Step by step tuning Alpine A310

sucahyo · Dec 20, 2006

Scaff
I am however interested to hear you say that you now believe that PD modelled faulty damper for GT4! Now why on earth would they do that?

Road car would not feel comfortable using track stiff damper. And I don't think manufacturer will equip road car with damper over powering spring rate.

I use "faulty" term to indicate a very soft damper value that make spring rate osccilate like crazy when passing road irregularity. Something that I see in default FC suspension setting in GT4 Lotus Elise in Deep Forest.

Scaff
All of the above videos (the top one being one of the most famous BTCC moments ever) quite clearly show that just because a car is running a stiff set-up (and please do not try and claim otherwise you cant run ride height that low and not run stiff) does not mean that a cars movement is totally controlled. They will still buck and move, sometimes it will look a little like bouncing, but it is most certainly not a result of a road car set-up or faulty dampers.

The second clip was from a race event (at Silverstone) that I actually attended earlier this year and I was in the stands right in front of that incident.

And how exactly do you know for a fact that these cars were running faulty damper?

I guess you lucky can see it personally, but what do you mean by "look a little like bouncing"?

Sorry, I can't watch all that video, I can't watch any youtube video. But I already see some old BTCC video. I see that they show stiff spring rate, but still allow some trailing bounce which indicate that the damper setting is not over powering spring rate. Agree that those bouncing is the result of using a very stiff spring, but without soft damper, car wouldn't do trailing bounce. Those bouncing is not the result of using stiff damper.

Just compare this video with my GT1 video and GT2 video. And see which has closer similarity. GT1 video show the same behaviour as Viper Racing car using soft spring and very stiff damper. GT2 video show the same behaviour as Viper Racing car using very stiff spring and soft damper.

1989 BTCC Race RS500 in Birmingham
rear bumper camera
podium camera
another podium camera
cockpit camera

I see this video a lot more similar to GT2 Supra video. Where stiff spring rate make the bouncing frequency high (fast bouncing) and soft damper make the bouncing last a bit longer.

And I am firmly believe if they reduce the spring rate stiffness, the trailing bounce will be reduced. If they increase the damper stiffness the trailing bounce will also be reduced. If they reduce the damper stiffness the trailing bounce will be increased. If they use an very stiff damper to the point it overpowering the spring rate, the trailing bounce will not happen, but instead the very jerky, jumpy movement happen, and I think in every bump it will be in danger of loosing control.

here is GT2 PAL supra which show bouncing more clearly

Scaff
What exactly do you think the Racing Suspension is trying to model?

Just to provide a more complete setting option like usually available when tuning race car.

Scaff
Why do you think the options go Sports, Semi-Racing and then FC Suspension?

Trying to immitate the level of detail included when tuning car. But I have no clue why they only included stabilizer in the most expensive upgrade. And besides, isn't single adjustable damper in real life only provide damper rebound adjusment? And yet PD provide both bound and rebound connected together.

Scaff
Why do you find it unlikely that PD would allow you to equip racing suspension suitable for a track in a game that involves racing cars on tracks and also includes racing cars (which share the exact same set of suspension tuning options as the FC suspension)?

Don't know, maybe change of mind. They provide more range, from very soft to very stiff damper in GT1, and provide very soft to soft damper in GT2 and GT4.

Scaff
Real World harshness, both in terms of ride quality and sound are very, very variable qualities. For a start you would have to separate Primary and Secondary ride quality, then look at the car itself and the level of soundproofing that had been used, etc, etc. Thats a far more variable set of circumstances.

Sure, but telling the difference in my dad's car tire & suspension noise when using different damper is very easy. Quieter sound when using new damper, from very harsh to more calm, from brrrrrrush to bapbapbap.

Scaff
Thats now the second time you have tried to make out I have said something that I did not.

You seem don't realize it. This:

Scaff
GT is obviously far simpler, and from my testing (all other factors being equal) as you increase the damper stiffness the sound and feel gets harsher.

and this:

Scaff
No I have not, Ive said that stiffer dampers increase vibration and produce a harsher sound, not that they are the only cause of this.

Is different.

If you really think that stiffer damper is not the only cause of increased vibration and produce a harsher sound what you say should be:

"GT is obviously far simpler, and from my testing (all other factors being equal) as you increase or reduce the damper stiffness the sound and feel gets harsher depend on wether current damper is too stiff or too soft."

Italic part added.

When you say:
"GT is obviously far simpler, and from my testing (all other factors being equal) as you increase the damper stiffness the sound and feel gets harsher."

You already make an assumption that current damper is already stiff. How do you decide this? I hope this is not chicken and egg situation.

Remember that car can jump around because softer damper too. In viper racing, the behaviour of jumpiness caused by stiff spring soft damper can be made look like soft spring and stiff damper. Without noticing the trailing rejump after, it would be hard to notice the difference from bumper view.

Scaff
For a start you are assuming here that no difference in the physics engine is present between GT and GT2, and from my own analysis that again is not true at all.

I have another difference. Something that can easily explainable if we assume both using different damper tuning direction.

The jump that we see in GT1 Supra video, will still happen if you change spring rate value to minimum. The jump will reduce a lot if you reduce damper value. An obvious clue that damper overpowering spring so much that changing spring rate value only change the condition a little.

The jump that we see in GT2 Supra video, will reduce a lot if change spring rate value to minimum. The jump will only reduce a little if you reduce damper. An obvious clue that spring rate overpowering damper so much that changing spring rate value will change the condition a lot.

In summary:
In GT1 the factor for jumpy ride is damper, 10 damper will make the car jumpy.
In GT2 the factor for jumpy ride is spring rate, max spring rate will make the car jumpy.

You may call this the difference of physical engine. For me it is a clue that damper in GT2 is reverted.

In GT4 spring rate has so much effect in car jumpiness compare to damper, this should be taken as clue that spring rate overpowering damper. And when spring rate stronger than damper, the damper it self is weak (soft). Weak damper can't make the car jump around.

And you still don't answer:
"And do you not notice how easily we can reduce car jumpiness in GT4 by reducing spring rate?"

Scaff
Im far more interested in the actual settings you used in GT and GT2 here, not the Viper racing series settings, that I can actually look at in some meaningful way.

Are you still interested to do test in another game?

Scaff
Ive highlighted in bold the six lines you missed out and would like to know exactly why you missed them out.

I use the quote to show you that in GT4 you see soft damper behaviour, not stiff. Something that you even said it yourself (wallow). It's to answer your post:
"And nor do the cars in GT4 feel 'boeing, boeing' with high damper settings, GT4's damper settings do not allow you to set truly soft values (not as represented by every other sim in the last list I posted."

In that post I assume that you are saying damper in GT4 do not have soft under the adequate "just right" value, the damper tuning have range from above right amount to overly stiff. Where I believe it's the opposite, from bellow the right amount to overly soft.

I see wallow wallow as as sign as soft damper. Sign of damper being overpowered by spring rate. Sign of damper weaker than even the softest spring rate. And when this weak damper paired together with stiff spring rate (Subaru 360 with stiffest spring rate), it will result in much bouncing around. Jump happen because spring rate made that happen.

If we think suspension force equal to spring rate plus damper.

A damper that can't make the car jump around without the help of spring rate is weak damper (GT2 and GT4 case).

And a damper that can make the car jump around without the help of spring rate is strong damper (GT1 case).

Scaff · Dec 20, 2006

sucahyo
Road car would not feel comfortable using track stiff damper. And I don't think manufacturer will equip road car with damper over powering spring rate.

What are you talking about, I asked why you said that PD had modelled ‘faulty’ dampers in GT4 and you come back with some nonsense about manufacturers? This is the FC suspension upgrade we are talking about here, it is meant to represent a full replacement of the stock suspension system with one that is tuned for motorsport use.

sucahyo
I use "faulty" term to indicate a very soft damper value that make spring rate osccilate like crazy when passing road irregularity. Something that I see in default FC suspension setting in GT4 Lotus Elise in Deep Forest.

Having driven the Elise a number of times, even on the default settings I can’t recall any oscillation at all.

sucahyo
I guess you lucky can see it personally, but what do you mean by "look a little like bouncing"?

I mean it looks a little like bouncing from under-damping, but its not. Do you not even have access to a PC that will let you view these, because it’s rather difficult to run around trying to find videos that you can watch when so many are easily available on youtube.

http://www.berlinasportivo.com/marquespec/Alfa/Video/Alfa155btcc.wmv
http://www.berlinasportivo.com/marquespec/Alfa/Video/Alfa155btcc2.wmv

There we go, they are quite big (for dial-up) at 20-25meg each. They focus on the Alfa 155 in Touring Car form, but also include a lot of BTCC footage.

sucahyo
Sorry, I can't watch all that video, I can't watch any youtube video. But I already see some old BTCC video. I see that they show stiff spring rate, but still allow some trailing bounce which indicate that the damper setting is not over powering spring rate. Agree that those bouncing is the result of using a very stiff spring, but without soft damper, car wouldn't do trailing bounce. Those bouncing is not the result of using stiff damper.

And you have seen or sat in one of these cars? Watched them race for over a decade? No, I think is the likely answer. Yet from less than a minutes worth of footage, from one track (the single most bumpy road track ever used in the BTCC and one that has not been used for well over a decade) you are in a position to say exactly what is going on with the cars.

Are you sure you’re not a suspension engineer in disguise?

I used to work for a company that ran a team in the BTCC and one of the perks of the job was free admission to race events, part of that gave limited access to the pit areas and I’ve had the opportunity to speak to race engineers about this kind of thing.

sucahyo
Just compare this video with my GT1 video and GT2 video. And see which has closer similarity. GT1 video show the same behaviour as Viper Racing car using soft spring and very stiff damper. GT2 video show the same behaviour as Viper Racing car using very stiff spring and soft damper.

I see this video a lot more similar to GT2 Supra video. Where stiff spring rate make the bouncing frequency high (fast bouncing) and soft damper make the bouncing last a bit longer.

I’m sorry but as you have totally avoided providing me with the full settings on the two Supra’s, and are just giving me ‘bumper’ cam videos to work with I’m not going to discuss this. How the hell am I meant to talk about this with out the settings and the opportunity to try them for myself?

sucahyo
And I am firmly believe if they reduce the spring rate stiffness, the trailing bounce will be reduced. If they increase the damper stiffness the trailing bounce will also be reduced. If they reduce the damper stiffness the trailing bounce will be increased. If they use an very stiff damper to the point it overpowering the spring rate, the trailing bounce will not happen, but instead the very jerky, jumpy movement happen, and I think in every bump it will be in danger of loosing control.

Oh my goodness you actually just made me spit coffee all over my desk.

From a few scant minutes of TV footage and without any knowledge of the cars, track or access to telemetry data you have decided that the BTCC engineers who set the cars up are wrong!!!!!!!!

A few points here for you, first if they reduced the spring rates the cars would run the risk of bottoming out, meaning they would have to run higher ride heights, which would raise the COG, which would reduce overall cornering speeds and grip levels. Nice piece of advise.

Secondly what you are seeing there is very well controlled suspension movements, Birmingham was easily the fastest circuit that the BTCC ever used, as well as the bumpiest. This was also the days of the Super Tourer class, capable of very high speeds. I’m sure that you are aware that the force of a bump (roughly) increases by a factor of four as speed doubles. Given the speeds involved here the very bumpy nature of the public roads that the Birmingham city circuit (this is not a closed race track, rather a city street circuit), you are going to see some bounce. It’s either that or loose control. The videos you picked probably shows the softest damper setting the BTCC would ever have used, but that does not make them ‘soft’ and certainly still a long way removed from road car dampers.

sucahyo
Just to provide a more complete setting option like usually available when tuning race car.

So you are saying that they wanted to give race car range of settings, but this is not meant to represent race suspension. Then why does both the ‘ticker’ on GT4 and the official guide clearly imply that it is race suspension? Why would PD not give us the option to fit race suspension when we can fit ‘race’ parts in every other area of the car? Or do you thing that being able to change the gear ratios in the way we can in the FC Gearbox is not meant to represent a racing gearbox? What about the FC LSD?

sucahyo
Trying to immitate the level of detail included when tuning car. But I have no clue why they only included stabilizer in the most expensive upgrade. And besides, isn't single adjustable damper in real life only provide damper rebound adjusment? And yet PD provide both bound and rebound connected together.

The level of detail included in the FC suspension set-up is still a long way off the adjustments that can be provided in motorsport, but its also a fair way from what can be commonly carried out on the average street car.

Your point on dampers is also a bit strange; dampers are adjustable in may ways when bought as aftermarket items, it very much depends on application and price. Yes most of the cheaper end of the adjustable damper scale is single adjustment and that is normally on the rebound only. However real world race dampers will often allow you to adjust far more than just bound and rebound, the GT series simplifies this, but that does not mean that it’s not meant to replicate a race set-up.

sucahyo
Don't know, maybe change of mind. They provide more range, from very soft to very stiff damper in GT1, and provide very soft to soft damper in GT2 and GT4.

Or just maybe you’re wrong.

sucahyo
Sure, but telling the difference in my dad's car tire & suspension noise when using different damper is very easy. Quieter sound when using new damper, from very harsh to more calm, from brrrrrrush to bapbapbap.

And I’ve said without any way to back this up its irrelevant.

sucahyo
If you really think that stiffer damper is not the only cause of increased vibration and produce a harsher sound what you say should be:

"GT is obviously far simpler, and from my testing (all other factors being equal) as you increase or reduce the damper stiffness the sound and feel gets harsher depend on wether current damper is too stiff or too soft."

Italic part added.

No. Why should I, I did not say that damper adjustment was the only cause of increased vibration and noise.

Lets be quite clear here sucahyo, I did not say what you are trying to make out at all. Stop implying it right now; it’s both incorrect and misleading. Its also a diversion, and an un-need one at that.

sucahyo
When you say:
"GT is obviously far simpler, and from my testing (all other factors being equal) as you increase the damper stiffness the sound and feel gets harsher."

You already make an assumption that current damper is already stiff. How do you decide this? I hope this is not chicken and egg situation.

No I don’t at all. Please stop telling me what I am assuming, it’s rather presumptuous, not to mention bloody rude. Ask me to clarify by all means, but do not tell me what I meant to say.

Did you miss the ‘all other factors being equal’ part, or just ignore it, or maybe not understand it.

sucahyo
And you still don't answer:
"And do you not notice how easily we can reduce car jumpiness in GT4 by reducing spring rate?"

I don’t recall seing it in the first place and utterly fail to see what relevance it has? Have I ever said otherwise? No.

sucahyo
Are you still interested to do test in another game?

When I have the time (it is close to Christmas after all) and providing it does not mean having to install anything else, I already have everything I want/need.

sucahyo
I use the quote to show you that in GT4 you see soft damper behaviour, not stiff. Something that you even said it yourself (wallow). It's to answer your post:
"And nor do the cars in GT4 feel 'boeing, boeing' with high damper settings, GT4's damper settings do not allow you to set truly soft values (not as represented by every other sim in the last list I posted."

Utter and complete rubbish. I said that the wallow on lower damper values was greater than that on higher damper settings. Plain and simple, I even clarified it for you. I have never once said that a high damper setting will always stop all wallowing on every car (go on try and find me saying it).

If all other factors are equal, and higher damper values reduce the level of wallowing they are firmer.

Your assumptive nature is getting quite annoying, its does not help your side of the discussion and looks rather childish. Simply put you are once again clutching at straws here to try and prop up a point that is falling down around you.

You are also increasingly trying to manipulate my words and pick up on what you see as 'incomplete' statements, for example the entire dampers and harshness, because I did not specifically say that other factors can cause these thing you have try to make out that I said they were the only cause. I will not stand for this under any circumstances, its miss-leading plain and simple. Do it one more time and I will ask another mod to look over it.

Regards

Scaff

sucahyo · Dec 22, 2006

Scaff
What are you talking about, I asked why you said that PD had modelled faulty dampers in GT4 and you come back with some nonsense about manufacturers? This is the FC suspension upgrade we are talking about here, it is meant to represent a full replacement of the stock suspension system with one that is tuned for motorsport use.

I think that even when PD use "faulty" damper (I will call this overly soft damper next), they can still mimic the behaviour of race car, even if it's limited to race car with very stiff damper and soft damper.

I use the term soft damper for condition when the spring strength overpowering the damper strength. Too soft damper for condition when it can make the car jumpy or wallowy.

I consider the spring strength and damper strength as equal when the suspension will revert back to it's original position, after got moved by bump, fast enough and without overshoot or do cycle.

About faulty, I think I will stop calling an overly soft damper behaviour (like what happen with my dad's car previous damper) as faulty damper. Yesterday, I follow a fairly new Hyundai Atoz GLS Vaj (6 moths old according to license plate). It has worse rear damper than my dad's car previous damper. Our speed is about 60mph. On low frequency road irregularity (rather flat multiple bump), it bounce few times before settle down. On high frequency road irregularity (rather spiky multiple bump), the tire/suspension made a loud durrrrp sound and making very fast up and down movement, make the car rear jump upward sometimes. The driver is still young and seem not bothered with it as he still going at about 60mph. As we pass high frequency road irregularity few times, the rear suspension behaviour is still the same.

Since even a new car can have an overly soft behaviour, I will stop calling those damper behaviour as faulty one. I mean, how come new car equipped with faulty damper?

Scaff
Having driven the Elise a number of times, even on the default settings I cant recall any oscillation at all.

I believe that jiggle in Elise is the result of tire osccilation.

Scaff
I mean it looks a little like bouncing from under-damping, but its not. Do you not even have access to a PC that will let you view these, because its rather difficult to run around trying to find videos that you can watch when so many are easily available on youtube.

I got a lot of disconnection, even with an hour of waiting I can only watch the first few second.

Scaff
There we go, they are quite big (for dial-up) at 20-25meg each. They focus on the Alfa 155 in Touring Car form, but also include a lot of BTCC footage.

Thanks, I can watch the video.

Still see some small bouncing, small up and down movement after passing the bump. The car has much less bouncing than Birmingham video. But the car still bouncing.

Still has the same conclusion, BTCC car jumpy because spring rate overpowering damper strength. not the opposite.

Sure maybe it's damper has much more stiffness than road car damper, but since damper do not overpower spring strength, I still call it soft.

If the car bounce only one after bump, and the tire go back to it's original position quickly. I call it damper match the spring strength.

If the car show jerky, sudden elevation change without the sign of bounce, or the tire go back to it's original position slowly, I call it damper overpowering spring strength.

Scaff
Im sorry but as you have totally avoided providing me with the full settings on the two Supras, and are just giving me bumper cam videos to work with Im not going to discuss this. How the hell am I meant to talk about this with out the settings and the opportunity to try them for myself?

Ok, ok, I will provide you with full setting. It's not like any other setting gonna make a difference anyway. I already provide you with enough setting to simulate the same thing, the setting that I still don't post is toe and camber. So here it is:

Test done by bumper view.

Stock GT1 Toyota Supra RZ + FC suspension, set A:
-Spring Rate: 12.9 / 6.1
-Ride Height: 130 / 130
-Damper: 10 / 10
-Camber: 2.0 / 1.0

Stock GT1 Toyota Supra RZ + FC suspension, set B:
-Spring Rate: 7.6 / 3.6
-Ride Height: 130 / 130
-Damper: 10 / 10
-Camber: 2.0 / 1.0

Both set A and B make the car do jerky jumpy movement, I try using different ride height and camber and still get the same result so:

Stock GT1 Toyota Supra RZ + FC suspension, set C:
-Spring Rate: whatever
-Ride Height: whatever2
-Damper: 10 / 10
-Camber: whatever

Set C will make the car do jerky sudden jumpy movement.

Stock GT1 Toyota Supra RZ + FC suspension, set D:
-Spring Rate: 12.9/6.1
-Ride Height: 130/130
-Damper: 2 / 2
-Camber: 2.0/1.0

Set D show bouncy jumpy movement, not jerky or sudden.

Stock GT2 Toyota Supra RZ + FC suspension, set W:
-Spring Rate: 20.0 / 20.0
-Ride Height: 130 / 130
-Bound: 10 / 10
-Rebound: 10 / 10
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 3 / 3

Stock GT2 Toyota Supra RZ + FC suspension, set X:
-Spring Rate: 20.0 / 20.0
-Ride Height: 130 / 130
-Bound: 1 / 1
-Rebound: 1 / 1
-Camber: 2.0 / 1.0
-Toe: 0 / 0
-Stabilizers: 3 / 3

Both set W and X make the car do bouncy jumpy movement, I try using different ride height, camber, toe and stabilizer and still get the same result so:

Stock GT2 Toyota Supra RZ + FC suspension, set Y:
-Spring Rate: 20.0 / 20.0
-Ride Height: whatever
-Bound: whatever
-Rebound: whatever
-Camber: whatever
-Toe: whatever
-Stabilizers: whatever

Set Y will make the car do bouncy movement.

Stock GT2 Toyota Supra RZ + FC suspension, set Z:
-Spring Rate: 5.0 / 5.0
-Ride Height: 130/130
-Bound: 1/1
-Rebound: 1/1
-Camber: 2.0/1.0
-Toe: 0/0
-Stabilizers: 3/3

Set Z show less bouncy movement compare to set Y.

If needed I can post other suspension seting variation that I test too. Even though I personally think set C and set Y is enough.

This experiment conclution:
- The jumpy behaviour in GT1 is jerky and sudden. The main cause of this behaviour is damper. By using damper 10 the car will show jerky and sudden movement. By using damper 2 the car will show bouncy movement instead.
- The jumpy behaviour in GT2 is bouncy. The main cause of this behaviour is spring rate. By using spring rate 20.0 the car will show bouncy movement. By using spring rate 5.0 the bouncy movement reduced much.
- Damper in GT1 can overpower spring rate strength. Damper in GT2 do not.
- Damper 10 in GT1 overpowering spring rate. Damper 10 in GT2 do not.
- Damper in GT1 can be soft and stiff. Damper in GT2 can only be soft.
- Since GT4 spring rate have so much influence in car jumpiness, changing damper do not change the jumpiness much, GT4 damper is soft.

Spring strength and damper strength have to be matched. When spring strength overpower damper strength, increasing damper stiffness will reduce the sound/feel/visual harshness. reducing damper stiffness will increase the sound/feel/visual harhsness.

Since increasing damper value in GT4 make the sound/feel/visual harsher, GT4 damper tuning is reversed.

Scaff
From a few scant minutes of TV footage and without any knowledge of the cars, track or access to telemetry data you have decided that the BTCC engineers who set the cars up are wrong!!!!!!!!

I never said they wrong. I just say what I think to reduce bounce. Just bouncing perpective. I am aware that they let it bounce for good reason. I am just saying to let you know that those bounce do not happen because damper strength overpowering spring strength. Those bouncing happen because spring strength overpowering damper strength. Bounce that you will see on max spring max damper GT2 and GT4. Not bounce that you will see on max spring max damper in GT1.

Scaff
Given the speeds involved here the very bumpy nature of the public roads that the Birmingham city circuit (this is not a closed race track, rather a city street circuit), you are going to see some bounce. Its either that or loose control. The videos you picked probably shows the softest damper setting the BTCC would ever have used, but that does not make them soft and certainly still a long way removed from road car dampers.

I will call the damper soft when damper do not overpower spring strength. So even when it has much more stiffness than road car damper, if it still do not overpower spring strength, I will call it soft.

I translate what Skip barber says as for bumpy ractracks expect more bounce:
"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."

I have no doubt that what you see in your Integra Type R Touring car can even happen when the damper is too soft. This car with the any damper values can display the same characteristic on encountering a curb as the BTCC car. Since damper strength in this car is already overpowerd by spring rate by much.

Scaff
So you are saying that they wanted to give race car range of settings, but this is not meant to represent race suspension. Then why does both the ticker on GT4 and the official guide clearly imply that it is race suspension? Why would PD not give us the option to fit race suspension when we can fit race parts in every other area of the car? Or do you thing that being able to change the gear ratios in the way we can in the FC Gearbox is not meant to represent a racing gearbox? What about the FC LSD?

If you are talking about the suspension stiffness, soft damper and very stiff spring rate range will be adequate to make your car look behave like race car. In other hand hard damper and soft spring rate make it hard to make your car look like road car. Just like what we see in GT1, using damper 10 on any car will not make it look behave like road car normally do (jerky sudden up and down).

Scaff
Yes most of the cheaper end of the adjustable damper scale is single adjustment and that is normally on the rebound only.

I am questioning the reason why PD use single adjustment to set both bound and rebound value, where it should be rebound value only. Hack material, I forget that many people may not know this. I don't know if you can really tell the difference when tuning, since detecting wether only rebound or both bound and rebound that change can be hard.

Scaff
No. Why should I, I did not say that damper adjustment was the only cause of increased vibration and noise.
...
Did you miss the all other factors being equal part, or just ignore it, or maybe not understand it.

No, I don't argue about "damper adjustment was the only cause of increased vibration and noise" at all. I asking why you ignoring the fact that reducing the stiffness of soft damper can also increase vibration and noise. And I think we both now that damper is not included in 'all other factors being equal'.

Scaff
Lets be quite clear here sucahyo, I did not say what you are trying to make out at all. Stop implying it right now; its both incorrect and misleading. Its also a diversion, and an un-need one at that.

It's sad that you still don't realize it.

If you want other mod to review my post about calling you inconsistent, allow them to review what I say bellow.

// start
From the same post:

Scaff
GT is obviously far simpler, and from my testing (all other factors being equal) as you increase the damper stiffness the sound and feel gets harsher.
...
No I have not, Ive said that stiffer dampers increase vibration and produce a harsher sound, not that they are the only cause of this.

"as you increase the damper stiffness the sound and feel gets harsher" only TRUE if damper currently overpowering spring strength. will be FALSE if spring currently overpowering damper strength. Since the sound and feel get harsher if both do not match/equal.

You say "not that they are the only cause of this" where you answer can only be TRUE when damper currently overpowering spring strength.

You obviously ignoring the possibility of too soft damper make the sound and feel harsh at the first statement.
// end

And I read the "all other factors being equal" part.

Scaff
I dont recall seing it in the first place and utterly fail to see what relevance it has? Have I ever said otherwise? No.

Your concluction from your many test would only be correct based on assumption that damper overpowering spring strength. When damper overpowering spring strength, increasing the damper stiffness more would make the problem worse, since both will be more unequal.

I see that GT4 spring overpowering damper strength. When spring overpowering damper strength, increasing damper stiffness would make the problem reduced, since both will be more equal.

My reason to see GT4 spring overpowering damper strength:
- changing damper value will not change jiggle visual, rumble feel, harsh sound as much as changing spring rate. Spring rate have much more influence in that, damper has much less influence, damper is weaker, damper is weak, damper is soft.
- you can see Subaru 360 wallow
- you can see Subaru 360 bouncing around
- you can see tire vibration in Caterham Fireblade
- you can see Lotus Elise still bouncing even after passing bump, it do not jump only at the bump.

Scaff
Utter and complete rubbish. I said that the wallow on lower damper values was greater than that on higher damper settings. Plain and simple, I even clarified it for you. I have never once said that a high damper setting will always stop all wallowing on every car (go on try and find me saying it).

No, what I am try to say is wallow happen because damper do not overpowering spring strength, so GT4 damper is soft.

Scaff · Dec 22, 2006

sucahyo
I think that even when PD use "faulty" damper (I will call this overly soft damper next), they can still mimic the behaviour of race car, even if it's limited to race car with very stiff damper and soft damper.

While I appreciate that you will now stop referring to them as 'faulty' dampers, I do have to as you to clarify the second part of the above quote it which you seem to be describing a car with very stiff and soft dampers at the same time? I can only think that this is a mis-type.

sucahyo
I use the term soft damper for condition when the spring strength overcoming the damper strength. Too soft damper for condition when it can make the car jumpy or wallowy.

Jumpy is not a quality I would use to describe soft dampers, rather one that I would us to describe stiff dampers, a car which has dampers unable to react quickly enough to the surface changes and as a result will suddenly and quickly 'jump'.

A greater tendency to wallow I would attribute to softer dampers and also a soft bouncy feel (not the same as the jumpy described above).

sucahyo
I consider the spring strength and damper strength as equal when the suspension will revert back to it's original position, after got moved by bump, fast enough and without overshoot or do cycle.

And may I ask do you believe that a car can be set to a 'perfect' damper set-up that will allow it to react in this way for every situation it encounters on a track?

What about road cars? They are often massively under-damped for the actual spring rates, as to do otherwise results in a ride almost no road car driver would live with.

Allan Staniforth
That excellent author and engineer Colin Campbell points out in his book Automobile Suspensions, that there is a mathematical Critical Damping Co-efficent we can all work out, not unexpectedly based on spring frequency and weight. But he has hardly spelled it out before having to qualify, that in real life road cars, the CDF needs hefty modification reducing it by 50% to 70% to approach any sort of acceptable ride

sucahyo
About faulty, I think I will stop calling an overly soft damper behaviour (like what happen with my dad's car previous damper) as faulty damper. Yesterday, I follow a fairly new Hyundai Atoz GLS Vaj (6 moths old according to license plate). It has worse rear damper than my dad's car previous damper. Our speed is about 60mph. On low frequency road irregularity (rather flat multiple bump), it bounce few times before settle down. On high frequency road irregularity (rather spiky multiple bump), the tire/suspension made a loud durrrrp sound and making very fast up and down movement, make the car rear jump upward sometimes. The driver is still young and seem not bothered with it as he still going at about 60mph. As we pass high frequency road irregularity few times, the rear suspension behaviour is still the same.

Unfortunately its not that straightforward to be able to say that about the bumps in question. As we have discussed many times dampers are velocity sensitive and as such the velocity the have to deal with is determined by the bumps (how many and how big and how close together) and the speed at which we travel over them.

For example (taken from Race and Rally Car source book)

Situation A - 50 x 1/4 inch bumps encountered in 1 second = velocity of 12.5in/sec

Situation B - 10 x 1 1/4 inch bumps encountered in 1 second = velocity of 12.5in/sec

Now these two situations would be 'identical' to a damper unit, but if we add the following

Situation A - 1 second for a Formula Ford travelling at 90mph covering 150ft of track

Situation B - 1 second for a sports car travelling at 45mph covering 75ft of average road.

Now these two situations involve exactly the same velocity being placed on the damper in the same time period, but they will feel very different indeed.

The point behind the above is that you can't just look at a car on the road and say it sounds/ looks (and you have nothing other than sound and visual info here - you don't know how it felt to drive) a certain way and then use that to state that a totally different car, in a totally different set of situations will react in the same way.

sucahyo
Since even a new car can have an overly soft behaviour, I will stop calling those damper behaviour as faulty one. I mean, how come new car equipped with faulty damper?

Well it possible, but unlikely. Do you not think that the point I raised above is far more likely (the one regarding CDF).

sucahyo
I believe that jiggle in Elise is the result of tire osccilation.

But the tyre can't be seen to be osccilating?

sucahyo
I got a lot of disconnection, even with an hour of waiting I can only watch the first few second.

Which is a shame as the first youtube clip (which is very short) quite clearly shows stiff damping as Gabriele Tarquini's Alfa hit a curb too fast and immediately jacks up onto two wheels and upto an angle of around 30degrees before returning to the ground. The clip clearly shows the cars return to the ground and not a hint of bounce or wallow is present in any way.

sucahyo
Still see some small bouncing, small up and down movement after passing the bump. The car has much less bouncing than Birmingham video. But the car still bouncing.

Still has the same conclusion, BTCC car jumpy because spring rate overcoming damper strength. not the opposite.

Sure maybe it's damper has much more stiffness than road car damper, but since damper do not overcome spring strength, I still call it soft.

If the car bounce only one after bump, and the tire go back to it's original position quickly. I call it damper match the spring strength.

If the car show jerky, sudden elevation change without the sign of bounce, or the tire go back to it's original position slowly, I call it damper overcoming spring strength.

First a point of clarification, when I talk about soft or firm damping I am always talking about it in relation to the spring rate. Any time I am comparing road vs track damping rates I have always clearly stated as much. You don't need to keep pointing this out.

Once again you are looking at this in a totally black and white manner. Dampers in the real world can not be set to deal with every corner and every bump, and having watched touring cars for over 20 years I have never seen or heard anything to suggest that they are softly damped

The teams will always aim to set the damping to the circuit but massively soft setups of the type you seem to be implying are not used.

sucahyo
Ok, ok, I will provide you with full setting. It's not like any other setting gonna make a difference anyway. I already provide you with enough setting to simulate the same thing, the setting that I still don't post is toe and camber. So here it is:

Test done by bumper view.

Thanks, now I have something to work with and test, I'm not sure however why the test was done with bumper cam only?

sucahyo
Spring strength and damper strength have to be matched. When spring strength overcome damper strength, increasing damper stiffness will reduce the sound/feel/visual harshness. reducing damper stiffness will increase the sound/feel/visual harhsness.

Says who? Almost every road car ever made has dampers that are 'soft' for the springs fitted (remember the bit on CDF), yet when we fit firmer dampers to road cars the ride gets harder and the harshness will increase. For what you are saying to be true the springs would have to be the principal factor is determining ride quality, and while its true to say they have a part to play, they are not the dominate factor, dampers are.

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.

(BTW - The Elise's proble, is the last one of these - not wheel oscillation)

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.

sucahyo
Since increasing damper value in GT4 make the sound/feel/visual harsher, GT4 damper tuning is reversed.

Nope.

sucahyo
I translate what Skip barber says as for bumpy ractracks expect more bounce:
"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."

Really, could you highlight the part where he says bounce?

sucahyo
I have no doubt that what you see in your Integra Type R Touring car can even happen when the damper is too soft. This car with the any damper values can display the same characteristic on encountering a curb as the BTCC car. Since damper strength in this car is already overcomed by spring rate by much.

That's funny because I can recall you saying you could not run these tests and you could not drive accurately enough. Have you re-run them?

I ask because I carried out this test many, many times and I can quite clearly recall saying (over and over again) that this can happen with soft dampers, but it is more likely to happen with stiffer dampers as they are less able to react to the curb on impact. The test I put together quite clearly shows that.

sucahyo
I am questioning the reason why PD use single adjustment to set both bound and rebound value, where it should be rebound value only. Hack material, I forget that many people may not know this. I don't know if you can really tell the difference when tuning, since detecting wether only rebound or both bound and rebound that change can be hard.

Because GT4 isn't perfect.

sucahyo
No, I don't argue about "damper adjustment was the only cause of increased vibration and noise" at all. I asking why you ignoring the fact that reducing the stiffness of soft damper can also increase vibration and noise. And I think we both now that damper is not included in 'all other factors being equal'.

I don't ignore it at all I am quite clearly saying that as long as all other factors remain the same (same car, same bump, same speed, all other settings the same) then firmer dampers increase harshness, firm up the ride and increase vibration.

Dampers are the principal tool in controlling this:

Stasis Engineering
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.

Source - http://www.stasisengineering.com/faq.aspx

I have not changed my mind in this or been unclear at any point. In GT4 as you increase damper levels/strength/stiffness/firmness (call it what you want) then harshness (in feel and noise) increase and the cars ride gets harder.

sucahyo
It's sad that you still don't realize it.

Don't realise what?

That you are attempting to make out I said something I did not, the above should be clear enough for you now I hope.

sucahyo
Your concluction from your many test would only be correct based on assumption that damper overcoming spring strength. When damper overcoming spring strength, increasing the damper stiffness more would make the problem worse, since both will be more unequal.

My conclusions from all my tests are quite clear and documented, they based on the settings used at the time. Sucahyo its you that has played 'fast and loose' with the detail and settings used in tests, not me.

BTW - I don't know if you have noticed by the results of the Caterham test have/are being posted up.

https://www.gtplanet.net/forum/showthread.php?t=89742

Regards

Scaff

sucahyo · Dec 26, 2006

Scaff
While I appreciate that you will now stop referring to them as 'faulty' dampers, I do have to as you to clarify the second part of the above quote it which you seem to be describing a car with very stiff and soft dampers at the same time? I can only think that this is a mis-type.

Yes, it is a mis-type. I mean very stiff spring and soft damper.

Scaff
And may I ask do you believe that a car can be set to a 'perfect' damper set-up that will allow it to react in this way for every situation it encounters on a track?

No, I just say what I think as equal power damper and spring, not related to perfect handling or perfect ride. I am aware that there is many experiment about active damping.

Scaff
What about road cars? They are often massively under-damped for the actual spring rates, as to do otherwise results in a ride almost no road car driver would live with.

And much softer than massively under damped for actual spring rate will also result in a ride almost no road car driver would live with, he could die too.

Scaff
Unfortunately its not that straightforward to be able to say that about the bumps in question. As we have discussed many times dampers are velocity sensitive and as such the velocity the have to deal with is determined by the bumps (how many and how big and how close together) and the speed at which we travel over them.

I guess you can understand what I mean better with picture:

Low frequency bump, road irregularity where I have handling problem driving my dad's car with original suspension.

Low frequency bump, where Hyundai Atoz GLS Vaj show plenty of bouncing, this is main road so most car pass it at above 70kmph.

High frequency bump, where my dad's car with original damper would make a lot of mechanical noises, much quieter with new stiffer damper, showing the same car model:

Other type of high fequency bump, same bump type with the one that make Hyundai Atoz GLS Vaj tire move up and down violently:

The last bump of series of bump that make the Hyundai Atoz GLS Vaj rear lift, car in the photo pass at about 100kmph:

Big bump, where car with insufficient damper will show bad jump. the picture show car that do nice jump (at about 70kmph), where the driver should feel more comfortable than the driver of car with very soft damper:

What is the correct term that I should use for previous kind of bump?

Scaff
The point behind the above is that you can't just look at a car on the road and say it sounooks (and you have nothing other than sound and visual info here - you don't know how it felt to drive) a certain way and then use that to state that a totally different car, in a totally different set of situations will react in the same way.

Well it possible, but unlikely. Do you not think that the point I raised above is far more likely (the one regarding CDF).

I follow the car closely at about 2 meter distance, and I can see the driver got lifted from the chair when the car rear lifted, and see his shoulder shaking up and down when the tire vibrate. Those ride is uncomfortable and dangerous. If the driver can know what actually happen with his rear tire, maybe he will slowed down. I see another Hyundai Atoz GLS yesterday, but too bad he turn before I got the chance to get the picture of it in action, but I manage to see his rear tire do a little up and down vibration when doing cornering (about 70kmph).

Scaff
But the tyre caa't be seen to be osccilating?

You can see the same kind of tire up and down vibration as I see in Hyundai Atoz GLS, and what I mean by loosing traction because the tire vibrate too much by seeing B-Spec driving fully tuned R5 tire Subaru 360 in Autumn Ring:
-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

Scaff
Which is a shame as the first youtube clip (which is very short) quite clearly shows stiff damping as Gabriele Tarquini's Alfa hit a curb too fast and immediately jacks up onto two wheels and upto an angle of around 30degrees before returning to the ground. The clip clearly shows the cars return to the ground and not a hint of bounce or wallow is present in any way.

I see. Your first Alfa Romeo 155 BTCC video also show car dropped from maybe 30cm height. This remind me of my car jump test in GT2 where car with lower damper value bounce less.

In my opinion, the car do not bounce because it's high speed damper strength is equal or overpoweing spring rate strength.

This remind me to what you say previously:
"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."

Can you please explain it again in relation with no bounce when the car return to the ground?

Scaff
Thanks, now I have something to work with and test, I'm not sure however why the test was done with bumper cam only?

I can see the car unstability / up and down movement clearly when using bumper view. It still can be seen on other view.

Scaff
Says who? Almost every road car ever made has dampers that are 'soft' for the springs fitted (remember the bit on CDF), yet when we fit firmer dampers to road cars the ride gets harder and the harshness will increase. For what you are saying to be true the springs would have to be the principal factor is determining ride quality, and while its true to say they have a part to play, they are not the dominate factor, dampers are.

I am sorry, wrong choice of word, I thought the word harsh is what we use when we feel uncomfortable beecause of vibration or up-down shake.

Scaff
The following is taken from a Penske Technical Manual.
...
or we could take a look at Allan Stainforth (from Race and Rally car source book).

They both don't mention how my father car ride more comfortable and less noisy on high frequency bump (bump in photo I post above) when using stiffer damper. And not explaining how Hyundai Atoz GLS soft damper can be really dangerous when doing braking or turning in high road irregularity. But I guess they don't have this kind of problem when dealing with race car damper.

Scaff
Really, could you highlight the part where he says bounce?

No, just conclution. Smooth track = equal damper = no bounce, bumpy race track = softer damper = more bounce.

Scaff
I ask because I carried out this test many, many times and I can quite clearly recall saying (over and over again) that this can happen with soft dampers, but it is more likely to happen with stiffer dampers as they are less able to react to the curb on impact. The test I put together quite clearly shows that.

Maybe because what I see on the street loose traction is caused by soft damper, since I usually see the car loose contact with the road because the tire move up and down too much.

Scaff
I don't ignore it at all I am quite clearly saying that as long as all other factors remain the same (same car, same bump, same speed, all other settings the same) then firmer dampers increase harshness, firm up the ride and increase vibration.

I said it too before, but I mention this for occasion where damper strength over powered spring strength by much. And I think they advise it on occasion where damper strength is still weaker than spring strength. I am sorry, but it seems I miss it, which reference say exactly that firmer damper increase vibration and sound harshness?.

Scaff · Dec 26, 2006

sucahyo
Yes, it is a mis-type. I mean very stiff spring and soft damper.

Thank you. So now we have finaly got to it you are saying that PD coded GT4 so that we could only recreate race cars with stiff spring set-ups and soft dampers.

Why?

That makes no sense at all, particularly as the move to higher damper values as you upgrade the suspension would still have PD saying that as we stiffen all other areas of the car, as a default we will give you softer dampers. That make no sense at all.

sucahyo
No, I just say what I think as equal power damper and spring, not related to perfect handling or perfect ride. I am aware that there is many experiment about active damping.

Congratulations, another sentence that makes little or no sense at all.

sucahyo
And much softer than massively under damped for actual spring rate will also result in a ride almost no road car driver would live with, he could die too.

Quite right, but thats totally different to saying it would feel just as harsh as an over-damped car. Quite simply it would not, unless the lack of damping allowed the springs or dampers to bottom out and hit the bumps stops, but as discussed previously thats not a soft set-up anymore, but a very, very stiff one.

Please remember that its this level of chronic under-damping that you are implying GT4 allows us to set on race cars!!!!!

sucahyo
I guess you can understand what I mean better with picture:

***SNIP***

What is the correct term that I should use for previous kind of bump?

I understand exactly what you are trying to say, I dont need the pictures, you are failing to understand what I am saying.

Dampers are velocity dependent and while the bump frequency plays a part in that, there are other factors that need to come into play as well. You cant just look at a bump and say that because car X looks like so when it goes over it, then car Y will react the say going over a different bump at a different speed.

sucahyo
You can see the same kind of tire up and down vibration as I see in Hyundai Atoz GLS, and what I mean by loosing traction because the tire vibrate too much by seeing B-Spec driving fully tuned R5 tire Subaru 360 in Autumn Ring:
-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

See this is exactly what I am talking about. Are the Hyundai Atoz and Subaru 360 the same car? No of course they are not. Is the Autumn Ring a perfect recreation of the road in your picture? No of course its not.

As a like for like comparison this is useless for two reasons, the first are the wildly differing factors outlined above, the second is even more fundamental in that no one else saw the Atoz in question!!!!!!!

sucahyo
I see. Your first Alfa Romeo 155 BTCC video also show car dropped from maybe 30cm height. This remind me of my car jump test in GT2 where car with lower damper value bounce less.

In my opinion, the car do not bounce because it's high speed damper strength is equal or overpoweing spring rate strength.

This gets better and better. Now you are saying that the Alfa BTCC team set the cars up with over-damped high speed dampers to make sure the cars cause as much of a problem over curbs as possible. So let me get this straight, you are saying that Alfa set these cars up to be under-damped in low-velocity damping to make sure the cars bounce and roll under control situations (cornering, etc) and over-damped in high-velocity damping? Its a bloody wonder these guys ever managed to win anything, let alone the BTCC and ETCC championships, what did they ever do without you.

That explanation is quite simply daft, it also flies in the face of the solution that Volvo came up with in later years of the BTCC, involving very stiff suspension set-ups for control of the car and softer suspension set-up for the curbs. Yes the following piece does talk about spring rates, but it does also indicate a desire for stiff set-ups for the majority of situations the car encounters and softer set-ups to deal with the curbs and big bumps.

The most impressive example of dual-rate suspension magic that I have ever seen was hidden away in the front wheelwell of a BTCC Volvo S40. Built and campaigned by TWR until this year, the front suspension on the car I saw used a spring rate that actually got softer as the suspension was compressed. How? The tender spring was pre-compressed; held in partial compression with a simple tethered spring perch. Let's say that the front spring would see a maximum of 1000 lbs during normal competition driving. With the tender spring pre-compressed to 1000 lbs, it didn't move at all in normal driving. But hit a curb, as BTCC cars do when their drivers get aggressive, and the force would be enough to get both springs involved. Suddenly, with two stacked springs working together, the suspension would go soft and suck up the impact of the curb. With cars often going three wide, fender to fender for several laps at a time, being able to hop curbs at will could be a serious advantage.

Source - http://www.sportcompactcarweb.com/editors/technobabble/0011scc_technobabble/

sucahyo
This remind me to what you say previously:
"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."

Can you please explain it again in relation with no bounce when the car return to the ground?

The car returns to the ground and the suspension deals with as much of it as it can, the rest being transferred to the car, mainly through the point were the top of the strut meets the car structure. BTCC cars commonly have strut mounting points for the roll-cage and as such the car is almost certainly capable of absorbing the force in question (and it was a slow drop from more than 30cms). A road car in the same situation would certainly be quite different, having no roll cage (99% of road cars anyway) to strengthen this point, its quite possible that the suspension strut itself could be forced through the mounting point (the area shown in the picture below), this kind of damage I have seen on a number of occasions.

sucahyo
I am sorry, wrong choice of word, I thought the word harsh is what we use when we feel uncomfortable beecause of vibration or up-down shake.

It does, the word harsh is not the problem, your understanding of the subject is.

sucahyo
They both don't mention how my father car ride more comfortable and less noisy on high frequency bump (bump in photo I post above) when using stiffer damper. And not explaining how Hyundai Atoz GLS soft damper can be really dangerous when doing braking or turning in high road irregularity. But I guess they don't have this kind of problem when dealing with race car damper.

First of all you have not shown that your fathers car was fitted with a stiffer damper at all, from what you have described so far it sounds far more likely that a faulty or damaged damper was replaced. Until you can show some definitive proof to the contrary please stop using it as an example.

sucahyo
No, just conclution. Smooth track = equal damper = no bounce, bumpy race track = softer damper = more bounce.

And a wrong conclusion at that. Im sorry but that piece read quite clearly to me (particularly when taken in context with everything else the book in question says on dampers 0 much of which has been posted here) that damper settings that are too firm for the track will result in a loss of contact with the track surface and as a solution softer damper settings should be used.

sucahyo
Maybe because what I see on the street loose traction is caused by soft damper, since I usually see the car loose contact with the road because the tire move up and down too much.

And once again can you show this to anyone?

Until you can its rather useless as a working example, Ive provided you with video links, youtube links and experiments that can be easily run in GT4. You in turn provide garbled descriptions of what you told you dad to do, then tall stories that imply you did the work, then a retraction, then more great real world examples from rough roads and an attempt to directly compare them with on track behaviour.

sucahyo
I said it too before, but I mention this for occasion where damper strength over powered spring strength by much. And I think they advise it on occasion where damper strength is still weaker than spring strength. I am sorry, but it seems I miss it, which reference say exactly that firmer damper increase vibration and sound harshness?.

What are you talking about, how could you miss it.

Oh well here we go again

First we had this..

Scaff
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.

and this was posted straight after it.

Scaff
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.

and then later on in the same post there was this..

Scaff
Stasis Engineering

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.

Click to expand...

Source - http://www.stasisengineering.com/faq.aspx

.now each of those three talks quite plainly about dampers not only being the dominant factor in ride quality and harness, but also how in general terms as dampers stiffen and are more resistant the harness grows and ride quality gets firmer.

Now dont start with your silly games again that the exact words you are looking for are not present, that was a stupid demand the first time you made it and Im certainly not going to stand for it a second time. Not to mention that NVH factors (Noise Vibration and Harshness) are all masked through sound proofing and other means in road cars.

Regards

Scaff

Famine · Dec 27, 2006

I've been keeping my indigo eyes on this thread and I'd like to just ask a question - of you, sucahyo, if I may.

I will freely admit to not being the most car-tech-savvy person on Earth - though I am a physics geek. So I'd like you to tell me, if you can, what your understanding of how dampers work, and what it is they are supposed to do.

Feel free to be as expansive as you wish - but I'd like it in your own words, without any external supporting documents. Just the contents of your head with regards to what dampers do and how they do it.

Though I appreciate your efforts in this matter in advance, I'd like you to be as consistent as possible with your language - I think some of the issues we've seen arising in this thread come from ambiguity in language, and I'd like to avoid that if possible. I do understand that it's not your first language and it's to your credit that you communicate well in it.

Thank you.

sucahyo · Dec 28, 2006

Suspension do not have to be bottomed out to be feel uncomfortable using very soft damper.

Some reference about comfort vs handling which may help:
From University of Oulu - The improvement of full vehicle semi-active suspension through kinematical model, by Jukka-Pekka and Hyvärinen

the spring-mass mode from zero frequency up to the natural frequency of the sprung mass i.e. the first peak in the “ride damper”-frequency response curves. In this region, both comfort and road holding capabilities are improved with the “handling” damper, i.e. they are both superior compared to results achieved with a softer “ride” damper.
Regular ride between the resonance peaks of the system. In this region, both of the criteria are improved with a softer damping setting. The human body is most sensitive to the vibrations at this frequency range.
Wheel hop around the natural frequency of the wheel. Handling is improved in this region with a stiffer damper. The comfort suffers a minor penalty with the stiffer damping setting. This second peak at the wheel hop frequency is relatively well damped because of the relatively good damping characteristics of tires used in this vehicle model. With passenger cars, also comfort is usually improved a bit with the stiffer damper setting. Poor damping at this frequency range has a severe influence to the driving characteristics on rough roads. Rhythmic corrugations in crushed-rock roads are generated on this wheel hop frequency.
Harshness above wheel hop frequency. At this region most of the vibrations are absorbed by deflection of the tire. Also rubber bushings in the joints of the suspension links and the elastic fixtures of the damper suppress these high frequency vibrations if a real vehicle is considered. In this region, a softer damper shows improved comfort, while a minor penalty in road holding is suffered.

About damper is velocity dependent thing, I measure it relative with other car. When I follow Hyundai Atoz GLS, there is also other car moving at the same speed. On bump where Hyundai Atoz GLS has problem, those car do not.

If you never see Hyundai Atoz GLS maybe you can notice other car that show bouncy behaviour, see how it's tire behave on successive bump. Maybe an old Civic or Lancer.

About Subaru 360 vs Hyundai Atoz, I only want to let you know that fast tire up and down movement in Hyundai Atoz GLS is so much alike to the one that happen on Subaru 360.

About BTCC Alfa, I don't think damper choice is the only thing that decide winning. Besides, I think they use it for some good reason. From your second video, I see Alfa has stiffer damper than Ford Mondeo (bouncy at 4:15). The Alfa inside tire lift longer than other car on corner bump (1:40, 12:00 both car, 12:18, 15:30).

About vibration and sound harshness. Harsh in your reference refer to harsh ride which I assume would be the result of hard feeling, every bump send to the backbone kind of harsh. But I don't see explanation about vibration of tire or vibration of car body will be increase when using stiffer damper.

When I say vibration before, I mean:
- very soft damper vibration is caused by body or tire vibration
- very stiff damper vibration caused by car trying to follow road bump closely the same way as square brick would go through it.

And more important than vibration, no explanation about increase of damper stiffness make more suspension noises. On small succesive bump, my bike broken damper makes more noises than the new one. My dad's car original damper makes more noises than the new one.

When the car still wallow and the noise is reduced when we increase the damper value, it could only mean damper tuning is reversed.

Famine, it seems that I have to use other people graph at least. Image hosted by imageshack.us.

In a car, spring and damper will act as medium between tire and car body. Any movement, shock, vibrations or oscillations from the tire must go through spring and damper, and any movement, shock, vibrations or oscillations from the car body must go through spring and damper too. Aside from isolating tire and car body, spring also have job to support the car weight.

Spring can store energy, as elastic potential energy. It will try to return any force it receive, trying to maintain it's shape.
Damper can dissipate energy. It will try to absorb any force it receive by creating friction and convert it to heat. A hydroulic damper create friction by forcing fluid to flow through small valve. To avoid creating any elasticity power in damper, an ideal damper need to use an incompressible liquid, like oil or high compressed gas.

Without damper, spring will try to continue making the car body or tire oscillating. It's damper job to stop those oscillation. When the tire get moved up by bump, spring will try to oppose it with it's elastic power (trying to maintain it's previous shape) and damper will try to stop suspension movement with it's friction.

Stiffer spring has more elasticity power, can store more energy, which make it able to return more energy too. Stiffer damper has more friction, can dissipate more energy.

Damper is velocity sensitive, the faster it has to work, the higher it's friction. To control the damper rate at different suspension travel velocity, manufacturer provide us with low speed damping adjustment and high speed damping adjustment.

http://img19.imageshack.us/img19/5091/increaselowspeeddampings8ch.jpg

The speed of the suspension movement can depend on how fast the tire move up by the bump, the frequency of the tire oscillation after passing the bump, or the frequency of car body oscillation.

When an object attached to spring, it's osccilation frequency will depend on it's weight and spring stiffness. Stiffer the spring will have higher oscillation frequency. Heavier object will have lower oscillation frequency.

If we use guitar as an example. Thin string will produce higher sound frequency than thick string, it move faster. When you increase it's tension, it will produce higher sound frequency. To simulate how damper work put the guitar under water. The sound will mute faster and produce lower sound frequency.

In the same way, rubber string in air will produce higher sound frequency and make sound longer than when under water. Also, if the rubber string tension is low enough, we can see it move slowly before it go back to original position.

Since tire has much lower weight than car body, the suspension movement speed caused by tire oscillation is much higher than what caused by car body. Same spring that can make car body oscillate slowly can make tire oscillate very fast. And since damper is velocity sensitive, we can see damper has more effect on tire oscillation than car body oscillation.

Famine · Dec 28, 2006

Okay, I think I see where the problem is now.

This time in your own words and without using external references (like I said the first time), please tell me the difference between the bound and rebound sides of a damper/shock absorber.

Scaff · Dec 28, 2006

sucahyo
Suspension do not have to be bottomed out to be feel uncomfortable using very soft damper.

Some reference about comfort vs handling which may help:
From University of Oulu - The improvement of full vehicle semi-active suspension through kinematical model, by Jukka-Pekka and Hyvärinen

the spring-mass mode from zero frequency up to the natural frequency of the sprung mass i.e. the first peak in the ride damper-frequency response curves. In this region, both comfort and road holding capabilities are improved with the handling damper, i.e. they are both superior compared to results achieved with a softer ride damper.

Regular ride between the resonance peaks of the system. In this region, both of the criteria are improved with a softer damping setting. The human body is most sensitive to the vibrations at this frequency range.

Wheel hop around the natural frequency of the wheel. Handling is improved in this region with a stiffer damper. The comfort suffers a minor penalty with the stiffer damping setting. This second peak at the wheel hop frequency is relatively well damped because of the relatively good damping characteristics of tires used in this vehicle model. With passenger cars, also comfort is usually improved a bit with the stiffer damper setting. Poor damping at this frequency range has a severe influence to the driving characteristics on rough roads. Rhythmic corrugations in crushed-rock roads are generated on this wheel hop frequency.

Harshness above wheel hop frequency. At this region most of the vibrations are absorbed by deflection of the tire. Also rubber bushings in the joints of the suspension links and the elastic fixtures of the damper suppress these high frequency vibrations if a real vehicle is considered. In this region, a softer damper shows improved comfort, while a minor penalty in road holding is suffered.

Do you really want to get into this one?

OK well first off a couple of things about the paper you linked too above (which I seriously doubt you have fully read and understood), its not based on real world data, but rather computer modelling of possible reaction. Secondly its talking about the semi-active Skyhook suspension system (mainly used by Maserrati) and being Semi-active does cause a few issues for direct comparison. Its also a paper looking at its theoretical application to military off-road vehicles!!!!! In addition it freely admits that one of the main areas of NVH (Noise Vibration & harshness) reduction, that of using rubber bushings, etc is excluded because of the increased complexity it adds.

What it does confirm is that dampers are a critical factor in harshness and ride comfort (which you have previously disputed) and that generally harshness and ride firmness both increase as dampers are stiffened. What it adds (and you seem to have missed) is that human beings are more sensitive to particular frequencies of vibration, etc. So what is uncomfortable for a person at damper value x may well feel more comfortable with a slightly lower or higher damper value, that does not mean that harshness has not increased with a higher value, just that this increase in harshness is more comfortable.

We also would need to start to breakdown ride itself into primary and secondary. Lower frequency (around 30Hz) bumps/imperfections) are primarily dealt with by the springs and dampers and is the primary ride, higher frequency (300 to 1000Hz typically) bumps/imperfections are dealt with primarily by the sidewall compliance of the tyres and suspension and sub-frame mounting bushes. So if we took a S Class Merc and fitted very low profile tyres to it and replaced all the rubber bushing with solid mountings or bearing joints it would have almost no effect on NVH if we drove slowly over a speed hump, however if we then hit a small expansion joint at motorway speeds it would feel like our spines were being removed.

As you can see its no were near as simple as you want it to be, its also another of your massive distractions as it has little to nothing to add to the situation with GT4. In GT4, all other things remaining equal, as you increase damper values ride gets harsher and firmer.

sucahyo
About damper is velocity dependent thing, I measure it relative with other car. When I follow Hyundai Atoz GLS, there is also other car moving at the same speed. On bump where Hyundai Atoz GLS has problem, those car do not.

As damper velocity (the speed at which the damper shaft is travelling) can only be accurately measured with a damper dyno or state of the art telemetry I seriously doubt your claim.

Even if the two cars were going at exactly the same speed the damper velocity would still be dependent on the actual un-sprung weight of the corner in question and thats very unlikely to be the same.

sucahyo
If you never see Hyundai Atoz GLS maybe you can notice other car that show bouncy behaviour, see how it's tire behave on successive bump. Maybe an old Civic or Lancer.

About Subaru 360 vs Hyundai Atoz, I only want to let you know that fast tire up and down movement in Hyundai Atoz GLS is so much alike to the one that happen on Subaru 360.

Ive seen an Atoz on many occasions, even had the misfortune to drive one, but as the standard suspension set-up for the UK/Europe is unlikely to be the same as for your part of the world its another pointless comparison.

You are also still trying to compare the suspension reactions (visually only once again) of a modern FWD car with one of a old RR car, it cant be done that easily.

sucahyo
And more important than vibration, no explanation about increase of damper stiffness make more suspension noises. On small succesive bump, my bike broken damper makes more noises than the new one. My dad's car original damper makes more noises than the new one.

Do you seriously expect me to pass comment of this?

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 cant prove a damn thing about them one way or the other. Ive asked you to prove that a stiffer damper was indeed fitted to your dads car, rather than simply a replacement of a fault damper and you have not even managed to do that.

sucahyo
When the car still wallow and the noise is reduced when we increase the damper value, it could only mean damper tuning is reversed.

Still wallow, what a great and definitive piece of proof!

Do higher damper values (all other factors being equal) cause wallow to increase or decrease? Thats the question that you should be asking, and the answer is higher damper values reduce or eliminate wallow. Indicating that damper values are not reversed.

Noise is reduced, well for someone who gets the B-spec mode to do most of his testing I fail to see how you can actually comment on this so definitively. The simple fact is that as damper values increase (all other factors once again equal) the noise gets harsher, and in the very general world of GT4 that would indicate that higher values are stiffer.

This is of course on top of the straight line brake test in the GT4 Dampers thread (which you seem to be ignoring), the Integra touring car test from the same thread and the opinion of every other person who has tested any of this, all of which clearly indicate that higher damper values are stiffer.

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. Yet you ignore what does not support you and focus on the ambiguous visual areas of GT4 to try and prove anything that you believe will support your stance.

This desire to ignore what does not fit your view and dismiss it out of hand is quite simply evidence of a biased and flawed approach. A good example of this is the increase of default damper values as you up the suspension grade, to a reasonable person this would indicate that as the spring rate increases so does the damper value, indicating that higher damper values are stiffer. However when I asked the question of you initially it was ignored and when pushed you tried to say that PD just messed it up and did not care. Then you threw in a ridiculous theory about how PD wanted us to set-up and run race cars with stiff springs but soft dampers, and tried to use the BTCC as an example of this!

Can I ask have you ever heard of Ockham's razor? Roughly translated it says All things being equal, the simplest solution tends to be the best one.

Now if we apply this to damper values as we change suspension types in GT4, we know that as we get more race orientated with the suspension that the spring rates, stabilisers, ride height and camber settings all get more race orientated as well. For the true suspension settings this means firmer. So the most simple and straightforward approach is that damper values are also getting firmer. Certainly its a lot more logical and straightforward than any of your explanations

I am also rather concerned that you have not yet posted in the results thread from the Midfield Caterham challenge that we both provided settings for, it would have been polite of you just to put a quite post together thanking the numerous drivers for the time they put in. Yet not a word from you, no response to the feedback they have provided at all. All other things aside a quick note of thanks to them should not be beyond you.

Regards

Scaff

Dave_George · Dec 28, 2006

Hi,

This is my first post on here in a while, I hope I am not treading on anyones toes by butting in and adding my bit (mods..) but felt it might help.

This post is directed at Sucahyo:

I have had a couple of cars now in the real world that I have upgraded the suspension systems on, in both cases i used adjustable dampers (Koni) in conjunction with a suitably uprated spring (Eibach).

The Koni dampers are quite simple to adjust being supplied with an adjuster which you simply fit to the top of the strut and turn clockwise or anti-clockwise. The adjuster is marked with + and -, hence increasing or decreasing the effect.

Driving a stretch of road with the dampers set to full in the - direction and you get a car that absorbs bumps nicely, ignoring the uprated springs here which reduce roll the dampers set to this - setting are absorbing more and can be said to be set as "soft".

Drive the same piece of road with the dampers turned all the way to the + setting and the difference is very noticeable. The car feels much stiffer and reacts to bumps a lot more, even small irregularities in the road surface can be felt. Ultimately the car turns better and handles tighter but its at the expense of ride comfort which ultimately decreases and another side effect is the dashboard of the car rattling etc. Set fully to the + direction the dampers are said to be "Hard" ie they are resisting movement more.

Gt4 is set up the same way. Anyone with 5 minutes and a simple dual shock controller can feel this and experience it in the handling of the car.

I think you need to take a step back from all of your ideas and look at what is being said to you. It takes a lot to admit we are wrong sometimes but I think you need to evaluate all of the facts that have been put to you so far.

I know nothing about how a damper works really but Scaff obviously does and you should not question his and all of the other peoples knowledge that he has used to back up his points.

I havent been around for a couple of months and it amazed me to see that this issue you have is still ongoing and that you persist with this ignorant attitude that chooses to discount information just because it doesnt fit with your ideal.

take a step back, look at the facts and stop wasting peoples time (people who have a lot to give to gtplanet but are eternally battling with yourself over something everyone else seems to be able to see)

Deal with it and move on!!

regards

David

eg6_dude · Dec 28, 2006

Not that I'm trying to offend anyone, but shouldn't you mods and veteran members move this disscusion to the actual damper thread and out of the step-by-step tuning of an Alpine. The Alpine hasn't been in this conversation fro a while now.

Also to me this seems like a very long argument, backed by half fact and half opinion between Scaff and Sucahyo (although Scaff's side seems more factual).

To be honest I have been reading this thread since it began (not daring enough to state my opinion on real life/GT4 damper physics) and neither member is getting through to the other one!

Might be time to call it quits!

(JMO, I know Scaff is a smart guy and I have alot of respect for him. Sucahyo should also take into consideration that maybe his understanding of tuning isn't yet fully developed yet (ex. Weekly tuning challange results) and he should listen more to what Scaff has to say,as I think he is in over his head.)

Please don't be offended.

(**running away quickly**) :nervous:

Scaff · Dec 28, 2006

eg6_dude
Not that I'm trying to offend anyone, but shouldn't you mods and veteran members move this disscusion to the actual damper thread and out of the step-by-step tuning of an Alpine. The Alpine hasn't been in this conversation fro a while now.

Also to me this seems like a very long argument, backed by half fact and half opinion between Scaff and Sucahyo (although Scaff's side seems more factual).

To be honest I have been reading this thread since it began (not daring enough to state my opinion on real life/GT4 damper physics) and neither member is getting through to the other one!

Might be time to call it quits!

(JMO, I know Scaff is a smart guy and I have alot of respect for him. Sucahyo should also take into consideration that maybe his understanding of tuning isn't yet fully developed yet (ex. Weekly tuning challange results) and he should listen more to what Scaff has to say,as I think he is in over his head.)

Please don't be offended.

(**running away quickly**)

A good post and I feel in particular the reason this thread has not been locked deserves an answer.

I have tried to move the conversation over to the damper thread (in particular by setting up further testing, etc) and came close to locking this thread last night. The only reason I did not was because of Famine's question.

However you are quite right that is the correct location for the subject to be discussed, so without any further ado I'm going to ask that this be continued in the damper thread and lock this one up.

I will put links in both for background context, etc.

@ Sucahyo - Please reply to Famine and myself in the GT4 Dampers thread

https://www.gtplanet.net/forum/showthread.php?p=2522680#post2522680

BTW - in regard to my own reasons for not letting this one drop, well its quite simply. I have a huge issue with incorrect information or opinion being posted as if it were fact. Every single piece of information I post is backed by a verifiable and checkable source, non of it is conjecture. Sucahyo however posts a lot of 'pet' theories and at times completely incorrect info as if it were fact and quite simply I can't let that happen. Subjects such as damper can be difficult enough for people to get to grips with, adding in a torrent of miss-information just makes things far more difficult than they should be.

Regards

Scaff

Step by step tuning Alpine A310

sucahyo

Scaff

sucahyo

Scaff

sucahyo

Scaff

Famine

GTP Editor, GTPEDIA Author

sucahyo

Famine

GTP Editor, GTPEDIA Author

Scaff

Dave_George

eg6_dude

Scaff

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