiffer damper the spring rate will return the power less resulting in lower jump because the damper will absorb the power more.
Brick (Car body) do not have jumping power. Fitting damper in a pogo stick will reduce its jumping capability. I am sure this is only a mistype. If it doesn't, what can I say, we have different understanding or real life physics too .

Fitting a damper in a pogostick, actually would increase its jumping power to a certain degree, and if I´m not mistaken, a pogostick has a damper.
I have seriously started to belive that you don´t actually know what a damper does, and thus jumping to false conclusions; this above confirms that.

I´ve said this before, think in the terms of pressure inside the dampers. the more pressure, the stiffer it gets, and the stiffer it is, the more force it applies on the springs, and as a result the surface that you drive on gets more transfer directly to the chassis itself, rather than absorbing it. This may cause jumping and erratic behaviour if the forces encountered (bumps, kerbs, speed) are large enough. This may be true to softer damping too, but the forces needed has to be greater.
However, a too soft setting may cause the car to bottom out, and that in turn may cause the car to jump when the chassis hit the surface directly. All this is dependant on how hard the springs are, and how large the workload is.
I recommend you to test this on the Hunauderies straight at Le Mans (La Sarthe II) in a group C car (recommend Nissan R92CP) as soon as you can.
Follow these steps:
Set rideheight to 90, a good height for this track, leave the rest.
1. Max springs, d-high
2. Max springs, d-low
3. Lowest springs, d-high
4. Lowest springs, d-low

1 will be virtually impossible to drive, since you will jump around badly.
2 will be slightly better, but very vibrating
3 will be pretty good, but jumpy
4 will possibly bottom out and cause jump, but overall this will be the best.

sucahyo
I don't agree, GT only prevent the roll or pitch from exceeding the limit, it does not cause bounce, it does not limit car elevation.

but the limitations do not make the suspension stop working, does it? So when a car hits such a limit, it may cause strange and unpredictable suspensionbehaviour.

sucahyo
And I really want you to explain about this statement:
'The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered."

This is exactly what I was talking about above.

sucahyo · Apr 19, 2006

To explain why I mention dropping car from 1 meter height:

sucahyo
I drive with d-high first. Since I am not so good in driving, I drive trough the grass often. When the car passing the side rumble strip to go back to the road the car become very lively. It bounce around few time before it stop.

Next is d-low. This time I notice that the car bounce a lot less on the road, . On replay I see some suspension movement.

Curious with less bouncing using d-low, I try again with d-high. And I notice that in grass d-high would bouncing less, where in tarmac d-high would bouncing more.

sucahyo
- for bouncing after go back to the road, I only see it happen from rear view, d-high bouncing periode is longer than d-low, I can't describe the feel.

Scaff
In regard to the 'car' bouncing more on return to tarmac then yes D high settings do cause the 'car' to jump more. Now look at the actual suspension itself, it hardly moves, the 'car' jumping is a result of the force being dirrectly transferred through the suspension and onto the cars chassis.

sucahyo
I am lost, what is the difference?
reference 1 and 4.

IMO, The car bouncing more because faster response time, less restricted spring and spreading load over longer period of time..
A big difference, you will notice that I quite clearly said that the car was jumping and that the suspension hardly moves. An important distinction, as 1 and 4 above discuss the movement of the suspension systems alone.

Scaff
The cars reaction is a result of two things. The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered.

So, what I want to confirm is how come rejump happen in longer periode of time when using d-high if its not softest. So not how much it's jump after meeting bump.

This is very serious matter for me. Scaff please ask any expert people around you. If you receive an embarasing reply or treatment, I don't mind if you ban me for a week. Since what you say about stiffer damper make car re jump more does not make any sense for me.

It contradict with this too: "Shock absorbers or more correctly Dampers, have the primary function of helping to control the energy stored up by the springs. A spring is a remarkable depository of energy. When the spring is compressed by a bump or a change in load on the spring, it stores the energy of the initial motion and feeds most of it back in the opposite direction.".

My translation for this for car dropping from 1 meter height is: damper reduce the energy transfered by or to springs.
With softer damper it will force the car body to the opposite direction, up, easier. With no damper it will make the car jump closer to 1 meter. With stiffer damper it will make the car jump lower. With very stiff damper it will make the car not jump by reducing the energy completely. With ultra stiff damper (or replacing it with swaybar) it smash the ground with little or no suspension movement (if the suspension do not break first).

If Scaff confirm that the previous statement is a mistype, I will NOT assume that Scaff agree 10 is softest. But Scaff still have to explain the caterham rebouncing behaviour.

Dave_George
My understanding of this is that if the damping were too strong, the forces would transfer through to the car body and cause it to jump, as Scaff mentioned the touring cars when set very stiff will leave the ground when a bump is encountered at speed. The forces are not bypassing the suspension, it just cant react quick enough.

If the force transfered to the body, it will break the body, not make it bounce up again. It's the spring that make it jump. It stored the energy when compressed by the fall, and after the fall stop, the spring release the energy by pushing the car up. It's damper job to reduce the energy that the spring captured (bound) and released (rebound). (do I use energy term correctly?)
Too quick so that it bypassing the suspension, how fast is that? Are you saying that if we drop the car from 1km height the car will be broken but the suspension doesn't?

It's the suspension that have to face the force, I don't think it can be bypassed. or react not quick enough. I really can't imagine it.

Dave_George
I cant understand why you mention dropping a car from 1 metre? The example given of cars hitting kerbs and leaving the track when too stiff seems very logical to me and if you watch motor racing on TV then you will more than likely see it happen for yourself!

I need explanation for what happen after the caterham jump back to the tarmac. Why d-low have bounce count less.

Dave_George
10 isnt the softest, 10 is the hardest setting you can set a damper too in GT4, this has been covered already.

No, there is too much inconsistency.

Dave_George
Regarding the point Scaff made about you admitting you are unable to complete consistent clean laps when testing, I have to wholeheartedly agree with Scaff that I couldnt trust your judgement in tuning if you cannot drive consistently. If you are leaving the track a lot and driving over the grass then maybe you need to address how you drive first, and then turn your attention to tuning.

Up until now, my total GT4 playing hour is less than 24 hour. I use 3/4 of that time to do 300mph max speed test. Now, I can drive better in GT4 because I already found a code to make GT2 drive more like GT4.

Dave_George
I will be the first to admit my driving style used to be poor with too much late braking and understeer on most corners (resulting in leaving the track a lot), as a result I used to try to tune out all of the understeer - In some cases it was my driving style causing the problems - not the car, as a result of that my tuning then introduced other problems.
Suffice to say I approach things differently now.

Agree, experience count.

Team666
Actually it does. And I have also found another reason NOT to trust the visual information too much (read: not at all). I watched a replay of the FGT around El Capitan, and noticed something wierd; the wishbones did not move at all! All suspensiontravel was visually simulated by tyres alone! This is a serious flaw, and I will never ever trust what I see in GT4 again! As I´ve said before, feel is a far better way to tune, and if things in GT4 are not visually accurate, but feels correct, then feel is way to go.

I see, then Scaff advise to look at the suspension is wrong. So, based on that looking the wheel/tire is more correct.

Team666
No, that is not what he said at all. He said that a too stiff car will have a more violent reaction to a bump than a soft car.
The cars weight would make it impossible for it to jump back to the same height. AFAIK, no spring can do that. And also AFAIK this does not occur in GT4.

See above. I need explanation why d-low show stiffer damper behaviour on car landing bounce. I assume Scaff trying to explain this.

Team666
Right, but that is not how a car encounters surface. A too hard damper in this case, would destroy the car, and possibly bend the chassis. Think of it this way: take an ordinary dinnerplate, drop on the floor, and it will break. Now place a pillow underneath, and it won´t break, but it will occilate somewhat on the pillow. But if the pillow is too soft, the plate will fall through and break anyway.

The pillow is spring, right? And I think dropping from 1 meter can be happen in Paris dakkar.

Team666
Fitting a damper in a pogostick, actually would increase its jumping power to a certain degree, and if I´m not mistaken, a pogostick has a damper.
I have seriously started to belive that you don´t actually know what a damper does, and thus jumping to false conclusions; this above confirms that.

Do you remember that the stiffer the damper, the harder it work to stop suspension movement? How can oil that have to be force to pass small hole inside damper can help increase jumping ability?
Even the Skip barber mention this: "A stiffer bump setting slows down the motion on its corner ans speeds up the load transfer. A softer bump setting does the opposite - it allows the suspension to move faster and spreads the changes in loading out over a longer period of time."
I don't dismiss this, how about you?

Scaff, what do you say about this? because of your mistype, everyone start to think that that is what happen in real world.

Team666
I´ve said this before, think in the terms of pressure inside the dampers. the more pressure, the stiffer it gets, and the stiffer it is, the more force it applies on the springs, and as a result the surface that you drive on gets more transfer directly to the chassis itself, rather than absorbing it. This may cause jumping and erratic behaviour if the forces encountered (bumps, kerbs, speed) are large enough. This may be true to softer damping too, but the forces needed has to be greater.

stiffer damper will absorb the force more, not increase it.

Team666
However, a too soft setting may cause the car to bottom out, and that in turn may cause the car to jump when the chassis hit the surface directly. All this is dependant on how hard the springs are, and how large the workload is.
I recommend you to test this on the Hunauderies straight at Le Mans (La Sarthe II) in a group C car (recommend Nissan R92CP) as soon as you can.

Ok, I do this too on my next chance.

Team666
Follow these steps:
Set rideheight to 90, a good height for this track, leave the rest.
1. Max springs, d-high
2. Max springs, d-low
3. Lowest springs, d-high
4. Lowest springs, d-low

1 will be virtually impossible to drive, since you will jump around badly.
2 will be slightly better, but very vibrating
3 will be pretty good, but jumpy
4 will possibly bottom out and cause jump, but overall this will be the best.

I am sure I will get the same result, although we have different opinion of what causing it.

Team666
but the limitations do not make the suspension stop working, does it? So when a car hits such a limit, it may cause strange and unpredictable suspensionbehaviour.

Yes, what I mean is it stop the car from rolling or pitching further. But I recall the pitch or roll angle is pretty high, maybe 60 degree or more. So this will rarely disturb driving. I don't encounter it when I drive the caterham.

Scaff · Apr 19, 2006

Please be aware that this post was written off-line as I am working in Italy this week and my hotel does not have internet access, as such I have no access to my normal sources of information and this post is principal written off the top of my head. Also a very strong possibility exists that this post may have been written under the influence of a combination of beer, wine and grappa.

Sucahyo
Are you saying the car jump because the force from the tire directly to the car body (bypassing suspension)? How is that possible? Oh wait, tyre have spring rate too, but I don't believe GT simulate this.

Sucahyo
Are you saying that if we drop a car from 1 meter height with very stiff suspension it will bounce back at almost 1 meter if the damper stiff enough? where do the jumping power come from ?
Weird, are you sure you not mistype this ? Are you getting this conclusion from false damping knowledge in GT4? Do skip barber have some part explaining about this?

From what understand in real life and in GT (if we assume 10 is softest), when we drop the car from 1 meter height soft damper will jump again higher than stiff damper. A very soft damper will make the car jump back to close at 1 meter if the spring is strong enough. A very stiff damper will reduce the kinetic power completely that the car will not jump.
What make the car jump is spring rate, if we use soft damper the spring rate will work efeciently and return the power more resulting in higher jump. If we use stiffer damper the spring rate will return the power less resulting in lower jump because the damper will absorb the power more.
Brick (Car body) do not have jumping power. Fitting damper in a pogo stick will reduce its jumping capability. I am sure this is only a mistype. If it doesn't, what can I say, we have different understanding or real life physics too.

Sucahyo
What happen if the suspension is unable to react?
From what I know, suspension movement is slower than the tire.

Im going to cover these three together as they are directly related.

I dont understand how you can say that you understand how the suspension system of a car works, yet you appear to have little understanding of the forces at work here.

If a car hits a bump and the suspension cant react quickly enough (as it is too stiff) then the force of the of the impact has to go somewhere, it cant just disappear. It is transferred through the suspension directly to the car itself.

I have covered this before, if a car was fitted with a suspension system made from metal bars, when it hit a bump then a small amount of the force of the impact would be absorbed by the metal bars, but the majority of the force would be transferred through to the car itself. The force is not bypassing the suspension, its being transferred. The same thing occurs if a car is stiffly sprung and damped, the suspension cant react quickly enough to move the tyre over the bump and control the majority of the force, so it is transferred to the car.

Now all suspension settings (that are driveable) will transfer some of the force to the car, this is what we feel in the car when you drive over a bump. Softer settings control this more and feel smoother, stiffer settings control this less well and feel harsher.

In regard to youre car being dropped from a height, I did not say anything like that at all and as others have said, what does this example have to do with driving over bumps? Nothing at all, so why mention it? As Team666 has said this is not the same a encountering a bump, dropping a road car from any significant height would actually snap the suspension mounting points, as the force was transferred through the suspension (almost certainly unable to cope road cars are not designed to be dropped). Which again proves the point I am making.

You also say that a car does not have jumping power itself, and as a basic (but strangely worded) statement that is true. However a cars basic structure is by no means rigid, in fact it is flexible, and as any flexible material it will store and release energy.

For information on this I will point you to a series of very complex and detailed articles called The Physics of Racing, which is a highly regarded (but very technical) look at how physics and racing interact. They were written by a physics PhD and racer called Brian Beckman and have been peer reviewed by physicists and racers alike.

This extract discusses what would happen if a car with no suspension hits a bump, and quite clearly states that it would launch from the top of the bump, it then (again quite clearly) states that tyres and suspension would endeavour to keep the car on the ground.

The Physics of Racing Bumps
As to the trailing edge, a simplistic car-as-rigid-body would just launch ballistically from the top of the bump. Of course, in a real car, tyre elasticity and the suspension would endeavour to keep the tyres on the ground. Short of launching, there would just be weight loss causing rebound of the tyre sidewalls and the suspension springs. Nevertheless, everyone knows that a ballistic projectile assumes a parabolic flight path, so, as long as the parabola off the top of the bump remains vertically above the down-ramp, our car-as-rigid-body is assured of taking to the air. With the simple bump geometry, we can see that a parabolic launch always starts off above the trailing-edge triangle. It intersects the road again either somewhere on the down-ramp or on the following flat bit of road, depending on horizontal speed.

Here is a direct link to the full section on bumps

http://www.miata.net/sport/Physics/15-Bumps-In-The-Road.html

So my statement that if force is transferred through the suspension (as it is too rigid to react to the impact) to the car will make it jump is not only correct, but stands up to detailed physics!

Now onto your point about how dampers work in this, I have to agree with Team666 that again you seem to be misunderstanding what a damper does. You say that

Sucahyo
What make the car jump is spring rate, if we use soft damper the spring rate will work efeciently and return the power more resulting in higher jump. If we use stiffer damper the spring rate will return the power less resulting in lower jump because the damper will absorb the power more.

.

Now the spring rate does two things, first it supports the un-sprung weight of the car; secondly it determines how much movement will occur under load transfer. This will then determine how the load is distributed at a given end of the car.

Dampers do not support any load at all, nor do they directly determine how much movement occurs under load transfer*. They determine how quickly the suspension will react to the load transfer, softer damper settings allowing quicker reactions and stiffer damper settings resulting in slower reactions.
However if a damper is set to stiffly for the spring rate then it will actually stop the spring from being able to react as quickly as it needs to and the force from the bump will be transferred through the suspension (which was not able to react quickly enough) and onto the car itself. The car will react as described above and if the force of impact with the bump is great enough then that corner/side of the car will loose contact with the ground.

*Stiff dampers can give the impression of determining the amount of movement a suspension system will travel through, however this is because if the springs are over-damped they will limit the springs ability to react. The effect is similar to increasing the spring rate itself. However in the real world dampers are force sensitive, and react differently to low and high speed impacts, as such the effect they have over the springs varies. So the amount of suspension travel is still determined directly by the spring rate, but indirectly affected by the damper rate.

Sucahyo
I don't agree with force back down. Are you saying the car bounce back after hitting virtual roof?
What I know about this roll and pitch limit is when the car roll or pitch exceed allowable limit, it will STOP progressing. It will not bounce it back. If you hit the wall where your car supposed to be flip up and spin it will fly spinning left or right but will not bouncing up and down, the car pitch or roll never exceed the limit.

Sorry but I cant agree with some of this.

If a car in GT4 leaves the ground in a flat spin, then the system will allow it to gain altitude, however it does not reach a certain altitude and then stop. If you are saying that nothing will force it back down then why does the car return to the ground?

To say that it just stops progressing is too state that the car will not return to the ground? It makes no sense.

However it is quite clear that this is not what I have been discussing at all, I have consistently been talking about a situation where a car has one corner or side being forced up and the physics engine stopping it when a certain angle (in relation to the opposite side/corner) is reached, and again the car does not just stop at this point but returns to the ground.

Now I think that its quite clear to say that this does not happen in the real world, the car may exceed an angle that would cause it to roll or flip, GT4 stops this happening. As such the reaction of a car in this situation can not be directly compared to the real world. The effect as I (and it appear most other people) see it is that it causes the car to bounce or jump from one side/corner to the other. This is GT4 coping with a situation from an over-stiff car that should (in the real world) have flipped or rolled, but in GT4 is not allowed to.

Sucahyo
But I still not clear of what make car jumping caused by body and caused by suspension different, both is reaction from tire meeting to the road.

It may not be clear to you (and I honestly do not know why) but it seems to be to everyone else.

The Integra test has a direct and clear real world link, which is covered by all the Skip Barber info I have provided and the Physics of Racing piece on bumps. If two cars (one with softer damping and one with firmer damping) encounter the same bump at the same speed, then the one with softer damping will be better able to manage the bump than the firmer one. The firmer damped car is the more likely of the two (all other things being equal) to loose contact with the ground.

Therefore logic will dictate that in GT4 the car that leaves the ground in the Integra test will most likely be the one with the firmer damper settings. As the car with the higher damper values lost contact with the track surface when it encountered the curb, it is logical to conclude that higher damper values in GT4 are firmer.

When you then include the indicators from feel, handling and noise with the above visual information (and the other tests) it is both logical and more probable that higher damper values in GT4 are firmer.

Sucahyo
I don't agree, GT only prevent the roll or pitch from exceeding the limit, it does not cause bounce, it does not limit car elevation.

I have covered this in great detail above.

Sucahyo
Noticing feel on heavy car is easy, but I am unable to feel handling difference in Caterham on tarmac, even with 15/15 spring rate. I try braking test on my next chance.

You are not able to feel handling differences on the Caterham on tarmac using settings this extreme? Im sorry but that is quite worrying, the difference in feel and handling of the car between 1/1 and 10/10 is very, very clear. Its like driving two different cars.

How do you tune by feel if you cant feel differences this great?

Sucahyo
Even if I can't do my lap consistently, I still can tune. For acceleration I can use drag strip, for grip I have to drive it my self. Even with my bad driving skill, there are people that praising my tuning skill.
I don't want to enter lion's mouth by challenging you to GT4 tuning duel.

I did not say you could not tune, I said that not being able to drive consistent laps makes it hard to compare different set-ups and changes. This you have confirmed above when you say that you cant feel the difference between settings for the Caterham.

People may well praise your tuning skill, but having read many of your threads and posts in the GT2 forum and here, a number of people also disagree with your set-ups. This is quite normal with setups and tuning. I have always said that set-ups are a very personal thing and a set-up that is great for driver A, will not work for driver B. As such tuning duels are an almost pointless exercise.

However youre tuning is not at question here, your understanding of dampers and the values used in GT4 is what is at question.

Sucahyo
What I mean is suspension is already move when the throttle is released so when you hit the brake the suspension move less on softer damper.

Thats quite different to what you originally said, which was

Sucahyo
My current assumption, If the car already dive when we realease the throttle, the car won't dive more when we hit the brake.

Please think more carefully about what you are posting as you are being very inconsistent.

Also as has already been said, the amount (in length of suspension travel) is not principally determined by the damper rate. As long as the damper rates are not so firm as to limit the springs ability to react then when the throttle is released (all other things being equal) the load transfer would be the same. Therefore the amount of movement would not be affected by the damper; the damper would determine how quickly this movement occurred, but not how much movement will occur.

Sucahyo
I don't ignore it. And when I put all this small bit together it all make sense. From your view of damper there always small bits like this that doesn't fit.

Sucahyo
No, I mean I do the test over and over again and the result is the same, damper 10 is softest.

Im sorry but I do not see how you can say that when you put everything together it all points to high damper values being soft.

How then do you explain the Integra test, the difference in feel and handling, the significant change in feel and the clear difference in suspension reactions in the Caterham tests? None of these fit your view of things, instead you devise very convoluted and overly complex theories (that do not match the real world in many cases) to prove your point.

Every logical test and comparison to the real world point to GT4 damper settings being higher = firmer and lower = softer.

Sucahyo
Nice set , I use 21" set, PAL. I don't notice the tire jiggle at first, only notice it on 3rd run. I figure if I have problem noticing this on 21" screen, anyone with 14" set would have more problem noticing it.

First its a 14 set, now its a 21 set, which is it?

Sucahyo
Yes, I am not saying that 0/0 camber is incorrect for stock car (I even open old hayes book to check before posting that) , but I am saying using 2.0/1.0 for default value for FC suspension (1/0.5 sport?) is irresponsible. How come they use smaller camber for softer suspension is what I curious about. Do they programmed camber to be reversed too? (it cross my mind too, but camber seems ok).

Why is picking a value to use as a base value irresponsible? I fail to understand this; its a default value that as far as I can see you are the only person I have ever come across who has a problem with it. I also do not understand why you have such an issue with it; you can adjust it on the various suspension types. Again you have changed youre comments on this, first you have an issue with the stock suspension settings and now you have no issue with them, so once again youre being inconsistent.

Sucahyo
If you see my gt.cellphonespec.com, that is what I do. Not as extensive as yours, but I don't forbid hacked or irregular tuning. About damper I still believe that I am right.

Yes I understand that you still believe you are right, however you did not answer my question regarding everyone elses thoughts, particularly this question.

Scaff
Put simply you are the common denominator here, and either everyone else is wrong, your copy of GT4 is different to every other copy released or you are wrong. Now which one is the most likely?

As I say, you may believe you are right, but very few other people agree, now either (as I asked above and before) everyone else is wrong, your copy of GT4 is different to every other copy released or you are wrong. So which one do you believe?

Sucahyo
And I really want you to explain about this statement:
'The first is what happens when a very stiff car (from the restricting effect of the high damper settings) hit a bump, as the suspension is unable to react quickly enough to handle the impact; the resulting force is transferred directly to the car. This causes the whole car to jump on the corner where the bump was encountered."

As this is a real life knowledge, it is very important to me to know your view.

This I have answered in great detail above.

Regards

Scaff

sucahyo · Apr 19, 2006

Scaff
If a car hits a bump and the suspension can’t react quickly enough (as it is too stiff) then the force of the of the impact has to go somewhere, it can’t just disappear. It is transferred through the suspension directly to the car itself.

Let me explain it step by step. You talking like it all happen at once.

My explanation
The car at 1 meter height
- suspension is lower than zero posistion from tire weight

The car hit the ground, pushed down by car weight
- spring compressed, and fight back, force the car to go up
- the amount of energy absorbed by spring is reduced by damper (bound), stiffer damper reduce the energy absorbed by spring more.

The car reach the lowest position
- spring start to expand

the car pushed up by the spring
- damper (rebound) reduce the energy released by spring

if the energy not reduced by damper much the car able to leave the ground again
If the energy absorbed by damper much the car movement can stop at lowest posistion if damper is very stiff or bounce up a little if the damper is not too stiff.

Your explanation
The car at 1 meter height
- suspension is lower than zero posistion from tire weight

The car hit the ground, pushed down by car weight
- if damper is stiff (10) the suspension not reacting fast enough and it send the force directly to the car body
- if the damper value is bellow that, the reaction is unknown
- car body stored the energy?

The car reach the lowest position
- car body start to straighten up?

the car go up
- if the car body is very elastic it can leave the ground again?
- if the car body is not very elastic it do not leave the ground?

It sound like cartoon movie ..............

Scaff
I have covered this before, if a car was fitted with a suspension system made from metal bars, when it hit a bump then a small amount of the force of the impact would be absorbed by the metal bars, but the majority of the force would be transferred through to the car itself. The force is not bypassing the suspension, it’s being transferred. The same thing occurs if a car is stiffly sprung and damped, the suspension can’t react quickly enough to move the tyre over the bump and control the majority of the force, so it is transferred to the car.

From what I know, if the force transfered to the car, it will do some damage to the car. If the car is strong, it will do some damage to the road. If both are strong I don't know. But metal car do not store energy as good as spring. And it can't make the car to jump back to the air again !

Scaff
Now all suspension settings (that are driveable) will transfer some of the force to the car, this is what we feel in the car when you drive over a bump. Softer settings control this more and feel smoother, stiffer settings control this less well and feel harsher.

Yes.

Scaff
In regard to you’re car being dropped from a height, I did not say anything like that at all and as others have said, what does this example have to do with driving over bumps? Nothing at all, so why mention it? As Team666 has said this is not the same a encountering a bump, dropping a road car from any significant height would actually snap the suspension mounting points, as the force was transferred through the suspension (almost certainly unable to cope – road cars are not designed to be dropped). Which again proves the point I am making.

I need an explanation to caterham jump and jump and jump again this time. Why it is happen more on d-high.
If you see car chasing movie with many hilly road jump (in San Fransisco?) we can frequently see car jumping more than 1 meter. In rally word 1 meter is a bit high, but I am very sure that even normal passenger car rarely snap its suspension if its landing on its all 4 tire at once. But even landing from height with 2 tire still don't snap the suspension (Fast & Furious 2).

Scaff
You also say that a car does not have ‘jumping power’ itself, and as a basic (but strangely worded) statement that is true. However a car’s basic structure is by no means rigid, in fact it is flexible, and as any flexible material it will store and release energy.

I am sure the car joint will break first before it can fight back. A direct frontal hit do not make the car bounce back if the speed is high enough doesn't it? Are you saying you never hit a fence or wall before? Maybe you should try it and see how much the car bounce back. I am sure it will bounce back if you hit it at 5 mph. but hitting those at 30mph will surely break something.
I forget the formula for calculting speed from drop. But it's not important, there is no way car body alone can make the car doing re jump again.

Scaff
For information on this I will point you to a series of very complex and detailed articles called ‘The Physics of Racing’, which is a highly regarded (but very technical) look at how physics and racing interact. They were written by a physics PhD and racer called Brian Beckman and have been peer reviewed by physicists and racers alike.

This extract discusses what would happen if a car with no suspension hits a bump, and quite clearly states that it would launch from the top of the bump, it then (again quite clearly) states that tyres and suspension would endeavour to keep the car on the ground.

Here is a direct link to the full section on bumps

http://www.miata.net/sport/Physics/15-Bumps-In-The-Road.html

So my statement that if force is transferred through the suspension (as it is too rigid to react to the impact) to the car will make it jump is not only correct, but stands up to detailed physics!

That is a good link. But there is no where in those link explaining that when the force will go to the car it will make it jump. It assume the car body is full rigid body to simplify calculation. It does not explain car elasticity like you mention.

http://www.miata.net/sport/Physics/15-Bumps-In-The-Road.html
If we assume a simplistic model of the car as a rigid body, we get an instantaneous, infinite acceleration right at the instant the car contacts the rising edge. We get further infinite, vertical accelerations at the two other cusps of bump the geometry. However, we know that the tyres and suspension will smooth out these sudden impulses.

I don't dismiss this link. It just that this link doesn't explain your statement.
I can use this link to explain that spring and damper work together to smooth out the sudden impulses.

I think I will wait until you get back, maybe you can show more direct explanation. And if you can't find this in skip barber book, it is either:
- you miss it
- skip barber do not cover it
- it does not happen in real life

I choose third option, car dropping from height can be pushed back to the air with car body elasticity does not happen in real life

Scaff
Dampers do not support any load at all, nor do they directly determine how much movement occurs under load transfer*. They determine how quickly the suspension will react to the load transfer, softer damper settings allowing quicker reactions and stiffer damper settings resulting in slower reactions.

That is because the damper absorb the energy that goes to or released by spring.

Scaff
However if a damper is set to stiffly for the spring rate then it will actually stop the spring from being able to react as quickly as it needs to and the force from the bump will be transferred through the suspension (which was not able to react quickly enough) and onto the car itself. The car will react as described above and if the force of impact with the bump is great enough then that corner/side of the car will loose contact with the ground.

Confusing, What do you mean transfered? The suspension suddently not moving? Looking at the suspension construction, can you explain using this picture?

Scaff
If a car in GT4 leaves the ground in a flat spin, then the system will allow it to gain altitude, however it does not reach a certain altitude and then stop. If you are saying that nothing will ‘force’ it back down then why does the car return to the ground?

It is definitely not because roll limiter bounce it back, but due to car weight being affected by gravitation simulation.

Scaff
To say that it just stops progressing is too state that the car will not return to the ground? It makes no sense.

It will only dampen the movement, not springing them. If the force depleted, it will go to whatever force still working.

Scaff
However it is quite clear that this is not what I have been discussing at all, I have consistently been talking about a situation where a car has one corner or side being forced up and the physics engine stopping it when a certain angle (in relation to the opposite side/corner) is reached, and again the car does not just stop at this point but returns to the ground.

I don't say that it hang's there. I wish my english is better, too many understanding from incorrect word. I mean to say it stop the rolling or pitching by dampening the kinetic energy too, not halted the car.

Scaff
The effect as I (and it appear most other people) see it is that it causes the car to bounce or jump from one side/corner to the other. This is GT4 coping with a situation from an over-stiff car that ‘should’ (in the real world) have flipped or rolled, but in GT4 is not allowed to.

I see, this is your explanation for car bouncing from higher value.
But you shouldn't forget that my previous roll experiment use PhD reference that state car roll is reduced by stiffer damper AND stiffer spring rate at bound and increased by stiffer damper AND stiffer spring rate at rebound.

Scaff
The Integra test has a direct and clear real world link, which is covered by all the Skip Barber info I have provided and the Physics of Racing piece on bumps. If two cars (one with softer damping and one with firmer damping) encounter the same bump at the same speed, then the one with softer damping will be better able to manage the bump than the firmer one. The firmer damped car is the more likely of the two (all other things being equal) to loose contact with the ground.

No it can go the opposite, both damper and spring rate has to be matched.

Scaff
Therefore logic will dictate that in GT4 the car that leaves the ground in the Integra test will most likely be the one with the firmer damper settings. As the car with the higher damper values lost contact with the track surface when it encountered the curb, it is logical to conclude that higher damper values in GT4 are firmer.

I believe testing it with different spring rate can give different result.

Scaff
However you’re tuning is not at question here, your understanding of dampers and the values used in GT4 is what is at question.

Ok.

Scaff
Also as has already been said, the amount (in length of suspension travel) is not principally determined by the damper rate. As long as the damper rates are not so firm as to limit the spring’s ability to react then when the throttle is released (all other things being equal) the load transfer would be the same. Therefore the amount of movement would not be affected by the damper; the damper would determine how quickly this movement occurred, but not how much movement will occur.

If damper help spring fight back the bump force, it can influence the suspension travel too.

Scaff
How then do you explain the Integra test, the difference in feel and handling, the significant change in feel and the clear difference in suspension reactions in the Caterham tests? None of these ‘fit’ your view of things, instead you devise very convoluted and overly complex theories (that do not match the real world in many cases) to ‘prove’ your point.

You should realize that your explanation about stiffer damper make the car jump more do not match the skip barber quote.

Scaff
First it’s a 14” set, now it’s a 21” set, which is it?

21", I have difficulty seeing it in 21", so I assume seeing it in 14" is close to impossible. You don't notice wheel vibration in your test so I assume you use something that is make it hard to see, like 14" set or LCD set or Plasma set or something. From what I see now, you just ignore it.

Scaff
Why is picking a value to use as a base value irresponsible? I fail to understand this; it’s a default value that as far as I can see you are the only person I have ever come across who has a problem with it. I also do not understand why you have such an issue with it; you can adjust it on the various suspension types. Again you have changed you’re comments on this, first you have an issue with the stock suspension settings and now you have no issue with them, so once again you’re being inconsistent.

Sorry, I forget that they have to simulate real car as first priority.
If PD use 2.0/1.0 camber for FC suspension, why don't they use 4.0/2.0 camber for stock car. If they want to mimic real car as close as possible why don't they use 0.0/0.0 camber for FC suspension too.
Original quote: "Just like PD fool us into thinking that 2.0/1.0 camber is the best combination because every road car with FC suspension have that value as default. And yet PD use 0.0/0.0 camber for every stock car, which is I think very unresponsible . If stock car has softer spring than FC suspension why they don't use camber value like 4.0/2.0 for it ?"

This can make people assume that we must use lower camber when we use softer spring. You all car expert so you should have no problem telling that this is only a blunder, what about people who don't know. That is irresponsible. That is not educating people. It fool people.

Congratulation to you all that was not fooled by this.

Scaff
Yes I understand that you still believe you are right, however you did not answer my question regarding everyone else’s thoughts, particularly this question.

https://www.gtplanet.net/forum/showpost.php?p=2216050&postcount=198
"Either that or they just don't care . I mean, thing like this is rarely discussed. If you find some weird thing you assume it's just another glitch and thinking lightly the word "funny, it shouldn't be like that" ."

Scaff
As I say, you may believe you are right, but very few other people agree, now either (as I asked above and before) everyone else is wrong, your copy of GT4 is different to every other copy released or you are wrong. So which one do you believe?

After you say the car can re jump more when using stiffer damper in real life Scaff, I believe my opinion more.
I really have a hard time believing that it's not a mistype.

So, do you ever discussed this thing in real life with real expert Scaff? Car can rejump higher because stiffer damper? Do you conclude it on your own or from someone or some book?

Dave_George · Apr 19, 2006

Sucahyo,

The original title of this thread was "Damper 10 is softer than 1"

You have had explained to you many times now, that most people feel this is NOT the case. Take any car in GT4 and drive comparison laps with low settings and hard settings and you WILL feel the difference. Its quite simple stuff really, most people would expect that on a scale of 1 to 10 that 10 would be the harder end of the scale, its how the other tuning elements of GT4 work!

You seem to enjoy persisting with this thread in the vein that everyone else is wrong and you are right, in the process you take the thread off on wild tangents to the point where we are talking about dropping cars from metres in the air.....its ridiculous quite frankly. You have quite possibly one of the most knowledgeable people on GTP giving you countless sources of information and explanations - and still it isnt enough. I added some comments from the point of view that I am no-where near as knowledgeable as Scaff but as an average driver I can use feel and give another perspective on the issue.

I think you need to re-visit the original title of the thread more and stop diverting off onto other things, and also you need to do more mileage in GT4, Drive more cars, drive more tracks and see if your thoughts are still the same on the original point you held in question. Im fed up with this thread now as I expect are some others and its due to you Im afraid.

regards

David

GT4 Dampers

Scaff

Dave_George

Scaff

sucahyo

Dave_George

Scaff

sucahyo

sucahyo

Mt. Lynx

GT racing!

sucahyo

T4 GTR

sucahyo

Scaff

sucahyo

Scaff

sucahyo

Mt. Lynx

GT racing!

sucahyo

Dave_George

Scaff

Mt. Lynx

GT racing!

sucahyo

Scaff

sucahyo

Dave_George

Mt. Lynx

GT racing!

sucahyo

Scaff

sucahyo

Dave_George

Similar threads

Latest Posts