GT4 Dampers

[sucahyo]

Ok, I accept that my post is incomplete, I will complete my post.

I don't think that quote explain your solution for lift off understeer/oversteer. My post in that quote explain how I try to cure problem during apply throttle not lift off throtle although coincidentally both has the same problem for mentioned car. I think there could be car that both have opposite problem, maybe like MR2, where I detect the car have apply throttle understeer and lift off throttle oversteer.

Since most post that I read talk about lift off throttle problem, I suggest to find the solution of lift off throttle problem first.


I hope this is complete, if not tell me what is missing.
My conclusion:
To reduce lift off oversteer, reduce front bound value and/or increase rear rebound value.
To reduce lift off understeer, increase front bound value and/or reduce rear rebound value.

This conclusion is taken from experience tuning for GT4 tuning competition week 9 (Ford GT '05 @ Trial Mountain), week 11 ( Pagani Zonda C12S @ Autumn Ring), week 13 (Hyundai Tiburon @ Grand Valley) and week 14 (Holden Monaro @ Tokyo R246).


I use 10/1 10/1 in Ford GT '05 to reduce lift off understeer. full setting here. GT4 TC result here

I use 10/7 10/7 in Pagani Zonda to reduce lift off understeer a little. full setting here. GT4 TC result here


I use 7/10 7/10 in Hyundai Tiburon to reduce lift off oversteer a little, but turn out to be not neccessary. Full setting here. GT4 TC result here


I use 10/1 10/1 in Holden Monaro to reduce lift off understeer. Full setting here. GT4 TC result here

 

[Scaff]

Dampers – A Test

After playing around with my Caterham from the recent tune session I thought I would see if we could use it once again to look at damper stiffness.

Now it’s important to understand the following prior to running this test (and I would love as many people to do it as possible).

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

and

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.

The Car
Now the test itself involves a Caterham Fireblade with very specific FC and Ballast settings.

Spring Rate – Minimum front and rear – As spring rates have a major effect on how far the suspension moves under load I have set these to the lowest values to ensure that the maximum visual movement is available.

Ride Height – Maximum front and rear – The greater the ride height the greater the load that will be transferred, so these go to the max, again to ensure that we have lots of movement.

Dampers – These will be set to either all 1 or all 10 (both front and rear & bound and Rebound) for the two parts of the test.

Stabilisers – Minimum front and rear – In an ideal world I would like to remove these from the test totally, but GT4 does not allow us to do so. Stabilisers effectively act as springs during lateral load transfer (but not during longitudinal transfer) so they need to be set as low as possible to reduce the effect they have.

All other FC Suspension settings are left at default as they will not have a major impact on the test.

Ballast – Location = -50 (full front)
Ballast – Weight = 200 (maximum)
The ballast settings are present to ensure that the very visible front end of the Caterham has as much load moving around (particularly under braking) as possible.

Tyres – R3 – Soft race tyres are used to ensure that grip is maximised throughout the test, this will again ensure that the most is asked of the suspension, particularly under braking.

The reason for the above settings is the maximise the visual side of the test, and this should allow us to see as best we can what is occurring, when combined with the feel and noise side of things I hope this will provide a better understanding of damper settings.



The Track
Motorland was chosen based on a couple of factors, it’s short and has good lighting to allow the front end of the car to be seen easily. Most importantly it features a lot of corners in quick succession which demands lots of braking and accelerating.


How to run the test
Try and maintain good clean consistent runs with each damper setting, but I would encourage trying a range of differing driving styles for each. Highly recommended is a run using only straight-line braking and compared with trail-braking runs.

The most important factors are to keep in mind both feel and sound as you run, and riding over a few rumble strips is strongly recommended. Do take care with the car, as a ballast of 200 right out the front of a car as (normally) light as the Caterham (and mine was fully weight reduced to start) makes it more than a little nose heavy.

When playing the replays back (which is important for the visual element here) as soon as it starts playing hit the ‘X’ button to get the ‘in-car view’ and then use ‘R1’ to switch to the low chase cam and then use ‘L1’ to get a reverse view. This gives a very clear view of the front suspension in action.



Results – Dampers all 1
Feel – Well lets be honest given the low curb weight of the Caterham (even with the ballast) the cars never going to feel smooth around a track, but the car does feel compliant and the front end does feel quite eager and willing to roll as you change direction, accelerate and brake. Running over the rumble strips the vibrations are of course present, but they are relatively soft and feel slightly ‘smoothed’. Even when you trail brake into a corner the roll is very present.

Noise – This can mainly be judged over the rumble strips and while of course present is of a softish quality and sounds like you are blowing a raspberry (http://www.devilducky.com/media/54954/).

Visual – As soon as load begins to transfer the suspension can be seen to move and while this is evident over the rumble strips and other curbs, it’s most noticeable under braking. As soon as the brakes are applied and the load shifts the suspension moves and the nose dives.


Results – Dampers all 10
Feel – The car feels distinctly stiffer, particularly at the front end, changes in direction occur with almost no immediate roll felt. Trail braking in particular can be a bit disconcerting as when you begin braking the nose is steady and as you are turning into the corner it begins to roll. Over the rumble strips the car feels significantly stiffer and a lot less compliant, some of the higher curbs when taken at speed will also result in a slight loss of contact with the track.

Noise – Again mainly judged over the rumble strips, but is harsher in sound, and rather that the ‘soft’ sound of the previous test this is more of a ‘Tttrrrrrrrrrrrrrrrrrrraaappp’ sound.

Visual – Quite a marked difference from the previous test and quite clear if you straight-line brake, you can see the brakes go on and the laws of physics tell us that the load is being transferred, but at first we don’t see any movement from the front end of the car. The delay in the nose diving under braking can be clearly seen; the same can be observed with the rise of the nose (as the car squats back after acceleration). Even cornering and trail braking shows a slight delay in movement.


Conclusion
Well given the results of the two tests above I can only conclude that damper settings of 10 are indeed stiffer that settings of 1, no other part of the car was changed or adjusted in any way, yet the delay in movement can be seen and felt with the Caterham running dampers set to 10.

Not only can the delay be seen and felt, but it also looks and feels as if more resistance is present in the suspension system.

Combine these two factors with the increase in harshness in noise, with the higher values, as the car runs over the rumble strips and for me this can only point in one direction.

I ran these tests at least a dozen times and the results were consistent and while I would need to run it for other cars (and I will) it’s a very, very clear indicator that higher damper values are stiffer in GT4


Regards

Scaff

 

[Mt. Lynx]

I have now contucted the above test, using Scaffs guidelines, and here are the results:

I tried the 10 dampers first, for some reason.
Feel
I can´t say that it was a stiff setup, but the damping produced some problems for me, especially while trailbraking. Understeer was a real issue, simply because of the slow reaction of the dampers. As soon as the brakes were released though, turn in was sharp and nice (for this setup that is), and the overall handling was not as bad as I had expected. I tried straighline braking, but lost too much speed during a turn for it to be better than trailbraking as a whole.
Sidenote
The choice of track is most likely the reason for the not-so-bad handling. There are only three brakingpoints, and only four gearchanges, so a longer, faster track is preferable for this. Please consider for example Autumn Ring, wich should be efficient enough for this, for the same reasons as Motorland.

Noise
Considerable screeching while turning, and when encountering a rumblestrip, the sound makes me think of a machinegun model large.

Visual
I was right about the understeer. This dampersetup provides almost no initial turn in, and the slow motion of the dampers makes me turn the wheels very hard, thus all the screeching. It looks as if the weighttransfer kind of "stands" on the suspension for a second, before it dips. This is true both in straightline braking, and trailbraking.

Dampers set to 1
Feel
The feel is almost the same, but with a few distinct changes. I get a good turn in with this damping, but mid corner I suffer some understeer, probably because of the front weight. Once turned, the weighttransfer kind comes late. The dip is more initial than with 10 damping, but the the front weight doesn´t take it´s toll on the car until you lift of the brakes mid corner. I try straight line braking instead, and that is better for negotiating a turn with these dampers, but trailbraking is still faster. Other than during braking, the ride is smoother than the 10 setup.

Noise
Less screeching during cornering compared to 10 damping. Also the noice while going over rumblestrip is not as machinegun oriented now, the sound is too slow for that. If 10 makes a "bbbbrrrrrapppp-ppp-p", 1 makes for a "babadababadabadap", if you know what I mean. That highly indicates that the motion of the damper if set to 1, moves significantly faster over a rumblestrip, than if set to 10.

Visual
Once again I was right about the understeer. The initial turn in and the weighttransfer, are almost immediate, but the sudden dip and the forward motion of the car, while braking/tuning, makes for a lift off understeer. The suspension took care of rumblestrips really nice. A straighline brake test also showed the immediate dip of the front.

Conclusion
Long story short: 1 is softer, and 10 is stiffer! Everything conducted here points to that.

 

[sucahyo]

Interesting. Especially the "bbbbrrrrrapppp-ppp-p" (d10) vs "babadababadabadap" (d1) noise. Which I think show high frequency beating vs low frequency beating, frequent bouncing vs seldom bouncing, more tire up-down vs less tire up-down, faster suspension movement vs slow suspension movement.

More comment later.

 

[Scaff]

Interesting. Especially the "bbbbrrrrrapppp-ppp-p" (d10) vs "babadababadabadap" (d1) noise. Which I think show high frequency beating vs low frequency beating, frequent bouncing vs seldom bouncing, more tire up-down vs less tire up-down, faster suspension movement vs slow suspension movement.

More comment later.

Are these statements meant to match up? If so are you saying that 'frequent bouncing' goes with 'more tyre up and down' and that 'seldom bouncing' goes with 'less tyre up and down'?

Because if that is the case its wrong (or you need to clarify bouncing - is this the car or tyre - I suspect from how its written that you mean car). The faster the suspension is able to move, the better able to keep in contact and follow the track and imperfections, and the less likely the tyre is to loose contact with the road.

You see neither Team 666 or I used the words 'bounce' or 'bouncing' at all, so I'm rather confused (if you have not carried out the test) as to why you are using it at all? In fact I don't believe that either of us even mentioned any loss of tyre contact with the track at all.

Regards

Scaff

 

[Mt. Lynx]

Interesting. Especially the "bbbbrrrrrapppp-ppp-p" (d10) vs "babadababadabadap" (d1) noise. Which I think show high frequency beating vs low frequency beating, frequent bouncing vs seldom bouncing, more tire up-down vs less tire up-down, faster suspension movement vs slow suspension movement.

More comment later.

Well, my pick is that 10 can´t cope with the irregularities as good as 1. This is a grip issue, not a bounce issue. A rumblestrip has too many irregularities for any suspension to cope with, and they loose grip no matter what. It´s just a question of how often the tyre looses its grip. If the noice is "high-frequent", that means that the dampers hardly move up or down at all, they make the tyre ride on the crests of the rumblestrip. If the sound has a lower frequenzy, the dampers are able to rebound every once in a while, and thereby achieves a smoother, and grippier ride over the rumblestrip. Do I have to point out wich setting makes what?

 

[sucahyo]

I will try compile all caterham testing that done in this thread. And will make conclution from it. I will post it tomorrow.

About high frequency, I relate it with my test where high damper show more tire vibration. More vibration = higher sound frequency.

 

[Scaff]

OK I've just re-run the test with a different car and track, I ran a Range Stormer at Autumn Ring, the car was set up to the same principal as above.

So Ride height max, spring rates min, stabilisers min, 200 ballast all out the front and race tyres.

Dampers all set to 1
Feel - A very, very, very scary ride indeed. The suspension is almost totally uncontrolled, the slightest change in throttle, brakes or steering results in immediate and sudden roll. The car does not have much more than a hint of resistance in the suspension, with the uncontrolled roll almost imposable to deal with. Rumble strips feel soft when encountered.

Noise - Quite a soft, almost muted noise as you run the rumble strips.

Visual - The load transfer is so un-controlled that the very moment the throttle is release to begin braking the load is shifting, in fact its almost done by the time you even get to the brake pedal. The suspension looks to have almost no resistance at all.


Dampers all set to 10
Feel - While the set-up itself means that huge levels of load transfer and roll are inevitable the suspension at least now feels like its trying to control it. A significant increase in resistance can be felt within the system and you now get some breathing room between your input and the beginning of the load transfer. Rumble strips can be felt more clearly and with a harshness that was not present before.

Noise - Quite clearly a faster, harder and sharper sound, overall much harsher as you pass over the rumble strips.

Visual - The load transfer is now much more clearly controlled that with the dampers set to 1, the initial resistance to the shift in load can be quite clearly seen.


Conclusion
Well to be honest the results simply back up the previous test, as far as how the dampers react to the transfer of load under acceleration, braking and cornering (so dive, squat and roll) higher values quite clearly add more resistance to the suspension system. The only logical conclusion that can be drawn form that, is the higher the damper value the stiffer it is.

It should also be noted (and I thought I had included it earlier), that the straight-line braking test is very telling, because while we can't physically remove the stabilisers from the set-up, we can take advantage of the fact that they only work under roll. So the straight-line tests effectively remove them from the picture (no body roll - just dive).


Regards

Scaff

 

[sucahyo]

So according to this experiment, damper 1 feel more direct and instant, damper 10 feel more disconnected and delayed?

edit:
I try to make video to show the difference, but I think compression make it hard to know the difference, not as good as on TV. The most notable difference is still visual.

see if you can guess which is which:
damper A
damper B

 

[Scaff]

So according to this experiment, damper 1 feel more direct and instant, damper 10 feel more disconnected and delayed?

I would not personally use the words direct or disconnected, as I said above the lower values have less resistance to the load and the higher values have more resistance to load. Its quite clear to see and quite obvious in feel.

Matching these to the descriptions for stiffer and softer damper settings from Skip Barber quite clearly indicates that the lower the value the softer the damper and the higher the values the stiffer the value.

However I would ask why you are asking for our clarification? If you have carried out the test then why have you not written up your own findings? Team666 and I have given you a template to use, so give us your findings from each run.

edit:
I try to make video to show the difference, but I think compression make it hard to know the difference, not as good as on TV. The most notable difference is still visual.

I don't agree that he most noticeable difference is visual, you have to look at the whole range of information, feel in particular is an important factor here, with sound certainly helping as well.

see if you can guess which is which:
damper A
damper B

Not this bloody one again.

How many times do I have to tell you I'm not going to play these daft games, get it through your head, I do not believe that visual information alone is enough. On top of that, while the compression is not to bad, the camera angle is.

Why do you think I said....

When playing the replays back (which is important for the visual element here) as soon as it starts playing hit the ‘X’ button to get the ‘in-car view’ and then use ‘R1’ to switch to the low chase cam and then use ‘L1’ to get a reverse view. This gives a very clear view of the front suspension in action.

...because from the chase cam you can't see the entire tyre and wheel and half of the suspension is hidden. The videos also only show the car running over rumble strips, no straight line brake test (despite my write-up saying this was one of the clearest of the visual parts) and all from a rear chase cam.

Quite frankly suchayo, the videos do not give a clear enough view of the suspension and show only one piece of info (rumble strips) and you can't even see the tyre in contact with the road.

I'm very disappointed (but frankly not surprised) that you have taken this approach, rather than a write up and you own opinion, you have simply posted up a couple of videos that are quite honestly not very useful at all and just chosen to question the descriptive terms Tream666 and I have used.

Regards

Scaff

 

[sucahyo]

However I would ask why you are asking for our clarification? If you have carried out the test then why have you not written up your own findings? Team666 and I have given you a template to use, so give us your findings from each run.

I ask if it's ok if call it that way. I already do the same test and I think for damper 10 words delayed reaction, late response, and disconnected feel, slower load transfer fits. From braking test I can't decide wether suspension move slower or faster.

I test caterham too, and get visual and sound impression close to your result.

I use this Skip Barber quote as reference:
"A stiffer bump setting slows down the motion on its corner and 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."

delay = late = longer period of time.

because from the chase cam you can't see the entire tyre and wheel and half of the suspension is hidden. The videos also only show the car running over rumble strips, no straight line brake test (despite my write-up saying this was one of the clearest of the visual parts) and all from a rear chase cam.

That's what I think too. That's why I do another experiment seeing the car from track side camera (B-Spec mode).

I'm very disappointed (but frankly not surprised) that you have taken this approach, rather than a write up and you own opinion, you have simply posted up a couple of videos that are quite honestly not very useful at all and just chosen to question the descriptive terms Tream666 and I have used.

Just checking, wether it's worth to create video for it or not, it seems the answer is no. I also can't get satisfactory result when recording video, it seems the card can't capture fast tire movement we see in TV, I have interlacing problem and sound which is too much alike. So, I will post my test without video. But I can post it if needed, although it would need a bit time for me to upload (4 x 15MB).

My experiment result:


Viewing the car (tire) behaviour when driven in B-Spec Mode in Autumn Ring, default track camera mode. Pure visual test, but as the trackside camera zoom in the tire in some corner we can see tire get shaken up and down more clearly and how the tire loose contact with the road:

Test 1.

Fully tuned Subaru 360 (atleast with stage 3 weight mods, FC suspension) R5 tire, set A :
-Spring Rate: 1.5 / 1.4
-Ride Height: 216 / 216
-Bound: 10 / 10
-Rebound: 10 / 10
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 1 / 1

From track side camera I can see the tire shake up and down rapidly in some corner, mainly because rumble strip. But I can still see it when the car front get lift up by bump, where the front tire show a violent up and down movement. In the uphill 90 degree corner after the short tunnel, I can see the car loose traction because the tire shake too much, even without touching rumble strip, both front and rear tire. A simptom that indicate the damper is too soft to prevent the tire do high frequency vibration. This is the kind of tire vibration that I see on real car Hyundai Atoz GLS.


Fully tuned Subaru 360 (atleast with stage 3 weight mods, FC suspension) R5 tire, set B :
-Spring Rate: 1.5 / 1.4
-Ride Height: 216 / 216
-Bound: 1 / 1
-Rebound: 1 / 1
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 1 / 1

The car is more stable on rumble strip. The tire vibration is less and car get more stable on corner. The car have more control in 90 degree corner.



Test 2.
Fully tuned Caterham Fireblade (atleast with stage 3 weight mods, FC suspension) R5 tire, set A :
-Spring Rate: 5.0 / 3.8
-Ride Height: 90 / 90
-Bound: 10 / 10
-Rebound: 10 / 10
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 1 / 1

Same as Subaru 360, I can see tire vibration, but not as much. But still the car looks loose control when the tire shake badly.


Fully tuned Caterham Fireblade (atleast with stage 3 weight mods, FC suspension) R5 tire, set B :
-Spring Rate: 5.0 / 3.8
-Ride Height: 90 / 90
-Bound: 1 / 1
-Rebound: 1 / 1
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 1 / 1

More stable in corner and in rumble strip.


I also get the same result in Honda N360 and Citroen 2CV (no video).

Conclusion from test:
damper 10 will allow more or faster tire up and down movement, either when passing rumble strip, passing corner or when the front end or rear end is lifting.

If you think that this is visual error then you can check that this happen on many lightweight car. I even see the hint of this in F1 car (Formula Gran Turismo). I personally feel that this is not a visual error, but a correct simulation of loosing traction caused by tire shake up and down too much.

 

[Scaff]

I ask if it's ok if call it that way. I already do the same test and I think for damper 10 words delayed reaction, late response, and disconnected feel, slower load transfer fits. From braking test I can't decide wether suspension move slower or faster.

Delayed reaction and late response are fine ways of describing what is occurring (just not necessarily the words I would use), disconnected I would not use personally. Slower load transfer is just plain wrong, the load transfer is not slowed at all; the suspension reaction to the load transfer is slowed. As a result the load transfer itself happens over a shorter period and is more abrupt.

I have to say if you can’t see the difference between the speeds of suspension reaction in a straight line brake test then why do you rely on visual tests so much?

I test caterham too, and get visual and sound impression close to your result.

Good

I use this Skip Barber quote as reference:
"A stiffer bump setting slows down the motion on its corner and 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."

delay = late = longer period of time.

This all goes to show that you still have not fully understood how dampers work.

Stiffer dampers settings (as Skip Barber says) slow down the motion at a corner (or in the case of the straight line brake test – front end), this is the speed of suspension reaction that is being discussed here, not the contact patch. The delay in reaction of the suspension is what causes the load transfer to take place so suddenly.

The delay and late reaction we are talking about and can see/hear/feel in this test are quite clearly the resistance to the load transfer. The stiffer a damper is the more resistance to the load transfer it will have and the longer it will take to react, which will be shown as a delay in the movement of the suspension.

GT4 does not actually give us the tools to be able to directly see how the contact patch of the tyre loads and unloads, but the Caterham does allow us to see and feel the delay in suspension reaction to the load transfer (“slows down the motion” from Skip Barber) and this reduces the time available for the load transfer (“speeds up the load transfer” from Skip Barber). Soft dampers on the other hand have less resistance and as such will begin to react quickly (“allows the suspension to move faster” from Skip Barber) and as a result the load transfer itself starts sooner and therefore has more time to spread the load (“spread the changes in loading out over a longer period of time” from Skip Barber).

The Skip Barber quote quite clearly talks of firmer dampers resulting in slower suspension movement (from more resistance) and softer dampers resulting in quicker suspension reactions, the straight line test on the Caterham quite clearly show this at work. Higher damper values clearly show more resistance, slowing down the movement of the suspension, the feel of the front under braking is that of a clear increase in resistance over lower values. All of the above indicates that higher damper values are firmer.

You are either unable to understand the fundamentals of suspension and damper reactions to load, or you have realised you are wrong and are now scrabbling around for a route out and I can assure you this one is not it.

That's what I think too. That's why I do another experiment seeing the car from track side camera (B-Spec mode).

Why not use the reverse chase cam?
Why use B-spec? It removes feel from the test completely, so once again you are working with limited information.

My experiment result:
Viewing the car (tire) behaviour when driven in B-Spec Mode in Autumn Ring, default track camera mode. Pure visual test, but as the trackside camera zoom in the tire in some corner we can see tire get shaken up and down more clearly and how the tire loose contact with the road:
Conclusion from test:
damper 10 will allow more or faster tire up and down movement, either when passing rumble strip, passing corner or when the front end or rear end is lifting.

So now you are not only just looking at visual info only (no feel or sound), but you are only looking at a single aspect of this. How is this a well balanced test?

Well the answer is that it quite clearly isn’t. What you seem to be doing is focusing simply on the areas that you believe support your opinion, and anything else simply gets ignored. You test ignores the elements of feel and noise and focuses on a single point, ignoring anything else.

That said even this single point of focus is flawed, you are looking simply at the wheel/tyre rather than the suspension travel in relation to the car as a whole. Of course when you encounter a bump or series of bumps the tyre & wheel are going to travel over it (they can hardly go through it), the question is whether the suspension will move to absorb the bump or not. If it does then the suspension and tyre will rise and fall with the bump but the car will not, if the suspension is too stiff to react in time then the force will transfer through to the suspension to the car and the whole car will rise and fall with the tyre and wheel as it encounters the bump. Its for this reason that stiffer damper settings have a harsher feel and stiffer ride.

I've run this test with a wide range of cars and with higher values the feel and look of the car (body and suspension) is that of one that can't cope with bumps through the suspension alone, it can't react quickly enough.

However this is an area that visual GT4 does not do a great job on, which is why the other elements are vital to take into account here, feel and noise are critical here and you have simply ignored them.

If you think that this is visual error then you can check that this happen on many lightweight car. I even see the hint of this in F1 car (Formula Gran Turismo). I personally feel that this is not a visual error, but a correct simulation of loosing traction caused by tire shake up and down too much.

I have checked it out, with the two cars detailed above, also with a Subaru 360 and FGT, I plan to run it with more cars, but so far every car tested clearly indicates that higher damper values are firmer, this is looking at all forms of information.


Regards

Scaff

 

[Scaff]

In order to keep two damper related threads together I have asked for all future replies related to the following thread....

https://www.gtplanet.net/forum/showthread.php?p=2524575&posted=1#post2524575

..to be posted here.

I have not merged the two threads together on the ground that a lot of posts are by similar members to this one, and as they ran parallel the end result of a merge would be very confusing indeed. Rather I would suggest reading the last few pages of the thread linked to above.

Regards

Scaff

 

[sucahyo]

Famine,

damper bound = a state when damper compressing, when tire and/or car body squeezing the damper.
damper rebound = a state when damper expanding, when tire and/or car body pulling the damper.

By design, car damper rebound friction usually made higher than bound friction.

I will post other answer tomorrow.

 

[sucahyo]

GT4 does not actually give us the tools to be able to directly see how the contact patch of the tyre loads and unloads, but the Caterham does allow us to see and feel the delay in suspension reaction to the load transfer (“slows down the motion” from Skip Barber) and this reduces the time available for the load transfer (“speeds up the load transfer” from Skip Barber). Soft dampers on the other hand have less resistance and as such will begin to react quickly (“allows the suspension to move faster” from Skip Barber) and as a result the load transfer itself starts sooner and therefore has more time to spread the load (“spread the changes in loading out over a longer period of time” from Skip Barber).

Confusing.

What confuse me:
- stiffer damper work that way? stiffer damper have longer reaction time? Make suspension stop for a moment longer? I thought either soft or stiff both will work right away.
- when the car react quickly to braking, isn't it will have sooner/faster load transfer and loose tire traction sooner too?
- If we put two GT4 Storm with different damper side by side, which car screetching the tire first when braking, late reaction or quick reaction? Since I think car which smoke the tire first has faster load transfer.


How it relate to this:

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.

If I mix both your opinion about very stiff damper:
- when braking the suspension is unable to react quickly enough and send the force to the car and make it ............., I don't know what car reaction is.
- when meeting bump very stiff damper will delay car's reaction a moment longer.

Both do not make any sense.



About B-Spec Subaru 360 experiment:
I want to see the vibration more clearly. My previous test in Caterham only show the difference of tiny vibration, which need to be observe before we can notice it. I need to see how GT4 make the tire vibrate. It seems we can see tire vibration if:
- the car is lightweight
- has high ride height
- has soft spring rate
- there is bump in track

I use Subaru 360 at first. Since B-Spec mode has side track camera, I use it to see when it's tire vibrate. The tire vibrate on this event:
- passing rumble strip
- passing grass or dirt
- when car end is lifting
- passing bump

Car can loose traction after the tire vibrate much, most noticable on 90 degree corner after tunnel in Autumn Ring.



Initially I want to see the relation between sound and visual, do the sound matches with visual or not. See if GT4 show some visual and sound inconsistency. I plan to do the same with feel. Since I only got DS2, I plan to see what event that can make the DS2 vibrate, and then plan to test the connection between tire vibration and DS2 vibration.

I use -50 balast Caterham at first, but since it make the rear jump around at rumble strip I change balast to +50. Car speed is from memory, maybe wrong.
At 10mph the tire follow the rumble strip shape nicely, the sound is synchronize with visual.
At 20 mph the tire have a bit difficulty to follow rumble strip shape, the movement of the tire become a bit different when using different damper. The tire sound still consistent.
At 30 mph the tire have more difficulty to follow rumble strip shape. When using high damper value, the tire move around too much and give occational jump. When using low damper value the car more stable, with tire do not try to follow rumble strip shape as much as when using high damper value. tire sound still consistent.
As I travel over rumble strip faster, the tire sound frequency increase.

At this stage I make conclution that tire visual and sound is consistent. The faster we travel over bump the higher the tire sound frequency. if we hear a beat then the tire hit something.

Once again you have brought into play factors that I have no experience of, can I please be provided with before and after videos and pictures of both you dads car and your bike? If not stop using them as examples, they are totally unquantifiable to anyone and you can’t prove a damn thing about them one way or the other. I’ve asked you to prove that a ‘stiffer’ damper was indeed fitted to your dad’s car, rather than simply a replacement of a fault damper and you have not even managed to do that.

Notice that I don't post this in damper thread, I only use this to explain why I have stubborn opinion about GT4 damper is reversed. This is my real life experience, if you don't believe me, fine. I will try to not to talk about this in GT4 damper thread.

Do you really have no experience seeing or driving car with damper so soft that suspension shaking and make a lot of noise on sucessive small bump?

In the last Caterham test you freely admit that higher damper values increase the resistance within the suspension system, this is a clear indicator that higher values are stiffer

No, different conclution. I have the same result, but conclude it different way, see my previous post in damper thread where I try to explain why I have different conclution.



About not answering many post, sorry to everyone, I have no intention to disrespect anyone.



Dave_George, thank you. Ok, stiffer damper is firmer, send more bump shock to our body. How about vibration and sound? Do the suspension make more busy sound or make more vibration? Do the tire vibrate more when firmer? Since I think the harsh sound we hear in GT4 come from the tire. If you say yes I will stop arguing.

If there is vibration please tell if it still carry on even after passing bump or road irregularity.

BTW, what event can make DS2 controller vibrate? is it from this?:
- tire loose grip
- tire vibrate
- tire hit something
- landing from jump
- car hit something
- tire traveling the rumble strip
- tire out of track
- tire passing bump in track

Are you sure that the vibration you feel in DS2 is the result of more force send to the car body? Where do you feel it? when braking or hitting single bump?

 

[Mt. Lynx]

Dave_George, thank you. Ok, stiffer damper is firmer, send more bump shock to our body. How about vibration and sound? Do the suspension make more busy sound or make more vibration? Do the tire vibrate more when firmer? Since I think the harsh sound we hear in GT4 come from the tire. If you say yes I will stop arguing.

Ok, stop arguing! YES the tire (or the wheel, to be more precise) will vibrate more on a stiffer damper! The wheel will occillate more if the damping is softer though. Maybe you are referring occilation as vibration? In that case, case closed!

 

[Famine]

Famine,

damper bound = a state when damper compressing, when tire and/or car body squeezing the damper.
damper rebound = a state when damper expanding, when tire and/or car body pulling the damper.

By design, car damper rebound friction usually made higher than bound friction.

And when you say "stiffer damper" are you referring to the bound side or the rebound side?

 

[Scaff]

Confusing.

What confuse me:

OK sucahyo it’s quite clear that you have some major shortfalls in your knowledge and understanding of dampers and load transfer here.

Lets take these points one at a time

Q. stiffer damper work that way? stiffer damper have longer reaction time? Make suspension stop for a moment longer? I thought either soft or stiff both will work right away.

A.Yes dampers do work in this way. The stiffer the damper the more force is required to compress it. As suspension movement does not happen immediately, until the force required to compress (or rebound) the damper has been reached it will resist the force.

Take a look at the diagram below; the red trace represents a damper with a stiffer shim stack than the blue trace. At a shaft velocity of 3 inches/second the soft damper (blue) requires approx 180lbs of force to compress/rebound, while the stiffer damper (red) requires approx 210lbs of force to compress/rebound.

Now as the stiffer damper will resist compression/rebound until the greater load is placed upon it this will delay the reaction of the suspension. However as the total load transfer will take a fixed amount of time, the longer the delay, the less time a stiffer damper has to load/unload the tyres contact patch and the quicker that load/unload will occur. The following figures are illustrative but may help, say it takes 1 second to full transfer a load of ‘Xlbs’, but 0.2 second to transfer our 180lbs (blue – softer damper trace) and 0.4 seconds to transfer our 210lbs (red – stiffer damper trace). This would result in the actual tyre load/unload occurring over 0.8 seconds for the softer damper but 0.6 seconds for the stiffer damper. So for the stiffer damper the time taken for the suspension to react is 0.4 seconds (so longer than the soft damper) but the load itself was transferred in a shorter time of 0.6 seconds.

Now the above is a very, very simple look at how this works (its actually not 100% accurate either as load transfer is occurring ‘through’ the damper when its not reacting – but it does help ‘visualise&#8217, but an understanding of these basics is a must. I simply fail to see how you can claim to ‘know’ that damper values in GT4 are reversed while being unaware of the fundamentals of how dampers operate.

So to answer you questions, no soft and firm damper will not both react straightaway. This is why on the straight-line brake test for the Caterham the delay in movement (visual) and increased resistance to load (feel and visual) are both very clear indicators that higher GT4 damper values are stiffer.

The reaction in the Caterham is easy to see and feel because set to 10 it is over-damped for the weight of the car and load.


Q. when the car react quickly to braking, isn't it will have sooner/faster load transfer and loose tire traction sooner too?
A.No, damper settings do not alter the total load transfer, just (in general terms) the speed at which it is transferred. However as tyres are load sensitive, delays in transferring load may reduce the grip available to brake, accelerate, etc.

Strictly speaking if the tyres are going to be overloaded its going to happen regardless of the damper setting, however with the loading/unloading of the contact patch spread out over a longer period of time with the softer damper this may well feel more progressive and the driver may have more time to react and control it. The shorter period of time offered by the quicker load/unload of the stiffer damper can make it much more abrupt and gives less time to react. However the amount of load here has not fundamentally changed.



Q. - If we put two GT4 Storm with different damper side by side, which car screetching the tire first when braking, late reaction or quick reaction? Since I think car which smoke the tire first has faster load transfer.
A. I very much doubt that you could see a major difference in GT4 by looking at this. Two main reasons why, the first being that in straight-line braking it’s simply not possible to lock the tyres fully, the ABS cuts in first. Secondly a loss of grip under braking is caused by the tyres exceeding there slip percentage (difference in tyre rotational speed to vehicle speed measured as a percentage), the exact slip percentage available under braking is determined by the traction available to the tyre. In very simple terms this is determined by the Cf of the tyre and the working on it. Too little load and you will not make full use of the potential grip and not brake effectively. Too much load and you can overload the fronts and exceed the slip percentage, in the real world locking the tyres or triggering the cars ABS (GT4 only gives the ABS option).

It’s not a realistic option for testing in either the real world or GT4.

The Caterham test was more than complete enough In all these areas and simply put the additional resistance to the load transfer with higher damper values, in the straight-line braking test is more than enough to show that higher damper values are stiffer.

One thing does slightly bother me, that’s not the first time I have used that quote from Skip Barber and you have in the past claimed to be quite happy with it and understand it. Yet the questions you have asked above clearly show that was not the case. However for the sake of completion lets look at it one more time, knowing that we all agree that higher damper values slow down the Caterham’s suspension movement under straight line braking.

A stiffer bump setting slows down the motion on its corner and 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 the two parts I have highlighted in bold quite clearly say that stiffer settings will
“slow(s) down motion on a corner” and “force the suspension to move more slowly”. I don’t personally see how it could get any clearer, the piece is without any doubt saying that stiffer damper settings will slow down the suspension movement, and with higher damper values in GT4 that’s exactly what happens.

How it relate to this:
If I mix both your opinion about very stiff damper:
- when braking the suspension is unable to react quickly enough and send the force to the car and make it ............., I don't know what car reaction is.
- when meeting bump very stiff damper will delay car's reaction a moment longer.

Both do not make any sense.

Sucahyo please show me exactly were I said “when meeting bump very stiff damper will delay car's reaction a moment longer”, because I do not believe I said that at all. I said that the suspension would not be able to react quickly enough and transfer the force to the car. I have made not mention of the car’s reaction being delayed?

Any confusion here is your own and if it doesn’t make sense then I would suggest that you have not grasped the fundamentals of dampers.

About B-Spec Subaru 360 experiment:
I want to see the vibration more clearly. My previous test in Caterham only show the difference of tiny vibration, which need to be observe before we can notice it. I need to see how GT4 make the tire vibrate. It seems we can see tire vibration if:
- the car is lightweight
- has high ride height
- has soft spring rate
- there is bump in track

I use Subaru 360 at first. Since B-Spec mode has side track camera, I use it to see when it's tire vibrate. The tire vibrate on this event:
- passing rumble strip
- passing grass or dirt
- when car end is lifting
- passing bump

Car can loose traction after the tire vibrate much, most noticable on 90 degree corner after tunnel in Autumn Ring.

Why are you deliberately ignoring the Caterham test? The straight line braking reaction in that test seems to have got you out of sorts, it’s the only reason I can think that you are avoiding it. The above tests are a part of the whole mix, but I don’t understand your obsession with running tests in B-spec mode. Why not drive yourself? That way you could incorporate feel into this and actually have some complete feedback, rather than sucahyo-friendly highlights.

Initially I want to see the relation between sound and visual, do the sound matches with visual or not. See if GT4 show some visual and sound inconsistency. I plan to do the same with feel. Since I only got DS2, I plan to see what event that can make the DS2 vibrate, and then plan to test the connection between tire vibration and DS2 vibration.

Since when have you been using a DS2? In the past every mention has been of a digital only third party pad.

At this stage I make conclution that tire visual and sound is consistent. The faster we travel over bump the higher the tire sound frequency. if we hear a beat then the tire hit something.

Great and that proves what that’s new. Oh that’s right, not a damn thing.

Do you really have no experience seeing or driving car with damper so soft that suspension shaking and make a lot of noise on sucessive small bump?

Prove what you are talking about here has anything to do with dampers.

Small regular bumps passed at speed are normally a factor of high frequency ride issues and dealt with by bushings rather than dampers.

I strongly suspect I have a lot more experience of driving differing vehicles, with differing set-ups and on a range of terrain that you do.

No, different conclution. I have the same result, but conclude it different way, see my previous post in damper thread where I try to explain why I have different conclution.

You may have a different conclusion, but lets be quite straight about this, given the information available it’s the wrong conclusion. Everything about these tests, the previous tests, and every person who has tested this comes to the same result. Higher damper values are stiffer, the only person who has a different conclusion on this is you.

I’m going to be very, very blunt on this one.

Sucahyo you are wrong. Higher GT4 damper values are stiffer; you have totally failed to present a valid test or a reasoned argument to prove otherwise (and lets be fair you've had almost a year to do so).

Why are you persisting?

Regards

Scaff

 

[sucahyo]

Ok, stop arguing! YES the tire (or the wheel, to be more precise) will vibrate more on a stiffer damper! The wheel will occillate more if the damping is softer though. Maybe you are referring occilation as vibration? In that case, case closed!

I am not asking about GT4 damper Team666, I am asking Dave_George about his real life Koni adjustable damper.

And when you say "stiffer damper" are you referring to the bound side or the rebound side?

Both.




Scaff, I would understand better if you use damper reaction graph (suspension movement vs time). What I have look like this:


This graph show that even on stiff damper, the suspension still move (case C). Stiffer damper slowing down the suspension movement more than soft damper.

I never see time graph that fit with your description of delayed damper reaction.


"The stiffer the damper the more force is required to compress it" is misleading. The correct word whould be stiffer damper absorb more force. At a shaft velocity of 3 inches/second the soft damper (blue) absorb approx 180lbs of force when compress/rebound, while the stiffer damper (red) absorb approx 210lbs of force when compress/rebound. Those absorbed force will be send to the car body.

When the car suspension got compressed by bump, the damper will try to absorb the force and spring rate will try to resist the force. Car body will receive force that being absorbed by damper and resisted by spring. So when a BTCC alfa do cornering and the car body try to roll, stiffer damper or stiffer spring can increase roll when the inside tire meeting bump. And when the tire drop the the road again, stiffer damper will prevent spring from storing much of downward energy and prevent it to bounce.


I don't ignore Caterham test, I don't mentioned because when our basic understanding different our conclution will be diferent too. So I intent to discuss the basic first.


The way I translate Skip Barber quote:
Stiffer damper will slowed down suspension movement more, ie. stiffer damper will reduce the suspension movement faster. If stiff and soft damper have to stop the shaft movement that has speed of 3 inches/second, at 1 second later stiff damper can slow it down to 1 inches/second, where softer damper only slow it down to 2 inches/second.

Because suspension movement got stopped faster, the load transfer happen faster too, making more abrupt load transfer.


Scaff, can you explain how damper work when receiving single direction movement (bump) without spring equipped? use this image bellow as reference:

What happen when the tire receive bump, second by second until right before the suspension bottomed out, with the assumption that the k1 and k2 is null. How the speed change, what is the difference between stiff and soft damper, how much force recieved by the car, how much force is lost, how much different the damper will react on different bump speed, etc.


From what you describe before this is my conclusion:
- You think that damper will stop the suspension from movement until the force it receive fulfill the treshold and make suspension move again. soft damper and stiff damper have different reaction time. Using this if the initial shaft speed is 3 inches/second then:
soft damper: shaft will be move again after 1 second, what happen after moving and before bottoming out is not explained.
stiff damper: shaft will be move again after 2 second, what happen after moving and before bottoming out is not explained.

- You think that damper will be unable to react fast enough on fast bump and send force directly to car body. How fast is fast is not explained. What happen when the damper is half fast enough is not explained. Using this suspension do not move at all.

 

[Scaff]

Scaff, I would understand better if you use damper reaction graph (suspension movement vs time). What I have look like this:


This graph show that even on stiff damper, the suspension still move (case C). Stiffer damper slowing down the suspension movement more than soft damper.

Well done suchayo, now lets take a quick look at that diagram you posted and with a ‘right-click’ and view the link properties we can go and have a look at the original document.

What do we find, well it’s a document entitled “Basics of Structural Vibration, Testing and Analysis”, that’s right it’s a document on the use of damping in buildings, most commonly tall structures such as skyscrapers. The exact graph you show is for a mass-damper unit in a building, which looks commonly like this:

And here is a link to the full document, so every one can have a look
http://www.lds-group.com/docs/site_documents/App 11.pdf


Now that’s hardly a like for like example to use when discussing automotive dampers, which while sharing similar qualities do not work in exactly the same way, nor serve the same purpose as mass dampers used in buildings.

I’m sorry but this really is a rather sad state of affairs, what the hell are you doing using this as an example!

I never see time graph that fit with your description of delayed damper reaction.

Maybe because you appear to be using ones that are related to the damping of harmonic vibrations in tall buildings!

"The stiffer the damper the more force is required to compress it" is misleading. The correct word whould be stiffer damper absorb more force. At a shaft velocity of 3 inches/second the soft damper (blue) absorb approx 180lbs of force when compress/rebound, while the stiffer damper (red) absorb approx 210lbs of force when compress/rebound. Those absorbed force will be send to the car body.

And what mechanism is used to absorb that force? That’s right the compression of the damper itself. Suchayo for someone who has just tried to present a diagram illustrating buildings mass damper as a vehicle damper you really should not then try and make issue of a single word.

Your use of building mass-dampers is quite simply one of the most misleading things I have seen in a long time. First off if I ever find out you knew that was a document about a building damping system I will issue an immediate infraction (posting knowingly misleading info is an AUP violation). If however you did not realise it then its gets just as concerning, as it means you read that document and picked the diagram without realising it was discussing building damping. Which ever option does not look good for you.

What makes it even worse is that on a very basic level it even helps to prove my point. The over-damped line even shows that the ‘mass-damper’ is slower to react physically (i.e. move) that the correctly damped and under-damped lines. Both of which have near vertical movement lines within very short time windows, the only one with a visible delay to the movement is the over-damped line, which is quite clearly shallower.

So not only does the graph help illustrate exactly what I have been saying, but you are know either incapable of distinguishing between building and automotive dampers or trying to deliberately miss-lead. I would like an explanation behind this, and believe me it better be good.

When the car suspension got compressed by bump, the damper will try to absorb the force and spring rate will try to resist the force. Car body will receive force that being absorbed by damper and resisted by spring. So when a BTCC alfa do cornering and the car body try to roll, stiffer damper or stiffer spring can increase roll when the inside tire meeting bump. And when the tire drop the the road again, stiffer damper will prevent spring from storing much of downward energy and prevent it to bounce.

Uhh well done, once again this does not make a great deal of sense. What exactly are you trying to say here? Because at first glance it looks a lot like you are trying to say that stiffer dampers and springs will cause more body roll?

I don't ignore Caterham test, I don't mentioned because when our basic understanding different our conclution will be diferent too. So I intent to discuss the basic first.

Yes you have ignored the Caterham test, the second I pointed out that your own observations indicated that higher values = stiffer dampers you have avoided it as much as possible.

As far as understanding the basics go, it seems to me that you have spent the best part of a year avoiding doing just that.

The way I translate Skip Barber quote:
Stiffer damper will slowed down suspension movement more, ie. stiffer damper will reduce the suspension movement faster. If stiff and soft damper have to stop the shaft movement that has speed of 3 inches/second, at 1 second later stiff damper can slow it down to 1 inches/second, where softer damper only slow it down to 2 inches/second.

Because suspension movement got stopped faster, the load transfer happen faster too, making more abrupt load transfer.

What!!!!!!

The Skip Barber quote does not require any translation and this strikes me as you once again attempting to avoid the rather straightforward issue here. What the quote quite clearly says (and this is not ambiguous at all) is that stiffer damper will react more slowly (in terms of physical movement) to load. This is repeated over a number of different quotes and from a range of sources I have supplied. Not only that but common sense applies here as well, a ‘firmer’ rated damper will put more resistance in the suspension system (as it’s now set-up to resist the springs more).

The Caterham example clearly illustrates this, and now you appear to be trying to ‘re-word’ this quote to suit your explanation of events. Let me give you a quick clue here, if you are having to reword everything to make it ‘fit’ your conclusion (and that’s exactly what you are doing), then it’s a fairly good chance you are wrong.

Scaff, can you explain how damper work when receiving single direction movement (bump) without spring equipped? use this image bellow as reference:

What happen when the tire receive bump, second by second until right before the suspension bottomed out, with the assumption that the k1 and k2 is null. How the speed change, what is the difference between stiff and soft damper, how much force recieved by the car, how much force is lost, how much different the damper will react on different bump speed, etc.

You would like me to explain how a car would react to a bump if the springs were removed and the tyres were solid? I’m not entirely sure why or what this will achieve, but OK.

As dampers do not support any weight at all, were you to remove the springs from the suspension system the car would immediately start to sink. The sprung mass of the car would put the un-sprung dampers into bound, the sprung mass compressing them.

How long this would take would depend on the damper rating and the sprung mass, but assuming a road car it would be inevitable. The car would sink onto the dampers bump-stops and best of all I used to own car you could do this to. The Citroen BX was one many Citroen models fitted with Hydropneumatic Suspension, in which the springs are replaced by a pressurised pneumatic system. As this was pressurised fully by the engine, when you turned the car off the system would slowly bleed, reducing the effective spring rate as it did. Now this was done in a very slow manner, but come back to the car after it was parked all night and it would be settled on its stops. You had to run the engine for a minute or so to re-pressurise the system and as it did so you could watch the car rise.

The end result is that removing the springs from the system will actually give you whatever effective ‘spring rate’ the bump-stops will provide, which is almost certainly going to be quite firm.

As to what would happen on encountering a bump, well most likely the ride would be rather uncomfortable and the force would be transferred almost immediately to the sprung mass, as without the springs the dampers have nothing to actually damp.

From what you describe before this is my conclusion:
- You think that damper will stop the suspension from movement until the force it receive fulfill the treshold and make suspension move again. soft damper and stiff damper have different reaction time. Using this if the initial shaft speed is 3 inches/second then:
soft damper: shaft will be move again after 1 second, what happen after moving and before bottoming out is not explained.
stiff damper: shaft will be move again after 2 second, what happen after moving and before bottoming out is not explained.

No I did not say that, once again you are not actually reading what I have actually written, simply what you want to read. Did you miss this part?

Now the above is a very, very simple look at how this works (its actually not 100% accurate either as load transfer is occurring ‘through’ the damper when its not reacting – but it does help ‘visualise’), but an understanding of these basics is a must. I simply fail to see how you can claim to ‘know’ that damper values in GT4 are reversed while being unaware of the fundamentals of how dampers operate.

- You think that damper will be unable to react fast enough on fast bump and send force directly to car body. How fast is fast is not explained. What happen when the damper is half fast enough is not explained. Using this suspension do not move at all.

And given the number of variables involved you want me to explain every possible situation to you. Sorry sucahyo but this is simply you getting off the topic once again in an attempt to avoid the rather straightforward points I have raised. So here we go again.

• You have failed to provide any test that clearly and repeatedly shows that GT4 damper values are reversed.
  
• Numerous tests have been provided (by a wide range of people) and repeated that show that GT4 damper values are not reversed.
  
• You have posted misleading, incorrect and non-sourced info repeatedly to attempt to get around the above two.
  
• You have constantly failed to demonstrate an understanding of real-world damper knowledge.
  
• You repeatedly miss-quote or ‘put words in people’s mouths’ in an attempt to get around the first two points above.
  
• You have failed to put your GT4 tuning theory into practice on a regular basis, simply put independent drivers don’t agree with you.
  
• You have come close to violating the AUP on a huge number of occasions, the latest being today.

The burden of proof here is with you, I have yet to meet one single person here at GT Planet who actually accepts your GT4 Dampers are reversed theory. As such the onus is on you to prove this and as I have said in the course of a year you have failed to do this.

 

[sucahyo]

Your use of building mass-dampers is quite simply one of the most misleading things I have seen in a long time. First off if I ever find out you knew that was a document about a building damping system I will issue an immediate infraction (posting knowingly misleading info is an AUP violation). If however you did not realise it then its gets just as concerning, as it means you read that document and picked the diagram without realising it was discussing building damping. Which ever option does not look good for you.

I realize that the article talk about building damper, but I believe it work the same way as car damper. And I think those graph represent what I want to talk more clearly. I have other graph which show the same trend:


This graph still show that damper will react at the same time no matter what it's stiffness is.

And what mechanism is used to absorb that force? That’s right the compression of the damper itself. Suchayo for someone who has just tried to present a diagram illustrating buildings mass damper as a vehicle damper you really should not then try and make issue of a single word.

I think I need to explain how damper work in a more basic way. I will use this to explain the way I translate Skip Barber quote.

How fluid in damper create resistance, using needle as example.
some graph from minimania SUSPENSION - Shock absorbers (dampers), basic knowledge
I don't know what this thing called exactly but I will refer it as needle:


First, how come needle can be used to simulate damper behaviour?

Let us look how damper internal look like:




And then read how damper contructed:
- Right, so the basics of how a damper works is a piston/valve moving up and down in an oil bath. The oil affords a certain amount of resistance, the varied complexities of control dealt with by the design of the valving (how much oil it lets past and when).
- All hydraulic shock absorbers work by the principle of converting kinetic energy (movement) into thermic energy (heat). For that purpose, fluid in the shock absorber is forced to flow through restricted outlets and valve systems, thus generating hydraulic resistance. A telescopic shocka bsorber (damper) can be compressed and extended; the so called bump stroke and rebound stroke.
- There is a piston attached to the end of the shaft inside the damper. The chamber that the piston moves in is filled with (almost) incompressible hydraulic oil. The viscosity of the oil causes resistance to oil passage through small orifices. This resistance produces a pressure differential across the piston when the piston moves, thus producing a damping force.

Needle has a piston that force water through small output hole, creating resistance. With this we can simulate what happen on damper bound state. If you want to simulate rebound state too, put the needle under water. If you find this stupid Scaff, try explaining how damper word in your own word, without quoting some else word, using analogies like this if you can.

For this experiment I use needle with detachable pipe.
First, I remove the detachable pipe, I hold the needle like this:


Then I press the needle up to half:


Now imagine that thumb finger represent wheel, and other finger represent car body, in the same way we imagine tire attached to one end of the damper and car body hold the other end of the damper.

The experiment result:
- When you move the needle piston faster you got more resistance, simulating damper velocity sensitive property.
- When you press your thumb harder (faster), the other finger will receive more pressure too, simulating how car body receive more force when damper absorb more force.
- When you press your thumb quickly you got slowed down, simulating damper behaviour slowing down suspension movement.


Next I equip the needle with small pipe, simulating stiffer damper:


Then I press the needle up to half:



The experiment result:
- At relatively the same pressure, the piston move much more slowly, simulating stiffer damper slowing down suspension movement at the same force.
- Trying to get the same piston speed as first experiment would need a much greater pressure, simulating stiffer damper has more resistance at the same shaft velocity. The pressure received by other hand also stronger, simulating stiffer damper send more force to the car body.
- When you press your thumb quickly you got slowed down much more then previous experiment, simulating stiffer damper behaviour slowing down suspension movement more.
- No sign of needle piston prevent me to move my hand, it resist but still move a little, all it does is slowing down my thumb presssure speed. simulating that on any stiffness, damper react right away, either it move or stop moving. No "stop a second and then move" behaviour.

What makes it even worse is that on a very basic level it even helps to prove my point. The over-damped line even shows that the ‘mass-damper’ is slower to react physically (i.e. move) that the correctly damped and under-damped lines. Both of which have near vertical movement lines within very short time windows, the only one with a visible delay to the movement is the over-damped line, which is quite clearly shallower.

Notice the distance travelled by softer damper at the same time. At the same time softer damper travelled longer distance than stiffer damper. At the same x axis value, softer damper already travel more y axis value.

And the delay you are talking about is not like that, you are talking suspension waiting the force to reach certain value before it move, where the graph show both move right away. I see that you have difficulty of reading graph, I try to avoid using graph later. It seem that you don't know how the graph difference of late reaction and imidiate reaction. The graph show that all damper speed decrease over time. Faster initially and then reduced later. When the time vs movement graph show steep hill at first and flat hill later it means the speed is reducing.

Uhh well done, once again this does not make a great deal of sense. What exactly are you trying to say here? Because at first glance it looks a lot like you are trying to say that stiffer dampers and springs will cause more body roll?

Stiffer dampers and springs will cause more body roll:
- when the inside tire hit bump, yes
- When the inside tire do not hit any bump, no, the opposite.

Yes you have ignored the Caterham test, the second I pointed out that your own observations indicated that higher values = stiffer dampers you have avoided it as much as possible.

There is no use talking about that when our understanding about damper is different. I already mention in my old post that caterham behaviour happen because higher damper is softer.

As dampers do not support any weight at all, were you to remove the springs from the suspension system the car would immediately start to sink. The sprung mass of the car would put the un-sprung dampers into bound, the sprung mass compressing them.

...

The end result is that removing the springs from the system will actually give you whatever effective ‘spring rate’ the bump-stops will provide, which is almost certainly going to be quite firm.

not neccesarily on car. What a stationary damper (one end attached to solid object) do when it receive force. Don't answer it just by "it sink", answer it more descriptive please. Answer how damper react, and also what is the difference between stiff and soft. Is it too hard for you to explain the sink difference between soft and stiff, which one reach bump stop faster, what happen to the force when soft or when stiff?

As to what would happen on encountering a bump, well most likely the ride would be rather uncomfortable and the force would be transferred almost immediately to the sprung mass, as without the springs the dampers have nothing to actually damp.

Again, you do not differenciate soft damper and stiff damper.

No I did not say that, once again you are not actually reading what I have actually written, simply what you want to read. Did you miss this part?

Simply because your explanation is too inadequate that I have to do a lot of guessing. many question still not answered. What you use to explain some real life or GT4 behaviour can't be use to explain other behaviour.






If all of this answer still not understand then there is no point if I argue anymore. I guess the final result is I am the only one in the world who think GT4 damper is reversed.

 

[Scaff]

I realize that the article talk about building damper, but I believe it work the same way as car damper. And I think those graph represent what I want to talk more clearly. I have other graph which show the same trend:


This graph still show that damper will react at the same time no matter what it's stiffness is.

So you fully acknowledge that you have used a diagram representing mass-dampers in buildings and presented it as an illustration of automotive damper reactions (and done so numerous times), yet not felt the need to let anyone know that it did not represent automotive dampers.

When you used in within this discussion you clearly used the term “suspension movement” twice in reference to the diagram, a diagram which has nothing to do with suspension movement in the automotive sense. Do you not see just how misleading this appears?

I’m also going to take rather a large issue in this post to you once again attempting to make it appear that I have said something that I have not. I have maintained (and quoted from a number of sources) that stiffer dampers slow down suspension reaction, something that the diagram does clearly show and you admit clearly shows.

The terms delay and late reaction were first used by you:

I ask if it's ok if call it that way. I already do the same test and I think for damper 10 words delayed reaction, late response, and disconnected feel, slower load transfer fits. From braking test I can't decide wether suspension move slower or faster.

In the very next post I clearly said these were terms I would not personally use:

Delayed reaction and late response are fine ways of describing what is occurring (just not necessarily the words I would use)

I have no issue with them as descriptive terms, but as I quite clearly say, they are not terms I would ideally use myself, so please stop trying to make out that they are my preferred method of description or that they originated with me. You are the source of these terms, so if you have an issue with them, then you have yourself to blame. Go back and actually read my posts, the single dominant word I use to describe the effect of stiffer dampers on suspension movement is ‘slowed’, I don’t have a major issue with delayed or late response, but I have not said that no movement will occur at all or that movement will be stopped for a long period of time (although for hideously stiff and restrictive on a very light car it is theoretically possible).

Just as Allan Staniforth says here:

One very big advantage of a damper that can be altered separately on bump is that it can be used as an anti-dive or anti-squat device. This is because for a very short interval after loads are fed into the suspension, the car 'feels' a hard damper as almost solid.

Which is exactly what we see and feel in the Caterham with dampers set to 10, in the straight line brake test, the dampers acting as an anti-dive device.

I think I need to explain how damper work in a more basic way. I will use this to explain the way I translate Skip Barber quote.

***SNIP***

The experiment result:
- At relatively the same pressure, the piston move much more slowly, simulating stiffer damper slowing down suspension movement at the same force.
- Trying to get the same piston speed as first experiment would need a much greater pressure, simulating stiffer damper has more resistance at the same shaft velocity. The pressure received by other hand also stronger, simulating stiffer damper send more force to the car body.
- When you press your thumb quickly you got slowed down much more then previous experiment, simulating stiffer damper behaviour slowing down suspension movement more.
- No sign of needle piston prevent me to move my hand, it resist but still move a little, all it does is slowing down my thumb presssure speed. simulating that on any stiffness, damper react right away, either it move or stop moving. No "stop a second and then move" behaviour.

Good work on the explination and write-up, the slight problem is that not only do I not (on a basic level) dispute it, but it also supports exactly what I have been saying.

Stiffer dampers slow down or delay (take you pick in descriptive terms) the reaction of the suspension, I’ve said this from day one, and by contrast softer dampers allows the suspension to move more quickly, which is why they are better suited to bumpier surfaces. Go back and have a read of the first 10 or so posts in this thread, this is exactly what I have been saying since day one and exactly what you disputed.

I have not said that stiff dampers do not move at all (it is however quite possible that they could be restrictive enough that they show little or no visible movement. Yes I did give a very, very basic example which may have caused some confusion, but I did caveat that with the following (which you appear to be deliberately ignoring as I’ve already answered this question once before)

Now the above is a very, very simple look at how this works (its actually not 100% accurate either as load transfer is occurring ‘through’ the damper when its not reacting – but it does help ‘visualise&#8217, but an understanding of these basics is a must. I simply fail to see how you can claim to ‘know’ that damper values in GT4 are reversed while being unaware of the fundamentals of how dampers operate.

How about actually reading it this time.

Notice the distance travelled by softer damper at the same time. At the same time softer damper travelled longer distance than stiffer damper. At the same x axis value, softer damper already travel more y axis value.

And!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Great it shows that stiffer damping react physically more slowly that softer damping, which is exactly what I have always said. The stiffer damper has travelled less distance in the same period of time, its moving slower. Sucahyo, it’s you that has disputed this not me. Once again if stiffer damping slows down suspension movement and GT4 dampers set to 10 show a ‘delay’ or slowed movement then higher values are stiffer.

And the delay you are talking about is not like that, you are talking suspension waiting the force to reach certain value before it move, where the graph show both move right away. I see that you have difficulty of reading graph, I try to avoid using graph later. It seem that you don't know how the graph difference of late reaction and imidiate reaction. The graph show that all damper speed decrease over time. Faster initially and then reduced later. When the time vs movement graph show steep hill at first and flat hill later it means the speed is reducing.

No I used that to try and illustrate a point, as I said above (and previously – although you seem to want to try and ignore it) it was purely illustrative and not 100% accurate. I could level similar criticism at your syringe model for dampers, but it would be both petty and pointless.

I don’t have any difficultly at all in reading the graph and certainly do not need your rather condescending tone, particularly as the graph in question related to mass-dampers and was initially (and repeatedly) referenced in a misleading manner by yourself.

Stiffer dampers and springs will cause more body roll:
- when the inside tire hit bump, yes
- When the inside tire do not hit any bump, no, the opposite.

Don’t simply state this, explain exactly why you believe this to be the case (as some independent sources would be nice as well).

There is no use talking about that when our understanding about damper is different. I already mention in my old post that caterham behaviour happen because higher damper is softer.

Your explanation was that what we see and feel in the straight-line brake test was not the slowing of the suspension movement but the loading of the tyre being spread over a longer period of time, I quote….

I test caterham too, and get visual and sound impression close to your result.

I use this Skip Barber quote as reference:
"A stiffer bump setting slows down the motion on its corner and 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."

delay = late = longer period of time.

…now the problem with this is that you can’t actually see the loading of the contact patch, nor measure how long it takes. Simply put GT4 does not provide us with the tools to do so.

What we can see quite clearly is that using higher damper settings the suspension reaction is slowed (both in visual and feel), you even acknowledge this yourself. Simply put this is a clear indicator that higher damper values are stiffer in GT4 and to deny this is to contradict a lot of what you have said yourself in the above syringe explanation.

not neccesarily on car. What a stationary damper (one end attached to solid object) do when it receive force. Don't answer it just by "it sink", answer it more descriptive please. Answer how damper react, and also what is the difference between stiff and soft. Is it too hard for you to explain the sink difference between soft and stiff, which one reach bump stop faster, what happen to the force when soft or when stiff?

I’m sorry Sucahyo I totally fail to see what purpose this will serve and as far as I am concerned it’s a totally pointless distraction. Exactly when are we ever going to use this and what is the purpose of this question?

Again, you do not differenciate soft damper and stiff damper.

Sucahyo if you are so damn clever then you tell me what will happen in this completely pointless and irrelevant question. This is a distraction from the main point of issue here, that you are unable to provide any proof that GT4 damper values are reversed. The question above will not help in any way to address that.

Simply because your explanation is too inadequate that I have to do a lot of guessing. many question still not answered. What you use to explain some real life or GT4 behaviour can't be use to explain other behaviour.

Actually Sucahyo I think its more a case that you are unwilling to accept that you may well be wrong, every single thing I have said I have supported with accurately and clearly identified sources and links. What you then do is refuse to accept these sources or try and interpret them in a manner that no one else does (or refuse to accept them because they don’t contain the exact word you want). A good example of this would be the issue of damper rates and harshness, I provided countless link (from suspension and damper manufactures) that clear show this to be the case (and this is harshness not ride comfort which are not the same). You then dismiss these sources are wrong and provide a source of your own that does not even back up what you say.

Lots of questions have been answered, you just refuse to accept anything that does not support your GT4 dampers are reversed idea.

I guess the final result is I am the only one in the world who think GT4 damper is reversed.

And does that not tell you something?


Scaff

 

[sucahyo]

So you fully acknowledge that you have used a diagram representing mass-dampers in buildings and presented it as an illustration of automotive damper reactions (and done so numerous times), yet not felt the need to let anyone know that it did not represent automotive dampers.

I don't intent to hide it, I post link to the article I use. And I don't see what make an automotive damper so special, it still work the same way as other damper do, dampen vibration. So even building damper pricipal still can be used.

When you used in within this discussion you clearly used the term “suspension movement” twice in reference to the diagram, a diagram which has nothing to do with suspension movement in the automotive sense. Do you not see just how misleading this appears?

Both has the same graph. It's not wrong, why it should be misleading?

I’m also going to take rather a large issue in this post to you once again attempting to make it appear that I have said something that I have not. I have maintained (and quoted from a number of sources) that stiffer dampers slow down suspension reaction, something that the diagram does clearly show and you admit clearly shows.
...
I don’t have any difficultly at all in reading the graph and certainly do not need your rather condescending tone, particularly as the graph in question related to mass-dampers and was initially (and repeatedly) referenced in a misleading manner by yourself.

It's obvious that you have difficulty reading graph, and somehow I doubt you can make one. Try to make graph out of what you post.

If you don't want to do this bellow, fine, I don't want your head blow because of this.

First, graph from:
"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."

"As I said in my last post If the suspension system is too stiff then it will be unable to react quickly enough to the force it encounters. The excess of force has to go somewhere, and it is transferred to the cars body (this is not conjecture) and the result can be that the cars body is forced up, this is not a result of your strange ‘re-jump’ term, rather something that occurs during the bound phase when the suspension is too stiff to respond quickly enough to the force placed upon it."

When you try to make graph that describe this behaviour you will see the error of your statement. Draw graph of the relation between damper stiffness and force receive by car. Damper stiffness as x axis, force received by car as y axis, use linier scale. My hint? draw vertical line (stupid, but that is how I translate your post).



Second, graph from
"GT4 does not actually give us the tools to be able to directly see how the contact patch of the tyre loads and unloads, but the Caterham does allow us to see and feel the delay in suspension reaction to the load transfer (“slows down the motion” from Skip Barber) and this reduces the time available for the load transfer (“speeds up the load transfer” from Skip Barber). Soft dampers on the other hand have less resistance and as such will begin to react quickly (“allows the suspension to move faster” from Skip Barber) and as a result the load transfer itself starts sooner and therefore has more time to spread the load (“spread the changes in loading out over a longer period of time” from Skip Barber)."

"Now the above is a very, very simple look at how this works (its actually not 100% accurate either as load transfer is occurring ‘through’ the damper when its not reacting – but it does help ‘visualise&#8217."

"Yes dampers do work in this way. The stiffer the damper the more force is required to compress it. As suspension movement does not happen immediately, until the force required to compress (or rebound) the damper has been reached it will resist the force."

"Now as the stiffer damper will resist compression/rebound until the greater load is placed upon it this will delay the reaction of the suspension. However as the total load transfer will take a fixed amount of time, the longer the delay, the less time a stiffer damper has to load/unload the tyres contact patch and the quicker that load/unload will occur."

Draw a graph of the relation between time and visual suspension movement. Time as x axis, visual suspension movement as y axis, linier scale. Draw two curve, soft damper curve and stiff damper curve. My hint? draw horizontal line followed by curve.



BTW, I forgot about the Italic part, "However as the total load transfer will take a fixed amount of time", from what source do you get this?

Soft damper and stiff damper has the same amount of total load transfer time? Damper can not change the total load transfer time then? Aren't you fogetting this Skip Barber quote:
"A stiffer bump setting slows down the motion on its corner and speeds up the load transfer"

Which is exactly what we see and feel in the Caterham with dampers set to 10, in the straight line brake test, the dampers acting as an anti-dive device.

and still dive after that.

Stiffer dampers slow down or delay (take you pick in descriptive terms) the reaction of the suspension,
...
Great it shows that stiffer damping react physically more slowly that softer damping, which is exactly what I have always said.

No, it does not react slowly, but it move slowly. Try to learn to read the graph Scaff. Horizontal line in time vs movement graph mean thing do not move over time, vertical line mean thing move in a single time. late reaction would show as a horizontal line followed by curve. While slow movement show as low angle diagonal line.

Look at the left top corner of the graph:


At about 0.1 x axis you should see that all three damper stifness curve collide. It means Scaff, at 0.1 second or something all three damper stiffness move at the same speed, at the same distance. This means all three damper stiffness have the same reaction time, since all three of them already react and move at the same manner.

and when Skip Barber says: "slows down the motion" (stiff damper) it does not mean "slows down the reaction".

when Skip Barber says: “allows the suspension to move faster” (soft damper) it does not mean “allows the suspension to react faster”.

Don’t simply state this, explain exactly why you believe this to be the case (as some independent sources would be nice as well).

About stiffer damper will increase body roll when inside tire meet bump:


The link do not describe how car body react when the inside tire meet bump. It explain how car body react during cornering.

When the car do cornering, the corner inside damper and spring force will pull the car body while the outside damper and spring force will push the car body. When the inside tire meet bump, the bump will create force. Damper and spring will try to resist and absorb the force, this will create force that push the car body. This can change the current force direction of inside force, from pull to push. This will increase car roll.

Your explanation was that what we see and feel in the straight-line brake test was not the slowing of the suspension movement but the loading of the tyre being spread over a longer period of time, I quote….

I mean my post far back, like:
"Your test result is about the same as mine although with much more greater detail , but the conclusion is different. IMO, more jump and vibration can be caused by softer damper. Stiffer damper will prevent jumping and vibrating better."

"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."

I don't think jump visual in GT4 is an error, and I don't believe vibration in GT4 is an error too.

What we can see quite clearly is that using higher damper settings the suspension reaction is slowed (both in visual and feel), you even acknowledge this yourself. Simply put this is a clear indicator that higher damper values are stiffer in GT4 and to deny this is to contradict a lot of what you have said yourself in the above syringe explanation.

Softer damper make suspension move in a longer time, this is what we see as late reaction in your caterham and range storm test. Stiffer damper stop supension movement quicker, show as faster reaction, faster roll, faster braking, non jelly reaction, etc.

I’m sorry Sucahyo I totally fail to see what purpose this will serve and as far as I am concerned it’s a totally pointless distraction. Exactly when are we ever going to use this and what is the purpose of this question?

This and experience riding harsh ride on a car with damper too soft:
- Show your understanding about damper, the information from you usually only apply on certain behaviour and can not be applied on other behaviour (inconsistent damper physics).
- If you can't explain the difference between soft or stiff damper in many situation, I don't expect you to know how to judge GT4 damper.
- If you can't tell what soft damper do or what stiffer damper do in many situation, I just can't trust your opinion about GT4 damper lower is softer.
- I ask you to explain how different damper stiffness react or move in an isolated way to know, wether you really know about damper or you just think think that you know. "it sink" is not the kind of answer I expect from someone who know about how damper react or work.

Your explanation consistency is a big problem.

I bet it will be impossible to explain all of this consistently:
- stiffer damper has slower reaction
- very stiff damper bypass suspension and transfer force directly to car
- stiffer damper "slows down the motion"

On soft damper explanation the number two explanation give error.

Try to mention all of this when you explain how damper work, can you?
To repeat:
Scaff, can you explain how damper work when receiving single direction movement (bump) without spring equipped?
What happen when the tire receive bump, second by second until right before the suspension bottomed out, with the assumption that the k1 and k2 is null. How the speed change, what is the difference between stiff and soft damper, how much force recieved by the car, how much force is lost, how much different the damper will react on different bump speed, etc.

not neccesarily on car. What a stationary damper (one end attached to solid object) do when it receive force. Don't answer it just by "it sink", answer it more descriptive please. Answer how damper react, and also what is the difference between stiff and soft. Is it too hard for you to explain the sink difference between soft and stiff, which one reach bump stop faster, what happen to the force when soft or when stiff?

A good example of this would be the issue of damper rates and harshness, I provided countless link (from suspension and damper manufactures) that clear show this to be the case (and this is harshness not ride comfort which are not the same). You then dismiss these sources are wrong and provide a source of your own that does not even back up what you say.

Ok, stiffer damper make ride more uncomfortable (harsh), but I don't agree that stiffer damper make more suspension movement (vibration) and noise (sound harsh), your source don't even mention this while my real life experience said no.

 

[Scaff]

I don't intent to hide it, I post link to the article I use. And I don't see what make an automotive damper so special, it still work the same way as other damper do, dampen vibration. So even building damper pricipal still can be used.

Both has the same graph. It's not wrong, why it should be misleading?

Really well lets have a look at that shall we. First I have already agreed that the basic principals are the same, so do not try and make out otherwise. Secondly if mass-dampers are no different to normal automotive dampers would you care to explain why Renault’s Formula One team was banned from using a mass damper in its car this season? The mass damper was not being used by them as a replacement for the standard dampers, rather to assist in the reduction of vibration and disruption to the car, to aid the aerodynamic balance and characteristics of the car. The FIA banned it for being a ‘moveable aerodynamic device’, had it been considered a true suspension component it would not have been banned.

The basic principals of the two are similar (as I have repeatedly said), but they are not directly interchangeable, to present one as the other without clearly stating so is miss-leading.

It's obvious that you have difficulty reading graph, and somehow I doubt you can make one. Try to make graph out of what you post.

If you don't want to do this bellow, fine, I don't want your head blow because of this.

Suchayo at what part of this do you want to stop with the personal digs and near insults, before or after you get an infraction for it?

Am I going to draw your graphs and diagrams? No, the reason being as you will read below I have quite honestly had enough of this messing around, I’m beginning to reach the point were I thing either you are incapable of understanding what I am saying or you are deliberately trying to manipulate what I have said in a manner that was never intended. I have explained and re-explained these things over the course of the last year; the only person who has failed to grasp them is you. The common factor here is quite simply you, its seems to me that when you have failed to grasp what is said to you (by members here or from source material) you resort to re-wording things or simply insulting people.

BTW, I forgot about the Italic part, "However as the total load transfer will take a fixed amount of time", from what source do you get this?

Soft damper and stiff damper has the same amount of total load transfer time? Damper can not change the total load transfer time then? Aren't you fogetting this Skip Barber quote:
"A stiffer bump setting slows down the motion on its corner and speeds up the load transfer"

And you seem to be forgetting this…

"Now the above is a very, very simple look at how this works (its actually not 100% accurate either as load transfer is occurring ‘through’ the damper when its not reacting – but it does help ‘visualise&#8217."

…which must be a bit embarrassing for you, as you did quote it back to me as well.

and still dive after that.

Yes, I don’t believe I said it would stop all dive, nor did the quote I gave.

No, it does not react slowly, but it move slowly. Try to learn to read the graph Scaff. Horizontal line in time vs movement graph mean thing do not move over time, vertical line mean thing move in a single time. late reaction would show as a horizontal line followed by curve. While slow movement show as low angle diagonal line.

I said “react physical” meaning movement, so rather than (once again) trying the cheap insults its you that should read things a little more carefully.

Look at the left top corner of the graph:


At about 0.1 x axis you should see that all three damper stifness curve collide. It means Scaff, at 0.1 second or something all three damper stiffness move at the same speed, at the same distance. This means all three damper stiffness have the same reaction time, since all three of them already react and move at the same manner.

and when Skip Barber says: "slows down the motion" (stiff damper) it does not mean "slows down the reaction".

when Skip Barber says: “allows the suspension to move faster” (soft damper) it does not mean “allows the suspension to react faster”.

So Sucahyo does only the first 0.1 second of the graph count? If so why.

Looking at that graph (and working with X = Time and Y = Distance moved – most likely damper shaft) the lines do not converge (collide) at 0.1 seconds, they diverge (separate). The only way you could possibly say they are colliding or converging is if you were to be reading the graph backwards, but that would mean that time (x-axis) would be going backwards (from 4 seconds to zero) which is not very likely.

Looking at the movement starting at “1” and calculating the time taken to reach “0.2” on the y=axis differs for each line.

Green (under-damped) = 0.45 seconds (approx)
Red (critically damped) = 0.75 seconds (approx)
Blue (over-damped) = 1.15 seconds (approx)

So the time taken to move the same ‘distance’ increases as damper stiffness increases, and I have not said otherwise.

Or we could look at it in terms of distance travelled in 1 second (distance of what is not clear as neither of the axis on the graph is actually labelled and you have not been clear about what the y-axis is actually the movement of or the units of scale in place).

Green (under-damped) = 5 units of movement (approx), from 1 to -3.5 and then back up to -3.0

Red (critically damped) = 0.95 units of movement (approx), from 1 to 0.05

Blue (over-damped) = 0.75 units of movement (approx), from 1 to 0.25

So quite clearly the stiffer the damper the less distance travelled in a set period of time, which exactly matches what we see with higher value dampers in the Caterham Stright-line brake test.


I think that it’s also very important to note that the graph you have used is based on purely mathematical modelling of the Critical Damping Co-efficient and it not taken from actual shock dyno plotting. I’ve already quoted a few sources on how this does not always translate into how a car will exactly react or feel on track. What we are looking at here is how the theory works, which is why I also posted the following, which you seem to have not read.

One very big advantage of a damper that can be altered separately on bump is that it can be used as an anti-dive or anti-squat device. This is because for a very short interval after loads are fed into the suspension, the car 'feels' a hard damper as almost solid.

About stiffer damper will increase body roll when inside tire meet bump:


The link do not describe how car body react when the inside tire meet bump. It explain how car body react during cornering.

Which is great if we were discussing body roll (or more specifically from the paper in question vehicle roll-pover), but that’s not what you were claiming. You said that

Stiffer dampers and springs will cause more body roll:
- when the inside tire hit bump, yes
- When the inside tire do not hit any bump, no, the opposite.

The above does not discuss this at all, and as such does not support your claim at all. Not only that but it discusses a single vehicle with fixed damper and spring rates, it does not address changes in damper and spring rates and there effects at all.

When the car do cornering, the corner inside damper and spring force will pull the car body while the outside damper and spring force will push the car body. When the inside tire meet bump, the bump will create force. Damper and spring will try to resist and absorb the force, this will create force that push the car body. This can change the current force direction of inside force, from pull to push. This will increase car roll.

First of all what part of the corner? Entry, exit or constant radius?

As you do not discuss front or rear separately lets assume its constant radius, well first off the inside suspension will be in low-speed rebound (load is/has been transferred off the suspension and it is reacting to this) and the outside suspension will be in low-speed bound (load is/has been transferred onto the suspension and its reacting to this). The body roll (from inside to the outside) has been caused by the load transfer.

Should one or both of the inside tyres now hit a curb it will almost certainly be in the high-speed damping area (normally classed as damper shaft velocities above 1 inch/second – source Penske) and more importantly this move into bound is caused not by the movement of the sprung mass (roughly the car body), but rather the un-sprung mass (wheel, tyre and all un-sprung suspension components).

Your own explanation of this totally fails to differentiate between suspension forces caused by two differencing sources (sprung and un-sprung) and the differing damper reactions that can occur as a result (lo and high speed damping).

I mean my post far back, like:
"Your test result is about the same as mine although with much more greater detail , but the conclusion is different. IMO, more jump and vibration can be caused by softer damper. Stiffer damper will prevent jumping and vibrating better."

"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."

I don't think jump visual in GT4 is an error, and I don't believe vibration in GT4 is an error too.

The problem with this is quite simply that it is not supported by any outside source; every single one quoted disagrees with you. In fact they directly contradict you.

The following is taken from a Penske Technical Manual.

Compression
The idea is to set the compression damping forces to suit the bumps in critical areas, such as corners, corner exits and braking zones.

Increasing or lowering cannister pressure (range 150 to 300psi) can have an influence on support under braking, acceleration, and tyre loading on turn-in, and mid-corner grip.

Step 1 -Set the rebound adjuster to full soft.
Step 2 -Starting with the compression set at full soft, drive a lap then return to increase the bump settings. Continue this process of adding bump control to minimize the upsets until the car becomes harsh, loses tyre compliance and traction. At this point you know that you have gone to far on the compression settings; back off one click.


Rebound
The idea is to tighten up the car; stabilise the platform and eliminate the floating 'Cadillac feeling'. It will also reduce the rate of body roll.

Step 1-With the rebound setting at full soft, add five flats or clicks of rebound adjustment at a time, then continue the process until the car becomes skittish or the rear wheels hop under braking. At this point you know you have gone to far on the rebound side, back off one flat or click at a time for the final balance.


or we could take a look at Allan Stainforth (from Race and Rally car source book).

Bounce, wallow, lurch into corners - too little rebound damping.

Car jacks itself onto the bumpstops because the coil is too weak to fight against the damper - too much rebound damping.

Grounding, lurch onto the front or rear corner, excessive squat or nose diving - too little bump damping

Very hard ride, wheel hop sideways in corner - too much bump damping.

Now both of those quite clear say that an increase in harshness, skittish behaviour and hard ride are a result of an increase in damping.

And

Q: Won't high spring rates make the ride harsh?
A: No. The primary function of the spring is to control the roll of the vehicle. Body roll, brake dive and acceleration squat are all functions of spring rate. By increasing the rate of the spring, you decrease the movement of the body. Ride compliance and harshness are more a function of high speed damper compression resistance than spring rate

And this, first posted by myself over a year ago

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.

These have all been posted multiple times now and you seem to ignore, dismiss or re-word them to try and suit your own beliefs. The simple point of fact is they contradict what you are saying.


.

Softer damper make suspension move in a longer time, this is what we see as late reaction in your caterham and range storm test. Stiffer damper stop supension movement quicker, show as faster reaction, faster roll, faster braking, non jelly reaction, etc.

No, no, no.

The quotes I have provided above and on numerous occasions do not support what you are saying here. Allan Staniforth quite clearly says that stiff/hard damper can be ‘felt’ as almost solid when load is applied, showing that a tiny delay in any visible movement is a characteristic of stiffer dampers. In addition the graph you posted above shows that over the same time period and for the same load a stiffer damper will move ‘less’ than a softer damper (under-damped vs critical damping vs over-damped).

Your explanation does not even match your own sources.

This and experience riding harsh ride on a car with damper too soft:

First off Sucahyo your own real world experience of a wide range of cars on a wide range of surfaces, but in particular very stiff set-ups on smooth track surfaces, is by your own admission limited.

Secondly you have failed time and time again to show any proof of experiencing a harsher ride (uncomfortable maybe) on softer dampers. Yet I have provided multiple sources, from racing damper and suspension manufacturers that clearly states that firmer dampers = harsher ride.

- Show your understanding about damper, the information from you usually only apply on certain behaviour and can not be applied on other behaviour (inconsistent damper physics).

I would like some examples of how my information is inconsistent. Almost every single thing I have posted is supported by reputable source material. You on the other hand have a history (that still persists) of presenting your own theory as fact, of misleading members over testing you have carried out (or not carried out as the case may be), not supplying source material and when you do cite sources you have often misquoted or miss-understood them. For example, the source you provided to ‘prove’ that stiffer dampers were not harsh did nothing of the sort; you completely failed to actually understand your own source material. I read every word of that document and at no point did it state that stiffer damper did not increase harshness. You took references to ride comfort and used them to try and support your own theory.

In addition its not just me that you are saying does not have an understanding of damper technology, but also almost every other member who has posted in this thread and the source material authors that I have used (as I have remained consistent with that source material).

- If you can't explain the difference between soft or stiff damper in many situation, I don't expect you to know how to judge GT4 damper.

Uh I can and have, not only that but I have real world experience of this and have also trained in the area of vehicle dynamics and suspension. Once again I ask what exactly qualifies you, the person who a year ago said they did not really care how GT physics worked, but preferred to reverse engineer it.

Maybe, but, since I don't work in automotive area, even though its nice to know what the real life physics does, I prefer reverse engineer GT physics for my tuning.

In addition I think its worth remembering that you actually made your mind up about GT4 damper values being reversed before you actually had any real experience of GT4.

- If you can't tell what soft damper do or what stiffer damper do in many situation, I just can't trust your opinion about GT4 damper lower is softer.

When exactly have I failed to discuss or explain a real world situation or application of soft vs stiff dampers?

I have dismissed your ‘nonsense’ requests repeatedly as they have no relevance to either the real world or GT4, your persistence with them is also rather tiring as they serve purely as a distraction and are of no constructive use.

- I ask you to explain how different damper stiffness react or move in an isolated way to know, wether you really know about damper or you just think think that you know. "it sink" is not the kind of answer I expect from someone who know about how damper react or work.

Your explanation consistency is a big problem.

I bet it will be impossible to explain all of this consistently:
- stiffer damper has slower reaction
- very stiff damper bypass suspension and transfer force directly to car
- stiffer damper "slows down the motion"

On soft damper explanation the number two explanation give error.

No it does not, the issue here is with your understanding of this and I believe miss-reading (and I hope not deliberately) what I am saying. I have explained these areas a huge number of times and the only person who has an issue with them is you.

I must say that I do in particular like this part...

I ask you to explain how different damper stiffness react or move in an isolated way to know, wether you really know about damper or you just think think that you know

..., may I ask what exactly qualifies you to even judge if I am right or wrong on any automotive topic. Specifically what work have you do within the motor industry, training attended, etc. I ask because a little over a year ago you had no knowledge at all of damper physics and reactions, now unless you have attended some specific training in this area, I strongly suspect that you are the one lacking in formally tested knowledge.

To be blunt about it you have dismissed every other member here at GT Planet in regard to our understanding of dampers and categorically stated that our understanding of every single piece of source material is incorrect, and your qualifications for this are the info you have picked up off the 'net in the last year, most of which is written in rather technical terms in a language that is not native to you. Once again Occam's Razor comes into play here, put simply it is far more likely that you are the one who is incorrect and has failed to interpret the source material, than for every single other member involved to have done so (oh and every engineer and automotive lecturer I have spoken on the subject with as well).


Put more specifically Sucahyo a large amount of your input into various discussions on tuning has either been poorly thought out, flawed or just plain wrong. You have failed to prove you point in regard to the issue of reversed damper values, in addition you have failed to 'prove' the merit of your own tuning theories and have sailed so close to AUP violations that is got beyond a joke.

Try to mention all of this when you explain how damper work, can you?
To repeat:
Scaff, can you explain how damper work when receiving single direction movement (bump) without spring equipped?
What happen when the tire receive bump, second by second until right before the suspension bottomed out, with the assumption that the k1 and k2 is null. How the speed change, what is the difference between stiff and soft damper, how much force recieved by the car, how much force is lost, how much different the damper will react on different bump speed, etc.

not neccesarily on car. What a stationary damper (one end attached to solid object) do when it receive force. Don't answer it just by "it sink", answer it more descriptive please. Answer how damper react, and also what is the difference between stiff and soft. Is it too hard for you to explain the sink difference between soft and stiff, which one reach bump stop faster, what happen to the force when soft or when stiff?

OK I don’t know what it will take to get this through to you, and my patience is wearing very, very thin.

What happen when the tire receive bump, second by second until right before the suspension bottomed out, with the assumption that the k1 and k2 is null

If k1 and k2 are null then the car will already be bottomed out, why can’t you actually understand this, dampers don not support weight at all, without the springs in the system nothing is supporting the sprung mass at all. The car will already be bottomed out (sat right on the bump stops).

As an example this has no relevance what so ever, it serves no purpose at all and has no real world application in any way and I have go as far with it as I am willing to.

When I reopened this thread I did so under a number of conditions, and just to remind you they were:

However I open it again on a couple of provisos
1. Any test discussed must have been carried out by the member who posts it and full settings must be included
2. Opinion as fact will not be tolerated, sources must be provided
3. The AUP will be enforced to the letter

You have failed to meet a number of these provisos and quite frankly I’m on the verge of locking this thread once again. Your question has nothing at all to do with proving one way or another if GT4 dampers are soft or firm at higher values. Stop with the crap and do it right now.

Ok, stiffer damper make ride more uncomfortable (harsh), but I don't agree that stiffer damper make more suspension movement (vibration) and noise (sound harsh), your source don't even mention this while my real life experience said no.

I do love the way you accuse me of not being able to read things and then post the above. I did not say that stiff dampers will make the ride more uncomfortable, I said (and have backed up with numerous sources) that stiffer damper are harsher. Comfort will depend on far more than this and can be a personally matter, I don’t find my Celica uncomfortable at all, but my wife does, I would however never dispute that over broken road surfaces it’s a harsh ride.

In regard to inconsistency you are now saying that you “don't agree that stiffer damper make more suspension movement”, well that’s great because I’ve never said that they would. It’s rather a pointless thing to say in that context.

In regard to your real-life experience, well that we have already covered on a number of occasions, you did not work on the car yourself, you are trying to cover all areas of NVH under the remit of dampers and are not actually able to prove that a firmer damper was installed rather than a replacement for a faulty damper.

Most concerning of all you have failed to address why everyone else disagrees with you, and more importantly why you have not been able to come up with a test that repeatedly proves that GT4 dampers are reversed. I have come up with a huge number of differing tests to support my position and when run by other members they are all in agreement, higher values are stiffer. Now either we are all wrong and the only person here who actually understands damper is you, or you are wrong. Given that the majority of consensus (following round after round of tests) is that higher values are stiffer and that a number of members who have commented and run these tests have experience with adjustable damper and actual track experience I find it far more likely that you are wrong.

So I tell you what, stop all the rubbish and put together a series of tests that clearly show (under a range of damping situations) that higher damper values in GT4 are indeed softer. However you have to ensure that these results will match with real-world damper reactions, these should be sourced and relate to automotive damping reactions.

Basically what I am saying is ‘Put up or Shut up’

Scaff

 

[sucahyo]

Ok, I shut up.

I still consider you have incomplete knowledge about damper, still think you can't read graph, and will always think that GT4 damper is reversed.

Have a nice day.

 

[Mt. Lynx]

ignore

 

[Greycap]

I know that maybe I shouldn't express my feelings here but I'll do it anyway. Flaming incoming or not. I've been reading this thread for a long time and have a clear opinion who is right.

The situation is almost the same as if someone was saying that elephants are light blue... without never seeing an elephant or a picture of it. Then the person is given a load of pictures and videos of grey elephants, even sees an elephant in first person, but still claims that they must actually be light blue because that's how "it just has to be".

Hats off for Scaff for being as patient as he has been. 👍

On topic, the dampers in GT4 are very logically non-reversed. It doesn't take a space engineer to tell this, just a normal player that can remember how the car handled with settings X and compare them to settings Y. Higher values give sharper handling but can cause skittish behaviour on bumpy surfaces, sounds very much like stiffer dampers. No doubt, at least for me.

- R -