GT4 Dampers

Badsight · Jan 23, 2006

edited , my bad

how the dampers are effecting the car is easy to see

dampers are there for spring control , they also effect other things - but dont worry about that

when thinking about the dampers - only focus on how your car seems to be riding on its springs , because keeping the springs under control is their job

your springs absorb bumps & cornering forces - your dampers smooth out your springs movement

sucahyo · Jan 23, 2006

Badsight
your springs absorb bumps & cornering forces - your dampers smooth out your springs movement

I think its damper job to absorb, while the spring follow the road contour.
spring hardness decide how fast it can keep up with the bump = osccilation frequency = bump frequency = faster speed need harder spring rate.
damper stiffness decide how much it nullify the force = faster speed need higher force nullifier to reduce zero overshot = more stiffness.

Badsight · Jan 23, 2006

the car sits on the springs

when the wheel travels over the roads surface & hits a bump - the spring absorbs this instead of it being transferred to the cars body

but springs bounce & pogo - they react too fast . dampers are there to slow & control the springs movements . they fight the springs to keep the wheel on the roads surface

adjust the dampers to suit your springs

sucahyo · Jan 23, 2006

Badsight
but springs bounce & pogo - they react too fast . dampers are there to slow & control the springs movements . they fight the springs to keep the wheel on the roads surface

adjust the dampers to suit your springs

Agree about fighting, damper brake the spring movement.
So, you also think harder spring rate also need stiffer damper?

Badsight · Jan 23, 2006

a strong spring can overpower a weak damper

stronger springs want stronger dampers to keeep their movement under control

im trying to keep my replys as simple as possible - if you can understand it simply - then you can problem solve on your own when you get an odd-behaving car

Badsight · Jan 23, 2006

remember - dampers are there mainly to keep the car settled on its springs - as the springs do their job of handeling the road & cornering

adjust your springs for handeling - then test drive it & see how bouncy it is , then your dampers to control your springs

sukerkin · Jan 23, 2006

Hi Badsight

It's been a while since the "Dampers are inverted in GT4" argument came up, so I suppose we were about due

.

I note that you certainly sound like you know what you're talking about but, altho' I wouldn't gainsay out-of-hand any of your points, I believe that you've reached an erroneous conclusion from the right observations.

An interesting note that you made was about the default values for the race suspension. I agree totally with your logic but PD has always had the default damper settings far too hard and the springs generally too soft in the GT series. They also have the anti-roll bars wound up a bit tight sometimes. I believe that this is down to the fact that the series was initially aimed at a Japanese market and those are the tuning algorithms they use (they iron out any handling problems it induces with tyre stagger).

I'm at work right now so I don't have time to go into this in detail. Take a look around this forum using the search function and you should be able to dig up quite a bit of discourse on the subject. However, if you find that you can tune the cars to your liking feeling that lower damper numbers mean stiffer dampers then I certainly wouldn't try to 'convert' you

.

Badsight · Jan 23, 2006

hello sukerkin

a test proved it to me , simple one too

we know that by default , compression is more important than rebound , a wheel kept under control in compression is less likely to get out of control on rebound , & also because the intial jolt of the bump is more powerfull than the rebound force of the spring

so in generall , its always best to have the Compression set a slight bit stronger than the Rebound - generally

in GT this is also reflected - set what you think is stiff dampers on compression & then a bit less on rebound - drive over bumps , then reverse the settings & see which combo was kept under controll better

i am seeing more controlled behaviour over bumps with compression set a lower number than rebound

& the opposite when compression is set a higher number than rebound

Scaff · Jan 23, 2006

@badsight Before I start on the subject of dampers may I welcome you to GTplanet. But could I also suggest that you stop posting messages one after the other. It makes the thread messy, difficult to read, even more difficult to quote and the mods really dislike it. You've done it twice now and its really is much easier to use the edit button.

Don't take it wrong, its just one of the things here at GTP, lots of people do it when they first join, so its no big thing (as long as you start to use the edit button).

OK onto dampers. First I have to say that I (and I suspect a lot of others) totally disagree with you, as you may be aware from the bulk of this thread.

Damper values in GT4 and every thing I have experienced with them and in comparison to real world damper activity does not agree with you're claim.

Before I get into why, please be aware that this is just about how the values work, not about how someone should tune. You should always tune to make a car work for you, even if everyone else hates it.

First if I may I'm going to use a quick Skip Barber quote with regard to how dampers of different strengths react.

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

Now every single observation and reaction I have had to suspension tuning in GT4 supports the above being true with lower values being softer and higher values being harder.

Take my tune for the Caterham Fireblade (a car that is very damper sensitive) which can be found over in the BESTuners thread.

Run the car at Deep Forest with that level of mods and the default damper settings (B8 / R8) and the car has a major problem with laying down traction over the surface changes, as the suspension struggles to keep the contact patch on the road (abrupt loading and unloading of the conatct patch). However with a much lower damper setting (as in the tune) the loading and unloading of the contact patch occurs much more gradually allowing the car to put its power down.

Looking at the same car and how it reacts to rumble strips, on the higher value setting the load is transfered almost straight past the suspension and causes the car to be physically forced off the road, its not a bounce at all. On lower values the suspension system can be seen to follow the surface changes of the runble strip, with the wheel moving visiable much quicker as the suspension moves much quicker.

If you now take a much heavier car, such as a two tonne Range Stormer with race suspension and set the dampers to a low value and drive over a rumble strip you will struggle to feel a thing, change the values to a much higher setting and now the rumble strip can be felt much more clearly.

All of the above point to damper settings being softer at lower values and stronger at higher values and I am yet to encounter anything in GT4 that would make me think any different.

read back through the thread and you will see that I have tested this in a number of ways and across the entire GT series.

Now don't get me wrong, you can of course set a damper to stiff or too soft for a particular car on a particulr track, and to a large degree damper tuning is a very personally thing, what suit one person may not suit another.

Badsight
we know that by default , compression is more important than rebound , a wheel kept under control in compression is less likely to get out of control on rebound , & also because the intial jolt of the bump is more powerfull than the rebound force of the spring

so in generall , its always best to have the Compression set a slight bit stronger than the Rebound - generally

in GT this is also reflected - set what you think is stiff dampers on compression & then a bit less on rebound - drive over bumps , then reverse the settings & see which combo was kept under controll better

i am seeing more controlled behaviour over bumps with compression set a lower number than rebound

& the opposite when compression is set a higher number than rebound

While I would agree with you that re-bound should generally be set higher than bound I don't agree with you're logic.

Just about every suspension document, manual or tuning I have read or spoken too will not agree that bound is more important than rebound. Quite the opposite, re-bound is the first area normally tuned. Take a look at most damper unit with single stage adjustment, what is it that can be adjusted, rebound.

As a tyre travels over a broken surface the contact patch needs to be able to react to it as quickly as possiable while remaining in contact with the road. A softer bound setting means that as load is applied it can be kept in contact with the surface, but the tyre also needs to be ready for the next bump, so you have to sacrifice some contact (rapid transfer of load from the contact patch) for a quicker return. Hence the higher rebound than bound value.

It doesn't (in my opinion) mean that higher = softer it just means that bound and rebound must be matched to the track. It also the reason why normally the difference between the two increases as tracks get bumpier.

I hope the above makes sense as It is difficult to explain.

In closing you should also be aware that the member you are discussing GT4 suspension tuning with, does not actually have GT4, but is instead refering to damper settings in GT2 (no offence sucahyo - but it is true).

Regards

Scaff

Badsight · Jan 23, 2006

hello Scaff , nice to converse with another person who likes to get fully into the game . i totally agree with the copy & paste of Skip Barber's words - & have been trying to say the same thing more simply to sucahyo

if the forces are the way you say they are in GT4 (GT3 & 2 are different to 4 ?) then the default damper settings are WAY too high for many cars - many cars are as you say - set with low spring rates & with the "8" setting damper

in GT4 - im seeing better behaviour over bumps & ripples with the compression set one number lower than the rebound - in generall

i would be interested in your thoughts on the Toe values - whether the + side numbers are inwards , or outwards pointing Toe .

(BTW , OT i know but the Clio V6 stumps me - when fully worked it just does not like to turn)

Scaff · Jan 23, 2006

Badsight
hello Scaff , nice to converse with another person who likes to get fully into the game . i totally agree with the copy & paste of Skip Barber's words - & have been trying to say the same thing more simply to sucahyo

if the forces are the way you say they are in GT4 (GT3 & 2 are different to 4 ?) then the default damper settings are WAY too high for many cars - many cars are as you say - set with low spring rates & with the "8" setting damper

in GT4 - im seeing better behaviour over bumps & ripples with the compression set one number lower than the rebound - in generall

i would be interested in your thoughts on the Toe values - whether the + side numbers are inwards , or outwards pointing Toe .

(BTW , OT i know but the Clio V6 stumps me - when fully worked it just does not like to turn)

No problem at all (the SKip BArber quote is fom his book Going Faster - highly recomend you get a copy it is truely excellent)

I do 100% believe that the damper values are high = stiff and would agree 100% that the default settings are way, way to stiff for the vast majority of cars. If you have a look at the GT4 tuning guide I have put together (thread at the top of this forum or click on the link in my sig) I say exactly that.

Its a bizzare default set-up and one that makes most cars a total nightmare out of the box.

Toe is an othe rgood one, my opinion on the subect is that - is toe in and + is toe out (same front and rear), this one has been discussed in the Official Allignment Values thread, it reaches a conclusion in the last few pages. Again this is also covered in my guide.

As I explained in my last post I would agree that most set-ups do require rebound to be a few 'clicks' higher than bound. It does depend on the car and track, but as a general rule of thumb it does work well. The exception are the rally tracks which require a much bigger difference, with re-bound much higher than bound.

You can see an exmaple of this in the Clio V6 set-up I did for both tarmac and gravel in the BESTuners thread, just click here. Give that set-up a try as well, the car is fairly much fully moded and I find it drives very well. You just have to remember its a car that needs a slow-in and fast-out approach.

Regards

Scaff

sucahyo · Jan 24, 2006

Badsight
so in generall , its always best to have the Compression set a slight bit stronger than the Rebound - generally

No, look at this koni shocks picture. compression value is lower than fixed or adjustable rebound value.

Badsight
i am seeing more controlled behaviour over bumps with compression set a lower number than rebound

I think this is because PD already incorporated different multiplier for bound and rebound.

Scaff
Run the car at Deep Forest with that level of mods and the default damper settings (B8 / R8) and the car has a major problem with laying down traction over the surface changes, as the suspension struggles to keep the contact patch on the road (abrupt loading and unloading of the conatct patch). However with a much lower damper setting (as in the tune) the loading and unloading of the contact patch occurs much more gradually allowing the car to put its power down.

Badsight, in these case if you think:
- 1 is softer, the suspension struggles to keep the contact patch on the road because the damper is too hard, making suspension not reacting to the road quickly enough
- 1 is stiffer, the suspension struggles to keep the contact patch on the road because the damper is too soft, making suspension over reacting to the road and create jump skipping.

Scaff
On lower values the suspension system can be seen to follow the surface changes of the runble strip, with the wheel moving visiable much quicker as the suspension moves much quicker.

Hey, didn't you agree to the opinion all GT show misleading visual damper effect?

Scaff
In closing you should also be aware that the member you are discussing GT4 suspension tuning with, does not actually have GT4, but is instead refering to damper settings in GT2 (no offence sucahyo - but it is true).

Yes.

Scaff · Jan 24, 2006

sucahyo
Hey, didn't you agree to the opinion all GT show misleading visual damper effect?

Not that I recall (and if I did I apologise), I said that visual information alone is not sufficent and that feel is also a critical part of tuning dampers.

In my post to badsight I advised he cover visual (the part you quoted); and two elements of feel, those of how well the car lays down traction and its reaction over rumble strips and how it can be felt.

Thats 2 to 1 for 'feel' over 'visual'. LOL

Regards

Scaff

sucahyo · Jan 24, 2006

Ok.
Stiffer front damper create more understeer doesn't count?

Updating first post to include summary.
BTW, I don't know if it's make any different for you knowing wether 255 damper is soft or stiff, but in GT4 255 damper is soft.

sucahyo · Mar 24, 2006

Recently my motorcycle rear shock busted again. Only this time I take more notice on handling difference.

The handling on uneven straight road is more unstable and noisy. The rear will vibrate, it slow the speed down sometime if I go too fast. The rear will not grip (braking or accelerating do not work effectively) if the vibration is too much. It will bouncing longer after a road bump.
The handling on uneven corner is dangerous even if it isn't raining. Tail slide can happen after the rear vibration become too much.

Since this experience is very rarely happen, I think only few of you has the experience of comparing zero damper and normal damper, because either you haven't live in a country with many bad road or you don't drive a very old car. Based on this experience:

the car behaviour that Scaff Caterham shows that 10/10 damper behave like a bit broken damper in real life, where 1/2 damper behave like working one. 10/10 damper shows the car slowing down and unstable because of vibration.
the car with lower damper should bounce/vibrate more in real life, in GT2 AND GT4 this represented with higher damper value.
the car with damper too low can jump in real life because accumulated vibration (I have seen it my self on big old truck passing uneven road). If the damper is too high the car will jump on the first bump.

My recent experience in 300mph attempt using R92CP also thaught me:

when using high damper (10/10 10/10) the car will nodd frequently (churchill effect?).
when using front or rear low damper (1/10 1/10 or 10/1 10/1) the car nodding only happen occasionally.
using lower damper can reduce nodding (slow bouncing) which mean lower damper have higher damper rate.

So, the above experience make me more stubborn

. Low damper value in GT2 AND GT4 is actually have higher damping power. You can try to convince me though, I might believe if it involve real life experience too

.

And remember, this will NOT make you change the way you tune your damper if you already doing it correctly.

Scaff · Mar 24, 2006

sucahyo
Recently my motorcycle rear shock busted again. Only this time I take more notice on handling difference.

The handling on uneven straight road is more unstable and noisy. The rear will vibrate, it slow the speed down sometime if I go too fast. The rear will not grip (braking or accelerating do not work effectively) if the vibration is too much. It will bouncing longer after a road bump.

The handling on uneven corner is dangerous even if it isn't raining. Tail slide can happen after the rear vibration become too much.

Sucahyo, sorry to hear that the back shockon your bike is bust again, sounds like its made it into an 'interesting' ride.

sucahyo
Since this experience is very rarely happen, I think only few of you has the experience of comparing zero damper and normal damper, because either you haven't live in a country with many bad road or you don't drive a very old car. Based on this experience:
the car behaviour that Scaff Caterham shows that 10/10 damper behave like a bit broken damper in real life, where 1/2 damper behave like working one. 10/10 damper shows the car slowing down and unstable because of vibration.

As I mentioned last time we discussed this point, haveing a totally shot damper is to a large degree the same as having no damper at all. The results and effects of a non-functioning damper can't be comparied to the reactions of working damper without knowing how its broken.

As an example a damper that is siezed solid would be broken, but have totally different characteristics to a leaking damper that was half empty. Both are broken, but their individualy reactions prove nothing.

Also leaking dampers can behave very strangely, as the changes in bound vs rebound characteristics can become very miss-matched.

sucahyo
The car with lower damper should bounce/vibrate more in real life, in GT2 AND GT4 this represented with higher damper value.

Sorry a real soft damper does not both bounce and vibrate, these are totally different characteristics. To use very general terms, soft damping allows more rapid suspension travel (with the springs controlling the degree of travel), the wheel can be seen to move. With hard damping the suspension reacts more slowly as the increased damping force resists the movement. If the damping level is set to high then the 'shock' from a curb or bump is transfered through the suspension (as the damper can not react quickly enough to absorb it) to the car chassis itself, which can then result in the tyre losing contact with the road.

sucahyo
The car with damper too low can jump in real life because accumulated vibration (I have seen it my self on big old truck passing uneven road). If the damper is too high the car will jump on the first bump.
[/list]

Again these are two different characteristics you are describing here, damping that is too soft (particularly with very soft springs) can set up accumulated vibrations that can cause the tyre to loose contact with the road.

And as you have said above, this is caused by accumulation over an uneven surface, not an encounter with the first bump.

The first is a product of low soft damping (often in conjunction with soft springs), the second is too firm damping not being 'fast' enough to cope with the bump.

Also remember that with very, very poor roads, sometimes the bump/hole is too large for even the softest suspension to mange. As someone who has a father who 'collects' Land Rovers & Range Rovers (currently owns a 109 carawagen conversion Landie and a Disco - has owned more that I care to remember) I've seen more than my share of big bumps and holes.

sucahyo
My recent experience in 300mph attempt using R92CP also thaught me:
When using high damper (10/10 10/10) the car will nodd frequently (churchill effect?).

When using front or rear low damper (1/10 1/10 or 10/1 10/1) the car nodding only happen occasionally.

Using lower damper can reduce nodding (slow bouncing) which mean lower damper have higher damper rate.[/list]

The issue with the R92CP is a littel different, because part of this is going to be the relation between downforce/springs and dampers. The GT4 physics at these speeds and the effect of downforce and lift are very, very basic to say the least.

As an example, I have watched thevideo of one of your 300mph runs, and the front of the car can be seen to rise, when this happens and air gets under a high-downforce car in reality. Well, it takes off (remember LeMans '99).

sucahyo
So, the above experience make me more stubborn . Low damper value in GT2 AND GT4 is actually have higher damping power. You can try to convince me though, I might believe if it involve real life experience too .

Again this is one we will have to agree to disagree on, a decade of working in the motor industry (which as you know has involved vehicle testing and training) leads me to believe that low values = soft and high values = firm in GT damper settings.

Again the one for me that clearly illustrates this in GT4 is how the damper settings react to the throttle in the Caterham test I did.

Lower values allowed the power to be layed down much more cleanly, which is a clear indication of the driven wheels being able to react to the weight transfer and loads under acceleration. Higher values made application of the power far more difficult, with much greater levels of skipping.

sucahyo
And remember, this will NOT make you change the way you tune your damper if you already doing it correctly.

And thats the most important point in this entire thread.

No matter what you or I (or anyone else) believes about this subject, as long as how someone is tuning is working for them, then they should keep doing it.

Regards

Scaff

sucahyo · Mar 25, 2006

Scaff
Sucahyo, sorry to hear that the back shockon your bike is bust again, sounds like its made it into an 'interesting' ride.

Yes

.

Scaff
As I mentioned last time we discussed this point, haveing a totally shot damper is to a large degree the same as having no damper at all. The results and effects of a non-functioning damper can't be comparied to the reactions of working damper without knowing how its broken.

My damper is leaking, so the result should be closer to zero damper rate. As the construction is simple I say both bound and rebound are affected.

Scaff
Sorry a real soft damper does not both bounce and vibrate, these are totally different characteristics.

It's possible. I use bounce term for slow large continuous up and down movement. I use vibrate term for rapid small continuous up and down movement. You are thinking that only hard damper can give you bounce, but in reality soft damper can too.
If the tire meet road slope?, the tire will force the spring to swing at minimum height. When we pass this slope the spring will make the tire move up and down slowly. If the damper is soft the movement will keep going longer. If at this moment we meet a bumpy road, we have both bounce and vibration at the same time.
Think of this as adding large amplitude low frequency sine wave with small amplitude high frequency sine wave. Hard damper will be faster in muting/silencing those.
In real life I only feel these when I carry passenger. The added weight make the ride swing up and down longer, even in this condition I still feel the road bump make the tire skipping continuously. This do not happen when the shock still normal, up and down swing is shorter, road bump do not make the tire skipping the road.

Scaff
Again these are two different characteristics you are describing here, damping that is too soft (particularly with very soft springs) can set up accumulated vibrations that can cause the tyre to loose contact with the road.

Yes, I mean that too soft damper jump after successive bump. Too hard damper jump after the first bump.

Scaff
As someone who has a father who 'collects' Land Rovers & Range Rovers (currently owns a 109 carawagen conversion Landie and a Disco - has owned more that I care to remember) I've seen more than my share of big bumps and holes.

I experience how it's feel climbing 80 degree rocky road in Bromo caldera before, so I understand the "sensation" a bit

.

Scaff
As an example, I have watched thevideo of one of your 300mph runs, and the front of the car can be seen to rise, when this happens and air gets under a high-downforce car in reality. Well, it takes off (remember LeMans '99).

Ok.

Scaff
Again this is one we will have to agree to disagree on, a decade of working in the motor industry (which as you know has involved vehicle testing and training) leads me to believe that low values = soft and high values = firm in GT damper settings.

Well, I don't have education for motor industry, I only tell what I feel in real life experience. And first hand experience stay in the brain longer, make you develop some kind of "trauma" :lol:

.

Scaff
Lower values allowed the power to be layed down much more cleanly, which is a clear indication of the driven wheels being able to react to the weight transfer and loads under acceleration. Higher values made application of the power far more difficult, with much greater levels of skipping.

Lower value simptom is exactly what I feel when the shock is normal, 60 kmph on sharp bumpy corner no problem. Higher values simptom is exactly what I feel after the shock oil is leaking, 40 kmph on sharp bumpy corner the rear goes skiping sideways :ouch:

.
If shock oil leaking = low damper rate then lower damper in GT4 = higher damper in real life.

If you are not agree please tell me why I am not suppose to think that the jiggle in caterham is not the same as the jiggle that I feel. Are you assume that happen because the damper is too hard? You don't have proof for that.

I think experiencing too hard damper in real life is close to impossible, because production car usually use underrate damper. You can only feel it in race car, but I am sure the technician will prevent that.

Scaff
No matter what you or I (or anyone else) believes about this subject, as long as how someone is tuning is working for them, then they should keep doing it.

Yes

.

sucahyo · Mar 27, 2006

I found reference that specifically explain about damper too stiff and too soft

http://www.sardesonracing.com/shock_tuning.htm
...
In practically all cases, when a car is set up "too stiff" the result is a race car that skates up the race track whenever bumps and ruts are encountered. Many drivers mistakenly describe this ill-handling as a "push" instead of a "skate". If the so called "push" only occurs over bumps and ruts, then the problem is a "skate" and softer shocks are usually the fix (assuming the springs are not too stiff).
When shocks are too soft and bumps are encountered, a cycle, referred to as "wheel hop" or "tire flutter" can occur. During wheel hop, the tire actually bounces on and off the track. The wheel hop cycle begins when a bump causes the suspension to move upward so violently that the tire leaves the track. This causes the spring to compress excessively and store a large amount of energy. Because the shock is too soft to control the energy stored by the spring, the tire is slammed back onto the race track. The tire bounces off the track again and the spring stores a smaller amount of energy. The cycle continues until the shock can control the energy level of the spring. The dreaded wheel hop can be caused by any major deformity in the racing surface or by violent rear axle wrap during acceleration or deceleration. Wheel hop can easily be felt by the driver and, if extreme, can be seen by those watching the race car. During wheel hop, the tire bounces up and down uncontrollably and causes the handling to be very unstable. The fix of coarse, is to install stiffer shocks.
...

Based on this higher damper value in GT4 is making the damper softer.

Scaff · Mar 27, 2006

sucahyo
Yes .
My damper is leaking, so the result should be closer to zero damper rate. As the construction is simple I say both bound and rebound are affected.

Sorry but that I can't agree with. How much has leaked? What type of damper is it (in terms of what is it filled with)? How it sustained any other type of damage? Unless you can test your damper on a dyno then you can't say that both bound and rebound have been effected, the only way to know for sure would be to test the damper. Hence my point that you can't say that a damaged damper acts like a soft one in all situations.

sucahyo
It's possible. I use bounce term for slow large continuous up and down movement. I use vibrate term for rapid small continuous up and down movement. You are thinking that only hard damper can give you bounce, but in reality soft damper can too.
If the tire meet road slope?, the tire will force the spring to swing at minimum height. When we pass this slope the spring will make the tire move up and down slowly. If the damper is soft the movement will keep going longer. If at this moment we meet a bumpy road, we have both bounce and vibration at the same time.
Think of this as adding large amplitude low frequency sine wave with small amplitude high frequency sine wave. Hard damper will be faster in muting/silencing those.
In real life I only feel these when I carry passenger. The added weight make the ride swing up and down longer, even in this condition I still feel the road bump make the tire skipping continuously. This do not happen when the shock still normal, up and down swing is shorter, road bump do not make the tire skipping the road.

I must confess that I'm not 100% sure what you are saying here.

sucahyo
Well, I don't have education for motor industry, I only tell what I feel in real life experience. And first hand experience stay in the brain longer, make you develop some kind of "trauma" .

My point was that my experience is with driving cars and then having to train people on the characteristic of the cars. I.E. real life, first hand experience.

sucahyo
If you are not agree please tell me why I am not suppose to think that the jiggle in caterham is not the same as the jiggle that I feel. Are you assume that happen because the damper is too hard? You don't have proof for that.

The effect I am refering to here is the loss of traction that occurs when the car goes over small imperfections and crests in the track (of which Deep Forest has many). Hard damper settings slow down the reaction of the suspension system, so if the car can gain less traction over these with a higher setting it indicates that higer values = firmer dampers.

Again (and I'm sure I have quoted this before) from Going Faster by Skip Barber

Going Faster
Expect that the shock settings for bumpier racetracks will have to be softer in order to allow the suspension to move faster enough to keep the tires in contact with the track surface.

With the Caterham example this can clearly be felt as the damper values are raised it is more difficult to lay down traction as the tyres struggle to keep in contact with the road surface. Lower the damper values and the suspension is able to react more quickly and the tyre struggle far less to keep the tyres in contact with the road.

sucahyo
I think experiencing too hard damper in real life is close to impossible, because production car usually use underrate damper. You can only feel it in race car, but I am sure the technician will prevent that.

That very much depends on the car and the market its being sold in, I've driven cars with (for road use) very stiff dampers. Remember that dampers that are fine for one road may well be far too hard for another road.

sucahyo
I found reference that specifically explain about damper too stiff and too soft
Based on this higher damper value in GT4 is making the damper softer.

Again I would have to disagree, this article is talking about the wheel moving so much that it leaves the road. This does not happen with high damper values in GT4, in fact with high damper values (again using the Caterham as an example) the wheel does not move. Instead the reason the wheel leaves the road is because the force of the impact with the curb is not absorbed by the damper and it forces the entire corner of the car to leave the road.

Regards

Scaff

Mt. Lynx · Mar 27, 2006

Simply see the values for damping in GT4 as pressure of whatever they are filled with. The higher the value, the more pressure you get, i.e high value = hard damping.

Scaff · Mar 28, 2006

OK this is quite nice and visual and may help

Here are a couple of pictures taken from the BTCC. I'm quite sure that given the nature of the cars and the ride height that they are quite clearly running that we would agree that the suspension setup is going to be on the stiff side.

We are seeing here what happens when stiff suspension settings encounter a curb on a track and the suspension can't react quickly enough to it. The force is transfered directly through the shock, which can't react quickly enough. This results in the corner, or in this case, side of the car lifting off the ground.

I then took out the Integra Type R Touring car in GT4, about the closest car to a BTCC car in the game. I then ran it over a curb with the dampers set to F3/3 & R3/3 and F10/10 & R10/10.

Damper F3/3 R3/3

Damper F10/10 R10/10

Now aside from the totally different feel of the cars, its quite clear to see that the car with the higher values damper settings is displaying the same characteristic on encountering a curb as the BTCC shots.

The car with the lower damper settings remains in conatct with the surface, while the higher damper setting causes the car to 'jump' on impact with the curb.

This, in my opinion, is yet more evidence that point to the higher damper values in GT4 being firmer settings.
Regards

Scaff

sukerkin · Mar 28, 2006

Excellent illustration Scaff 👍.

Why I didn't think of trying that is one of those un-answerable questions :lol:

.

sucahyo · Mar 28, 2006

Scaff
How much has leaked? What type of damper is it (in terms of what is it filled with)?

Oil filled damper (cheap). It seems all the oil is drained. Without oil there is no way bound and rebound not both affected. No other damage, just oil leaking because broken seal. Left and right is not broken at the same time. The left one broken after 1 week.
I just replaced it yesterday, and now I appreciate working damper more. It's more relaxing driving with normal shock compare to broken one.

Scaff
I must confess that I'm not 100% sure what you are saying here.

This:

Scaff
My point was that my experience is with driving cars and then having to train people on the characteristic of the cars. I.E. real life, first hand experience.

Are you saying:
You have experience driving same car with different damper rate setting in gravel (not just bump)?
or You have seen video that show car with different damper?
or You have seen tests that show damper being tested?

I drive car too, and there is plenty gravel/uneven surface road here. The road surface that behave like the above graph is exist too. I don't think you will be able to experience this in real life.

Scaff
The effect I am refering to here is the loss of traction that occurs when the car goes over small imperfections and crests in the track (of which Deep Forest has many). stiff damper settings slow down the reaction of the suspension system, so if the car can gain less traction over these with a higher setting it indicates that higer values = firmer dampers.

The barber skip is not wrong, but in GT4 you will never experience too soft or too stiff damper. So, you don't have to softer your damper in GT4, even the stiffest setting is still soft enough to allow the tire to keep contact with the road.

Scaff
With the Caterham example this can clearly be felt as the damper values are raised it is more difficult to lay down traction as the tyres struggle to keep in contact with the road surface. Lower the damper values and the suspension is able to react more quickly and the tyre struggle far less to keep the tyres in contact with the road.

That also happen when the damper is soft too. You just never experience it in real life yet. If you do please tell what happen when you drive a car with no damping on uneven road in real life.

Scaff
That very much depends on the car and the market its being sold in, I've driven cars with (for road use) very stiff dampers.

I only assume it from this

koni shock tech.pdf
Q: How much stiffer are KONIs than factory shocks?
A: This is a difficult question to answer because every KONI application is developed for that specific vehicle to get the best ride and handling characteristics. In general, most factory shocks are under damped for optimized handling so KONI engineers select firmer valvings. Unfortunately factory shocks are generally chosen for financial reasons rather than performance so lower technology, cheaper shocks are the standard. In some instances, a factory shock may have good characteristics in some parts of the working range but need some help in other parts and there are even a few instances where the KONI engineers found better handling by softening the factory units.

Scaff
Again I would have to disagree, this article is talking about the wheel moving so much that it leaves the road. This does not happen with high damper values in GT4, in fact with high damper values (again using the Caterham as an example) the wheel does not move.

How can you be sure that the wheel not move if seeing the wheel all the time in GT4 is impossible? I see it move more (a hint though) in your video.
On GT2 using 10 damper will certainly make the wheel more live.
This video show that 10 damper (top) have more wheel movement and more jump than 1 damper (bottom). Doing this in GT4 is impossible.

Team666
Simply see the values for damping in GT4 as pressure of whatever they are filled with. The higher the value, the more pressure you get, i.e high value = stiff damping.

That's real life. We can't do that in GT. That only work in GT1, as GT2 and GT4 (yes I test it at GT4 too) have opposite behaviour.

Scaff
Now aside from the totally different feel of the cars, its quite clear to see that the car with the higher values damper settings is displaying the same characteristic on encountering a curb as the BTCC shots.

The car with the lower damper settings remains in conatct with the surface, while the higher damper setting causes the car to 'jump' on impact with the curb.

This, in my opinion, is yet more evidence that point to the higher damper values in GT4 being firmer settings.

Nice picture

.
You are ommitting the possibility that those can also happen when you set the damper too soft. As I said before, you can not get too stiff damper in GT4 unlike in real life. Without seeing the video I can not be certain that the tire do not move an inch when meeting the bump. It is ALSO possible for the car to react like that if the damper is soft. The tire will react quickly but it reach it maximum moving range and the bump continue to raise the tire making it hit the car body very hard and make it jump. you also need to proof the tire do not move farther using higher value damper when the tire meet the bump. With only picture its hard to tell, so you can not use it to proof that higher value is actually harder.

I am aware seeing the tire all the time is impossible in GT4 replay. So, you can not proof this only with curb bump jump only.

Those BTCC picture show that when cornering the lateral force is so high that it can make the inside part jump only with small bump. When the car meeting thw bump the force of damper + spring delivered to the car body and make it fly.
Scenario:
1. soft damper soft spring, tire move quickly, if tire not exceed it's moving range the car will not jump.
2. soft damper hard spring, tire move quickly, if tire not exceed it's moving range and the spring not too hard the car will not jump.
3. hard damper soft spring, tire move slowly, if the damper is not too hard the car will not jump.
4. hard damper hard spring, tire move slowly, if the damper is not too hard and the spring is not too hard the car will not jump.

car can jump on many scenario, the damper doesnt have to be hard to make it jump.

Scaff · Mar 28, 2006

sucahyo
Oil filled damper (cheap). It seems all the oil is drained. Without oil there is no way bound and rebound not both affected. No other damage, just oil leaking because broken seal. Left and right is not broken at the same time. The left one broken after 1 week.
I just replaced it yesterday, and now I appreciate working damper more. It's more relaxing driving with normal shock compare to broken one.

I'm not disagreing that a leaking damper could effect both bound and rebound characteristics. What I am saying is to assume that bound and rebound have been effected equally by the leak is a huge assumption to make.

You have no way of knowing this at all, and short of dynoing the damper you (or I as I said) can't make assumtions about how its functioning.

sucahyo
Are you saying:
You have experience driving same car with different damper rate setting in gravel (not just bump)?
or You have seen video that show car with different damper?
or You have seen tests that show damper being tested?

I drive car too, and there is plenty gravel/uneven surface road here. The road surface that behave like the above graph is exist too. I don't think you will be able to experience this in real life.

I have driven cars with both adjustable dampers and done back to back comparisons between different cars on a wide range of surfaces (from smooth tarmac through to gravel, cobbles and Belgian Pave) at a number of different proving grounds.

I have also see video presentations (both marketing and techincal) of damper actions and reactions under different conditions, as well as dyno demos of damper set-ups.

Training in the motor industry is what I do for a living, so over the years I've worked with various elements of vehicle design and construction in order to be able to train dealership staff.

sucahyo
The barber skip is not wrong, but in GT4 you will never experience too soft or too stiff damper. So, you don't have to softer your damper in GT4, even the stiffest setting is still soft enough to allow the tire to keep contact with the road.

I'm sorry but that is complete rubbish. You are saying that suspension settings in GT4 do not allow you to lose contact with the road surface at all. Take a light car around the 'ring with default FC suspension setting and it very quickly becomes clear that its more than possiable.

sucahyo
That also happen when the damper is soft too. You just never experience it in real life yet. If you do please tell what happen when you drive a car with no damping on uneven road in real life.

Yes it is possiable for a softly damped car to lose contact with the road, but not generally becasue the suspension is unable to keep up with the changes in surface variation. This situation is normally more of an issue with lighter cars, particularly if they are running quite stiff springs (for the cars weight). However the feel of this is totally different that with a stiff car losing contact, and its also a lot less common.

The set-up I did for the Ginetta (you can find it in the BESTuners thread) at Deep Forest is a good example of this. With my set up (dampers 2/4 both front and back if I recall) it is possiable for the tyres to lose contact with the road over larger track irregularities or curbs, however the car is also quite stiffly sprung (for its weight) at the fornt end.

If you then change the dampers to say 8/10 front and rear (as I tried tonight) and run the car around Deep Forest, the car feels far stiffer and suffers from far greater problems with retaining conatct with the track over the curbs and surface variations. Additionally the car will now have far more of a problem remaining stable in the compression in the second tunnel.

All of these are problems normally associated with stiffly damped cars. If your claim that higher damper values were softer was true, then these issue should have been reduced by using a higher value. However they have not been reduced, far from it, the car is much more skittish around the track, more prone to losing grip and traction over surface iregulatities and less able to deal with the tunnel compression.

I have also pointed out a number of times before that a comparison with a car with no damping is not compariable to a car with damping. A totaly undamped car is traveling on springs only and would behavein a totally different manner to a car with any form of damping.

sucahyo
I only assume it from this

Which is a piece of sales information from Koni, please note how many times they cover themselves in it. Use of the words most, generally and some, these are far from definative statements. Manufactures standard damper units are sometimes poor quality and sometimes very high quality.

However the point I was making is that the dampers fitted to cars (and the settings they run at) vary from market to market.

Additionally some cars are sold as standard with very good dampers, a good example of this is the Renaultsport Clio Throphy, which comes with Sachs Race Engineering dampers fitted as standard or the '05 Lotus Exige that is fitted with 3 way adjustable Ohlins ST44 dampers as standard.

sucahyo
How can you be sure that the wheel not move if seeing the wheel all the time in GT4 is impossible? I see it move more (a hint though) in your video.
On GT2 using 10 damper will certainly make the wheel more live.
This video show that 10 damper (top) have more wheel movement and more jump than 1 damper (bottom). Doing this in GT4 is impossible.

Quite simply from watching the movement of the wheel from different angles and watching the reaction of the car itself, also from the feel of the car of the car itself.

GT2 videos are not really relevent to looking at this from a GT4 perspective.

sucahyo
Nice picture .
You are ommitting the possibility that those can also happen when you set the damper too soft. As I said before, you can not get too stiff damper in GT4 unlike in real life. Without seeing the video I can not be certain that the tire do not move an inch when meeting the bump. It is ALSO possible for the car to react like that if the damper is soft. The tire will react quickly but it reach it maximum moving range and the bump continue to raise the tire making it hit the car body very hard and make it jump. you also need to proof the tire do not move farther using higher value damper when the tire meet the bump. With only picture its hard to tell, so you can not use it to proof that higher value is actually harder.

I am aware seeing the tire all the time is impossible in GT4 replay. So, you can not proof this only with curb bump jump only.

Those BTCC picture show that when cornering the lateral force is so high that it can make the inside part jump only with small bump. When the car meeting thw bump the force of damper + spring delivered to the car body and make it fly.
Scenario:
1. soft damper soft spring, tire move quickly, if tire not exceed it's moving range the car will not jump.
2. soft damper hard spring, tire move quickly, if tire not exceed it's moving range and the spring not too hard the car will not jump.
3. hard damper soft spring, tire move slowly, if the damper is not too hard the car will not jump.
4. hard damper hard spring, tire move slowly, if the damper is not too hard and the spring is not too hard the car will not jump.

car can jump on many scenario, the damper doesnt have to be hard to make it jump.

First off you can have too firm damper settings in GT4 as I mentioned earlier, I strongly dispute any claim otherwise.

Secondly I have actually seen interviews with and spoken to BTCC techs, who have said that the main reason for the cars reaction in these circumstances is the firm suspension settings used. Having watched BTCC races live since I was a kid I also have a fair bit of personal viewing experience of this.

In regard to the pictures, what reason would I have to lie about them? The reason I used picture was to be able to quickly illustrate the point, its quicker and easier that a video upload (which would be from my digital camera and so not very high quality either).

The car did not leave the track surface with lower damper values, yet does leave the track surface with higher damper values.

Given the limitations of the GT4 physics engine I find it highly likely that this indicates higher = firmer (I did not say it proved it).

Finally while you are correct that it the real world it is possiable for this to occur with softer dampers, it is far more unlikely, and certainly not the reason why it is occuring in the BTCC shots.

Regards

Scaff

sucahyo · Mar 29, 2006

Scaff
What I am saying is to assume that bound and rebound have been effected equally by the leak is a huge assumption to make.

Ok. But you are agree that oil leaking reduce damping power right?

Scaff
Training in the motor industry is what I do for a living, so over the years I've worked with various elements of vehicle design and construction in order to be able to train dealership staff.

Ok.

Scaff
I'm sorry but that is complete rubbish. You are saying that suspension settings in GT4 do not allow you to lose conatct with the road surface at all. Take a light car around the 'ring with default FC suspension setting and the sheer absurdity of your statement very quickly becomes clear.

You are ommiting the possibility of soft damper can also cause that behaviour. If hacked value counted, using 20/20 20/20 damper can make you jump even on low spring rate.
I am not saying that GT4 do not allow you to lose contact with the road surface, I am saying that stiff damper (low value) in GT4 allow more contact to the road compare to soft damper (high value). In GT4 it is either:
- loose contact on stiff, ok if soft, your opinion (if lower is soft)
- loose contact on soft, ok if stiff, my opinion (if lower is stiff)

This is will never happen in GT4:
- loose contact on stiff, loose contact on soft, ok if just right (middle).

I am saying that in real life loose contact can happen in both too soft and too stiff. In GT4 you can only experience it if it is too stiff (or soft from my opinion).

you don't have proof for that, I can't proof it either. So, GT4 (also GT2 and maybe GT3) have medium to hard damper stiffness (or soft to medium damper stiffnes from my opinion).

Scaff
No it does not, softer dampers allow the suspension to move more quickly (this is not a subject of debate its a point of fact from the physics of what is occuring).

Yes, a damper will have higher damping power on higher frequency. Softer damper will allow longer spring movement.

Scaff
Yes it is possiable for a softly damped car to lose contact with the road, but not generally becasue the suspension is unable to keep up with the changes in surface variation. This situation is normally more of an issue with lighter cars, particularly if they are running quite stiff springs (for the cars weight). However the feel of this is totally different that with a stiff car losing contact, and its also a lot less common.

That is because you are assuming higher is stiffer. see above too.
I am trying to tell that what happen in GT4 is a softly damped car can lose tyre contact with the road, after a cycle of spring compressions and expansions that are not being controlled by the dampers. And believe in GT4, a stiffly damped car can loose tyre contact with the road, after first contact with bump, will NOT going to happen.

Scaff
If you then change the dampers to say 8/10 front and rear (as I tried tonight) and run the car around Deep Forest, the car feels far stiffer and suffers from far greater problems with retaining conatct with the track over the curbs and surface variations. Additionally the car will now have far more of a problem remaining stable in the compression in the second tunnel.

About stable thing, do you have any reference for the difference between too hard and too soft damper? Based on my previous quote, too soft is unstable, too hard is stable.

http://www.sardesonracing.com/shock_tuning.htm
Wheel hop can easily be felt by the driver and, if extreme, can be seen by those watching the race car. During wheel hop, the tire bounces up and down uncontrollably and causes the handling to be very unstable. The fix of coarse, is to install stiffer shocks.

So, this is surely soft damper reaction. 8/10 s softer than 2/4.

Scaff
All of these are problems normally associated with stiffly damped cars. If your claim that higher damper values were softer was true, then these issue should have been reduced by using a higher value. However they have not been reduced, far from it, the car is much more skittish around the track, more prone to losing grip and traction over surface iregulatities and less able to deal with the tunnel compression.

Its possible.
Your opinion, lower is soft, GT4 allow medium to hard:
- high is problematic, need to softer it.

My opinion, higher is soft, GT4 allow soft to medium:
- low is problematic, need to stiffer it.

So, we both improve our setting toward medium. We both think its correct. So the tuning procedure is same. We just using different perception.
But your opinion is wrong if when using high damper jumping happen because wheel cycling .

Scaff
I have also pointed out a number of times before that a comparison with a car with no damping is not compariable to a car with damping. A totaly undamped car is traveling on springs only and would behavein a totally different manner to a car with any form of damping.

Please explain why. From my view damper is a spring sine wave movement silencer. Without it spring will create infinite sine wave. A stiffer damper will silence it faster.

Scaff
Which is a piece of sales information from Koni, please note how many times they cover themselves in it. Use of the words most, generally and some, these are far from definative statements. Manufactures standard damper units are sometimes poor quality and sometimes very high quality.

Ok.

Scaff
Quite simply from watching the movement of the wheel from different angles and watching the reaction of the car itself, also from the feel of the car of the car itself.

We have different opinion for that, I think your high damper video have more movement. About feeling and reaction see my previous note about too soft and too stiff.

Scaff
GT2 videos are not really relevent to looking at this from a GT4 perspective.

Yes, just showing that doing this in GT4 is impossible.

Scaff
First off you can have too firm damper settings in GT4 as I mentioned earlier, I strongly dispute any claim otherwise.

This is from different perception. see above.

Scaff
Secondly I have actually seen interviews with and spoken to BTCC techs, who have stated that the main reason for the cars reaction in these circumstances is the firm suspension settings used. Having watched BTCC races live since I was a kid I also have a fair bit of personal viewing experience of this.

Ok.

Scaff
In regard to the pictures, what reason would I have to lie about them?

I am not saying that you are lying. I am saying that with no slow motion replay in addition of no constant wheel camera make us hard to notice any wheel movement, as it can occur in a split second. I notice this when creating my 350mph proof video, I have to keep press and depress pause button just to detect any wheel lift :crazy:

. If detecting wheel lifting is very hard to do, detecting fast wheel movement is impossible for me in GT4. So even when I can record GT4 video, detecting wheel movement will STILL be a big problem.
In other word, I am saying that you are not notice them. If you can, please tell me how, I can use it for my 300mph proof

.

Scaff
The car did not leave the track surface with lower damper values, yet does leave the track surface with higher damper values.
Given the limitations of the GT4 physics engine I find it highly likely that this indicates higher = firmer (I did not say it proved it).

see above.

Scaff
Finally while you are correct that it the real world it is possiable for this to occur with softer dampers, it is far more unlikely, and certainly not the reason why it is occuring in the BTCC shots.

Yes.

BTW, I still not clear about this

Scaff
The issue with the R92CP is a littel different, because part of this is going to be the relation between downforce/springs and dampers. The GT4 physics at these speeds and the effect of downforce and lift are very, very basic to say the least.

Please explain your view about the relation between nodding and damper. My view is:
- nodding can be reduced by lower damper, meaning lower is stiffer.
- as Toronado said softer spring is better, I think softer damper is better too.
- to get both reduced nodding and softer damper to help raising the front (just like spring) the optimum damper should be 10/1 1/10. The reason is I only stop nodding at front lowering, I am freeing the front rasing.
- I only confirm that damper reduce wheelie in GT2. Should my next attempt on R8 using this trick exceed my current 350mph record, I will consider this to be true.

Scaff · Mar 29, 2006

sucahyo
Ok. But you are agree that oil leaking reduce damping power right?

I’ve never said that the damping power would not be reduced, what I have said consistently is that the changes to both the level of bound and rebound can not be assumed or guessed.

It is possible through a leak that (for example) rebound damping was reduced by a much greater level than bound damping. This would not make the leak recreate an overall softer damper. Any assumption that a leak simply makes a damper act as if it’s softer is a gross oversimplification,.

sucahyo
You are ommiting the possibility of soft damper can also cause that behaviour. If hacked value counted, using 20/20 20/20 damper can make you jump even on low spring rate.
I am not saying that GT4 do not allow you to lose contact with the road surface, I am saying that stiff damper (low value) in GT4 allow more contact to the road compare to soft damper (high value). In GT4 it is either:
- loose contact on stiff, ok if soft, your opinion (if lower is soft)
- loose contact on soft, ok if stiff, my opinion (if lower is stiff)

Are you aware of just how soft a real world damper would have to be to allow contact loss of the nature you are describing?

Of the two possibilities that you are giving, only one matches general real world principals, and that the one of ‘loose contact on stiffer settings’.

I mean let’s take a look at the visible evidence in the world around us, you have said (and therefore I would assume agree) that most road cars are far more softly sprung that most race cars.

So a road car hitting a bump at speed (with its softer suspension settings) would jump all over the place. Yet we do not see this at all, I’ve tested road cars on Belgian Pave (a very, very bumpy surface) and those cars with soft suspension do not jump or lose contact with the road surface.

In contrast a race car (which by its very nature will be more stiffly sprung) will lose contact with the road surface when encountering a much smaller bump.

Real world logic, physics and observations do not support the proposal that a car is more likely to lose contact with the road surface if it is softly damped, so why would GT4 be set up like this?

sucahyo
This is will never happen in GT4:
- loose contact on stiff, loose contact on soft, ok if just right (middle).

I am saying that in real life loose contact can happen in both too soft and too stiff. In GT4 you can only experience it if it is too stiff (or soft from my opinion).

you don't have proof for that, I can't proof it either. So, GT4 (also GT2 and maybe GT3) have medium to hard damper stiffness (or soft to medium damper stiffnes from my opinion).

Sorry again I have to disagree with this, but to first clarify.

A car with any damper setting (softest through to hardest) is capable of losing contact with the road, it depends entirely on the nature of the bump encountered and the speed at which it is encountered.

However if a car hit a bump of a set height, at a set speed, the damper settings can determine how likely it is to lose contact with the road surface. This is because the damper settings control how quickly the dampers can react to the bump.

Given the example of a small bump hit by two cars (one with soft and one with hard dampers) both travelling at the same speed. The car with the softer dampers is less likely to lose contact with the road surface than the one with stiffer dampers. However if both these cars encounter a larger bump (or the same bump but at a higher speed) then they both may lose contact with the road surface, but the stiffly damped car is likely to suffer a much greater loss of contact.

Now while it is possible for a very softly damped car to be unable to fully control the cycle of its spring and lose contact with the road surface through uncontrolled spring expansion and contraction cycles, this generally will only occur if a car is travelling fast down a very uneven road, and does not occur quickly, as the car and suspension must normally go through a series of spring cycles before it will occur.

The above I do not need to prove, it’s how the physics of suspension systems work.

To put it into practice I ran a number of tests in Richard Burns Rally, which allows total control over Damper settings, the scale used in RBR is also real world values.

Setting a WRC spec Impreza to the stiffest possible damper settings and the car skips and jumps, losing contact with the road surface over even the smallest bumps.

In contrast setting the softest possible damper settings the car will only lose contact with the road surface after it encounters a large bump. It will also wallow around on poorly controlled spring oscillations, but this does not cause an immediate loss of contact with the road surface, rather it must build before the traction loss occurs.

The above test again supports low GT4 damper values being softer, and high GT4 values being stiffer. In fact the action, motion and feel of the stiff RBR setting was very similar to a high damper value in GT4.

sucahyo
Softer damper will allow longer spring movement.

Only if the spring rate allows a longer range of movement.

sucahyo
That is because you are assuming higher is stiffer. see above too.
I am trying to tell that what happen in GT4 is a softly damped car can lose tyre contact with the road, after a cycle of spring compressions and expansions that are not being controlled by the dampers. And believe in GT4, a stiffly damped car can loose tyre contact with the road, after first contact with bump, will NOT going to happen.

For the reasons I have outlined above I totally don’t agree with this.

sucahyo
About stable thing, do you have any reference for the difference between too hard and too soft damper? Based on my previous quote, too soft is unstable, too hard is stable.
So, this is surely soft damper reaction. 8/10 s softer than 2/4.

What I am referring to here is the stability of the car over surface irregularities. In the real world when a car is running on a bumpier track (which Deep Forest is) it would run softer damper settings to ensure that the suspension was able to react quickly enough to the surface changes and maximise the amount of time the tyres remain in contact with the road. This is not an area subject to speculation, it is what happens in the real world (either that or you are claiming that the instructors at he Skip Barber racing school are wrong). In the real world a car with stiff dampers is not better able to deal with bumps, softer damper settings are required.

When running the Ginetta at Deep Forest the car is far better able to deal with the surface bumps and is more stable over these bumps with lower value settings, which quite clearly points towards lower values being softer.

sucahyo
Its possible.
Your opinion, lower is soft, GT4 allow medium to hard:
- high is problematic, need to softer it.

My opinion, higher is soft, GT4 allow soft to medium:
- low is problematic, need to stiffer it.

So, we both improve our setting toward medium. We both think its correct. So the tuning procedure is same. We just using different perception.
But your opinion is wrong if when using high damper jumping happen because wheel cycling .

I agree that we both achieve the same aim in tuning, but I disagree that higher values are causing jumping because of ‘wheel cycling’. If you are describing the oscillation of the springs caused by under-damping as ‘wheel cycling’ then this is incorrect, the phenomenon off under-damped oscillation does not occur in quick cycles, but slow ones. The spring is not totally uncontrolled (that would require no damping to happen at all and would be rapid cycles), but is under-controlled, the damping effect is still present but is not strong enough to stop the cycle happening. It does however slow the cycle down, causing a very characteristic ‘boat’ like wallowing effect on the car.

I have never seen this effect occur in GT4 (or any of the GT series), but was very clearly visible in very soft damper test I carried out in Richard Burns Rally.

sucahyo
Please explain why. From my view damper is a spring sine wave movement silencer. Without it spring will create infinite sine wave. A stiffer damper will silence it faster.

See my last point.

sucahyo
I am not saying that you are lying. I am saying that with no slow motion replay in addition of no constant wheel camera make us hard to notice any wheel movement, as it can occur in a split second. I notice this when creating my 350mph proof video, I have to keep press and depress pause button just to detect any wheel lift . If detecting wheel lifting is very hard to do, detecting fast wheel movement is impossible for me in GT4. So even when I can record GT4 video, detecting wheel movement will STILL be a big problem.
In other word, I am saying that you are not notice them. If you can, please tell me how, I can use it for my 300mph proof .

And as I said above, if this was caused by under-damped springs oscillating then it would have been clearly visible. Additionally, while exact wheel movement is difficult to see in closed wheel cars (why I used the Caterham in other tests) the entire side of the car leaving the track surface is very easy to see. This occurred far more with the higher values settings than the lower values settings, its easily repeatable and to me a very clear indication of higher values being firmer.

It once again ties in with the real world fact that, all other things being equal, firmer damper settings are more likely to cause a loss of contact with the road surface than soft damper settings when the car encounters a bump.

sucahyo
BTW, I still not clear about this
Please explain your view about the relation between nodding and damper. My view is:
- nodding can be reduced by lower damper, meaning lower is stiffer.
- as Toronado said softer spring is better, I think softer damper is better too.
- to get both reduced nodding and softer damper to help raising the front (just like spring) the optimum damper should be 10/1 1/10. The reason is I only stop nodding at front lowering, I am freeing the front rasing.
- I only confirm that damper reduce wheelie in GT2. Should my next attempt on R8 using this trick exceed my current 350mph record, I will consider this to be true.

In my personally opinion the effect of high speeds on the GT physics engine causes some very strange results, its an area I would want to carry out far more tests on before commenting on. I can however say that he effects of down-force and aero on cars at high speed in GT4 only bear a basic similarity with what happens in the real world. Which is not surprise as the subject of aerodynamic engineering in motorsport is incredibly complex.

What you also seem to be ignoring is that lower damper values act more like a car with no suspension mods fitted. Now I think that every-one agrees that with most cars the default suspension is overall softer than the sports suspension, which is softer than than the semi-racing which is softer than the FC suspension.

Now if that is true and the lower values on the FC suspension cause suspension travel movements that are more like those caused by the stock suspension, then that would again indicate lower = softer. To put this to the test I ran a Dodge Challenger with stock suspension and then with FC suspension set to F&R 1/1 and F&R 10/10.

The F&R 1/1 settings on the FC suspension certainly had more in common, both visually and through feel with the standard suspension, than the F&R 10/10 settings did.

Don't get me wrong, you would expect the 'softest' FC settings are still be firmer than the stock suspension, but the F&R 1/1 are the closest ones to stock, both visually and in terms of feel

Regards

Scaff

Dave_George · Mar 29, 2006

I have been keeping an eye on this thread as its become quite entertaining, however I would like to add my thoughts, purely based upon 17 weeks of racing on the bumpiest circuit on GT4, The Nurburgring.

We used a variety of cars and all levels of suspension tuning.

I found that I had to lower the damping settings for every car we used, regardless of the suspension being sports, semi-race or race I found that higher values for damping settings = a nervous twitchy car that wasnt in control over the bumps as much as a car with lower damping settings.

Now I have no data to back this up, this is purely from a "Feel factor" but all I will say is that I was consistent through the series and at no point have I thought that lower damping - is stiffer than higher damping, the scales used in the tuning screens make some sense at least (while not being perfect) and are quite self explanatory for me anyways...

regards

David

sucahyo · Mar 31, 2006

Scaff
Any assumption that a leak simply makes a damper act as if it’s softer is a gross oversimplification.

Then, from your point of view, can you explain what happen to my bike shocks? And why it behave like that?

Scaff
I mean let’s take a look at the visible evidence in the world around us, you have said (and therefore I would assume agree) that most road cars are far more softly sprung that most race cars.

Yes I agree road car damper is under damped, but I am not saying those car have damper soft enough to experience jump after suspension cycling. It is not too soft.

Scaff
Yet we do not see this at all, I’ve tested road cars on Belgian Pave (a very, very bumpy surface) and those cars with soft suspension do not jump or lose contact with the road surface.

You notice softer damper have longer up and down movement right? unlike your celica. I am sure your celica pass those road better (more stable), but I think it will send more vibration to the driver. If it doesn't either your spring is too stiff or your damper is not stiff enough.

Scaff
Real world logic, physics and observations do not support the proposal that a car is more likely to lose contact with the road surface if it is softly damped, so why would GT4 be set up like this?

No, you still don't have proof/reference about damper too stiff can make the car unstable.And even with cheap material manufacturer surely prevent car unstability from too soft damper.

Aside from this link I found another link explaining that car is unstable if using damper too soft.

http://iroland.uw.hu/html/F1%20Car%20Setup.htm (game too?)
If you know that your car is unstable through the corners then you probably want to stiffen the dampers (increase the values).

http://www.strappe.com/suspension.html
We've all seen cars with bad shocks, pogoing their way down the freeway. A wheel hits a bump and compresses, then rebounds, then re-rebounds, maybe as many as three or four times. This is oscillation and it can make a car (or a bike) nearly impossible to control.

This is where shocks (or, more correctly, spring dampers) come in. The damper is partially filled with oil which is forced through small orifices when the fork (or rear shock) compresses and rebounds. The friction of the oil through these passages retards the movement of the suspension, taking energy from the spring and transferring it to the oil as heat.

You can get a feel for good damping by bouncing on the seat of a well-set-up sportbike, motocrosser or racebike. Bounce on the seat and stand up immediately - you'll feel the bike rise quickly to almost full height, then slow down the last bit of travel. Often you can feel the same thing when compressing the forks. That's damping in action.

http://www.stockcarproducts.com/cshocks9a.htm
Wheel hop can easily be felt by the driver and, if extreme, can be seen by those watching the race car. During wheel hop, the tire bounces up and down uncontrollably and causes the handling to be very unstable. The fix, of course, is to install stiffer shocks. Keep in mind that wheel hop to any degree, whether felt by the driver or not, reduces traction.

http://www.ikonsuspension.com/content/ikon-sol.html bike
If a suspension is under-damped it may feel unpleasant, but it will not be unsafe as long as the driver takes it easy. However, if ridden hard, a bike with incorrect damping will be unstable, especially when cornering.

http://wotid.com/tls/content/view/22/53/
Too hard - as a rule, if the damping is too hard, the bike will feel unstable. If it's too hard in the compression damping the suspension will not comply with bumps, as the transferring of the force is too slow, meaning the wheel will tend to skip over the top of the bumps rather than follow the contour of the road surface. If too hard in the rebound damping the bike will tend to 'pack down' or 'squat'. This is caused by the suspension not allowing the bike to rise back up to its original position quickly enough. The end result of this is sometimes referred too as suspension "chatter." Although the bike will feel unstable, it will tend to feel quite 'stiff' or 'taught.'

Too soft - the interesting thing here is that if the damping is too soft, the bike will also feel unstable. Only this time, rather than 'chattering' it will tend to feel 'sloppy,' and possibly 'wallow' in corners. (wallowing means that the suspension will oscillate without anything seeming to start it off, like bumps for example) It may also feel a little like a pogo stick, continuing to transfer the force up and down the length of the travel. This is particularly noticeable on bikes that have done a lot of miles.

http://old.bemsee.net/tech/setup.html
Too little rebound damping can cause:
- The rear "tops out" too fast under braking, causing the rear wheel to jump
- The bike feels unstable.

http://www.sentra.net/tech/garage/suspension.php
Car oscillates due to under damped spring motion, like a boat, car get twitchy in turns, feels unstable.

http://www.melroset-tops.com/wheel_alignment.htm
Car Is Unstable / Unpredictable
Too much toe out at rear wheels
One or more shocks gone bad
Front toe out whacked (would have to be way too much or way too little)
Check for broken or worn parts

irrelevant link but show how to tune damper

Only 1 of them mention unstability cause by damper too stiff , majority say it's damper too soft fault.
I'll wait for your reference.

Scaff
Now while it is possible for a very softly damped car to be unable to fully control the cycle of its spring and lose contact with the road surface through uncontrolled spring expansion and contraction cycles, this generally will only occur if a car is travelling fast down a very uneven road, and does not occur quickly, as the car and suspension must normally go through a series of spring cycles before it will occur.

I only need 30mph in concrete road to feel the vibration in my previous bad shocks.

Scaff
Setting a WRC spec Impreza to the stiffest possible damper settings and the car skips and jumps, losing contact with the road surface over even the smallest bumps.
In contrast setting the softest possible damper settings the car will only lose contact with the road surface after it encounters a large bump. It will also wallow around on poorly controlled spring oscillations, but this does not cause an immediate loss of contact with the road surface, rather it must build before the traction loss occurs.

This means you can't experience too soft damper in Richard Burns Rally.

Scaff
Originally Posted by sucahyo, Softer damper will allow longer spring movement.
Only if the spring rate allows a longer range of movement.

I mean the suspension will move in longer period of time.

Scaff
What I am referring to here is the stability of the car over surface irregularities. In the real world when a car is running on a bumpier track (which Deep Forest is) it would run softer damper settings to ensure that the suspension was able to react quickly enough to the surface changes and maximise the amount of time the tyres remain in contact with the road.

Softer is not too soft. If you use 5% of that softer damper, you will experience it.

Scaff
When running the Ginetta at Deep Forest the car is far better able to deal with the surface bumps and is more stable over these bumps with lower value settings, which quite clearly points towards lower values being softer.

More stable doesn't mean more softer.
To correct slow steering response / snap which do you prefer:
10/1 10/1 or 1/10 1/10

I choose the later one. This works for me, I am thinking that snapping is reduced because front have stiffer damper and make it tighter.

Scaff
I agree that we both achieve the same aim in tuning, but I disagree that higher values are causing jumping because of ‘wheel cycling’. If you are describing the oscillation of the springs caused by under-damping as ‘wheel cycling’ then this is incorrect, the phenomenon off under-damped oscillation does not occur in quick cycles, but slow ones. The spring is not totally uncontrolled (that would require no damping to happen at all and would be rapid cycles), but is under-controlled, the damping effect is still present but is not strong enough to stop the cycle happening. It does however slow the cycle down, causing a very characteristic ‘boat’ like wallowing effect on the car.

No. I experience both in my bike. Are you saying car suspension can't experience it? Are you saying that the same type of damper will work differently if it's used in car?
I don't understand your logic why too soft can't have rapid cycle, or no damping can't have slow cycle. If the road force it to do that what happen then? Too soft is not the same as road car soft. If soft damper can't have rapid cycle then it is NOT too soft.

Scaff
I have never seen this effect occur in GT4 (or any of the GT series), but was very clearly visible in very soft damper test I carried out in Richard Burns Rally.

That means in RBR we can use much softer damper than in GT.

Scaff
And as I said above, if this was caused by under-damped springs oscillating then it would have been clearly visible. Additionally, while exact wheel movement is difficult to see in closed wheel cars (why I used the Caterham in other tests) the entire side of the car leaving the track surface is very easy to see.

It don't have to oscilate first. Jump can be caused by the spring momentum too. Where stiffer damper has less momentum than softer damper (I explain if you need it), so it jump lower. Try with different speed.

Scaff
It once again ties in with the real world fact that, all other things being equal, firmer damper settings are more likely to cause a loss of contact with the road surface than soft damper settings when the car encounters a bump.

Agree, but of course not unstable.

Scaff
In my personally opinion the effect of high speeds on the GT physics engine causes some very strange results

So you can't explain why nodding is reduce when damper is lowered?

Scaff
What you also seem to be ignoring is that lower damper values act more like a car with no suspension mods fitted. Now I think that every-one agrees that with most cars the default suspension is overall softer than the sports suspension, which is softer than than the semi-racing which is softer than the FC suspension.

I don't, I just think it's irrelevant. Stock Skyline GTS-T type M has 2.4/2.1 spring rate, which I think is half of what sport (double?), semi(tripple?) and FC suspension minimum. So any damper value should give closely same behaviour.

Scaff
Now if that is true and the lower values on the FC suspension cause suspension travel movements that are more like those caused by the stock suspension,

It is not.

Dave_George
I found that I had to lower the damping settings for every car we used, regardless of the suspension being sports, semi-race or race I found that higher values for damping settings = a nervous twitchy car that wasnt in control over the bumps as much as a car with lower damping settings.

We have to wait for proof that too stiff damper indeed make the car unstable, I found more reference told that it is too soft damper behaviour.

Dave_George
Now I have no data to back this up, this is purely from a "Feel factor" but all I will say is that I was consistent through the series and at no point have I thought that lower damping - is stiffer than higher damping

I am sure that you feel all lowest damper have faster reaction than all highest one right? I feel all highest more sluggy at slalom. How do you feel about this? And you view about what make it behave like this?

Dave_George
the scales used in the tuning screens make some sense at least (while not being perfect) and are quite self explanatory for me anyways...

In real life the value of damping also measured from 1 to 10, 1 is usually softest, but sometimes it doesn't (depend on manufacturer). sorry, I forget the link, but I mention this in here before.

Dave_George · Mar 31, 2006

sucahyo
I am sure that you feel all lowest damper have faster reaction than all highest one right? I feel all highest more sluggy at slalom. How do you feel about this? And you view about what make it behave like this?

....Hmmm, If I was to remove a damper from a car that had been set to "10" I would imagine it would be hard for me to compress, compared to say a damper that had been set to "1" - If I was to then drive a car with Dampers set to 10 through a slalom on smooth tarmac I would imagine it would respond to steering inputs quite quickly and drive quite good, I would imagine a car with soft damping would respond slower and be more "sluggish" as you term it, however the car with damping set softer would handle better on a bumpy circuit in my experience.

I will try in a test what I just mentioned to confirm my theory.👍

regards

Dave

Scaff · Mar 31, 2006

sucahyo
Then, from your point of view, can you explain what happen to my bike shocks? And why it behave like that?

NO, for the reasons I have now repeated more times than should be needed (and is actually covered in the 'how to tune a shock' link you provided), damaged shocks act in an unpredictable manner and as such you can't assign particular handling characteristics to them in comparison to a functioning damper.

sucahyo
Yes I agree road car damper is under damped, but I am not saying those car have damper soft enough to experience jump after suspension cycling. It is not too soft.

I don't recall saying they were, I was illustrating my point with real world examples.

sucahyo
You notice softer damper have longer up and down movement right? unlike your celica. I am sure your celica pass those road better (more stable), but I think it will send more vibration to the driver. If it doesn't either your spring is too stiff or your damper is not stiff enough.

No, softer dampers will only allow more up and down movement if the spring rate allows it. While dampers do have a strong influence over the length of travel, it is still primeraly controled by the spring rate.

In my own Celica I have experienced loss of traction from a wheel losing contact with the road when driving hard over a poor road. I've driven the same road in a more softly damper car and not lost tyre contact with the road at similar speeds.

However according to you I must be imagening this, as it does not 'fit' with your belief of how dampers work.

sucahyo
No, you still don't have proof/reference about damper too stiff can make the car unstable.And even with cheap material manufacturer surely prevent car unstability from too soft damper.

What......

...you mean apart from the quotes I have already supplied over the pages of this thread and others on the subject. However here we go again.

The Skip Barber Racing School - Going Faster p210
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

Only one quote you may say. Yes, but in this instance its quality not quantity, the Skip Barber race school and it instructors and techs wrote the Going Faster race guide. It is considered one of the world definative texts on racing. It quite clearly states that too still dampers on a bumpy track will lead to a loss of tyre contact withthe road, and as it sayd tyres that are not in contact with the road don't provide much grip. A car that can't provide grip is not going to be particularly stable.

It would also appear that my own experience on training this subject is being dismissed by you. So in a similar vein to your question earlier, may I ask what experience you have in this field?

sucahyo
This means you can't experience too soft damper in Richard Burns Rally.

Have you played Richard Burns Rally?

If so, then fine that is your opinion. If not please explain what exactly you are basing that statement on, because RBR allows damper settings that are far to soft for the car.

sucahyo
No. I experience both in my bike. Are you saying car suspension can't experience it? Are you saying that the same type of damper will work differently if it's used in car?
I don't understand your logic why too soft can't have rapid cycle, or no damping can't have slow cycle. If the road force it to do that what happen then? Too soft is not the same as road car soft. If soft damper can't have rapid cycle then it is NOT too soft.

Dampers on nikes and cars do function in the same basic way, but the forces and distribution of weight during travel and cornering are very different.

Also I said that damping will slow down the cycle in comparison to a totaly undamped spring.

sucahyo
That means in RBR we can use much softer damper than in GT.

I believe I said that, but you have not answered or adressed the point I made in regard to the hard settings on RBR behaving in a similar manner to the high values on GT4.

sucahyo
So you can't explain why nodding is reduce when damper is lowered?

I'm sorry but did you deliberatly ignore the fact that I said I would have to test this before I commented?

sucahyo
I don't, I just think it's irrelevant. Stock Skyline GTS-T type M has 2.4/2.1 spring rate, which I think is half of what sport (double?), semi(tripple?) and FC suspension minimum. So any damper value should give closely same behaviour.

It is not.

So now only spring rate has an effect?

Damping values are very, very different between stock cars and cars with FC fitted. Try the car I mentioned and see if you still think damper values are unchanged.

sucahyo
In real life the value of damping also measured from 1 to 10, 1 is usually softest, but sometimes it doesn't (depend on manufacturer). sorry, I forget the link, but I mention this in here before.

Since when? All damper manufacturers use guides of there own, normally so many 'clicks' up and down from a zero point, not a 1 to 10 scale.

Additionally when dynoed dampers are specifically measured on whatever force scale is correct for the country in question.

I closing I have to say that your reply here has actually ignored a lot of what I said in my post and you seem to be happy to dismiss out of hand any evidence that does not support what you believe should be correct.

You seem to totally dismiss the fact that a car can lose control is dampers are set too firmly for a bumpy track!! State that the firmer you set a damper the more stable a car will be (which is true on a perfect track - but few tracks are perfect) which again is not always true.

I have maintained all along that too soft or too hard dampers will cause a problem, I also have said that a correct 'middle' point is needed to tune a car for a track.

I base my view that lower is soft on a wide range of evidence and experience (not all trawled from the web), I do have to ask exactly what expereince you have in the real world of driving different cars, on different dampers to dismiss out of hand my own perspective.

Regards

Scaff

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GT racing!

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