About dampers in bump vs rebound

There's no official guide whasoever.. Kind of expected.

 

well for sure you are not alone in there.
I've been working on sims for 20 years, I know EXACTLY what a damper does from a physics/equations (not a major accomplishment tho.. it's literally 1 multiplication ) point of view but I have absolutely NO CLUE how to translate that into something useful for a car setup , and I have no interest in acting like I know either .
When we don't understand something it's much better to be open about it then trying to come up with messed up theories... that's what religions to, leave it to them.. no shame in saying "I don't know" right?

 

I'm not sure if it is actually possible to give general advice on setting up dampers other than "rebound should be stronger than bump" (to avoid that the car oscillates after bumps).

Here is a guide about using MoTeC for GTR2, which describes a relatively straight-forward way to set up the dampers and also shows how to use a histogram to check if you're going in the right direction (something which we unfortunately can't do in AC):
https://issuu.com/ibyte/docs/gtr2_motec_i2_pro_beginners_guide

He also gives advice on how to proceed when setting up the dampers.
However I'm not so sure if it's a good idea to remove the damping completely as a starting point.
All that'll do is to show you that you need dampers because otherwise the thing will wiggle around like crazy. ^^
Should also note that I didn't test it like this in AC, because I'm usually quite happy with the dampers setup. There were only few cars were I needed to adjust them.

 

Gold star to you!
First, people, none mentioned none forgotten, need to understand what a damper is and not is. A damper transforms motion energy into heat energy via friction (several types of friction), nothing more nothing less.

@Lord Kunos
Since you read this I would like to ask some questions, just out of curiosity. (take it with a grain of salt )

- Do you have plans to add damper fluid heat build up?

- What about linkages? Change angel of the shock to get more or less progressive rate? From my RC-car experience I learned that leaning the shocks inwards also reduces body roll quite a lot.

- Adjustable mechanical anti squat? Made huge differences RC-car.

- Spring binding due to rotation when compressed? I have experimented with using thrust bearings to reduce binding on my mtb shock. Could feel the difference in a controlled test but don't know if it helped on the trail.

Don't know if any of this is "relevant" in a sim, just asking .

A long time ago on a MTB forum there was a discussion if titanium springs improved suspension characteristics compared to steel springs.
In the end I got so fed up with all the guessing that I measured the weight of a tire valve cap, calculated the centripetal force and added the suspension leverage ratios from the most common bikes.
The numbers showed me that removing the valve cap from the rear wheel made about as much difference to the forces on the damping as changing to a TI spring. The theory was that the lighter spring would accelerate faster due to less mass (moment of inertia). The math was not appreciated by the "I have a ti-spring, I am cooler/faster than you squad" .

 

Amen!

 

I am not opposed to the idea provided I can get enough relevant data to make something that makes actual sense and not just a "let's put some random numbers here and there"... this thread obviously proves how clueless we all are already, I don't think that adding more stuff will make things better

 

I understand that frustration. There was only good stuff in this thread and then it all got messed up :-(

Your metrics can't stand ground in a systematic approach. You managed to go through the achievements with that particular setup guide, so it must be good. I'm finishing top 5th in most online races in my undies, so they must be good for racing.

Just last night I fiddled with springs and dampers in the BMW m235i racing. I liked my tweaks and decided to go a bit higher on the negative camber. Next Q stint, I destroyed my PB by 0.4 s and thought "Yeah, I'm a setup master!" just to find that in some save/load mistake I had reverted all the suspension/damper settings, only tyre pressure adjustments (much bigger influence on lap times) and fuel was left.

Still I re-did the suspension/damper adjustments because I enjoy the car more this way and feel more confident. During the race, I pulled times some 0.1 - 0.2 seconds slower than my PB but felt better with the car. Certainly, in a concentrated lap I'll be able to improve my PB on the stiff setup.

As for the common Spa GT races - in these fast turns you can lose so (!) much time...turn after turn and it adds up. There's a group of people that race there, a lot and they have just gotten very, very good at it. That's all.

@Berniyh: I don't entirely agree when you say the dampers are something you don't consider until you have to. Maybe it won't gain you much for your PB but it will give you consistency during races and in the long run you can achieve better times through confidence. @Stereo put this very well - the damper does its job as the car moves about and everyone likes their car to move about, differently.
Also, the Huracan cup car is completely turned around by small damper tweaks. In default setup the tail just flies away at some point at high speed cornering. Some tweaks (even at the front, quite interesting) and it's stable.

All in all, good discussion in here

 

I would like to agree with you on this.


I ride my bikes (bmx, mtb and motorbike) very much with the sole of my feets, feel the terrain and from instinct know when and where to push, pump or jump. All this feeling comes from the suspension (linkage + spring + damper (tires, frame flex as well but...)). Other stuff like head angle (caster on cars, rake on motorcycles) are way more concrete, at least for me. Slacker head angle gives you more control in high speeds and steep terrain...
So whats most important, the subconscious feeling that you know where the bike are under you and how it moves together with your body language or the concrete "fact" that slacker head angle gives you more stability in high speeds and steep terrain.

It is hard to translate this into a racing game but I hope you get the point.

Less aero = faster in a straight line, more aero = slower...
Changing damper settings = alter the total feel (motion of the car) of the car.
Make the third gear shorter and it "only" affects the third gear, reducing LCD changes the car in all stages including when the driver enters the car. This is why your daughter don't care if you change toe on your old Chevy with leaf springs, but she will kill you for putting in those dampers...

That's why I think damper settings are a bit scary, you have to know what you are looking for in every single situation, something I have a hard time doing in AC where you for obvious reasons can't feel the movement.
However if/when I get the feeling of knowing how the car will move, damper settings helps me a lot.

A mtb paradox:
A rider wants to get more stability in high speeds. He slackens the head angle and says "I have to test this on the hill to see if it helped" and goes for a ride.
Same rider wants to get more pop in the bike.
He again stops by the car at the bottom of the hill and adds a little bit of LCD (the bike keeps its posture going up a jump) and reduces LRD (to let the spring extend faster and help him "bounce" of the lip). After he has turned the knobs he jumps on his bike and rides around on the parking lot. After a couple of laps he says "feels much better".

The paradox.
In the first example he thinks he has to test the bike because he can't feel the difference without getting into a certain situation even though all the facts tells him the bike will be more stable.
In the second example he changes the total motion of the bike, how it reacts in every single situation. When he rides around the parking lot he can immediately feel the difference, and as we all know a difference is always better (sim value in ini-file ).
For some reason the rider accepts this parking lot feeling as a proof that the bike will pop more in a TOTALLY different situation.


All this goes back to where I wrote something about experience.
You don't need experience to change gearing but you do to change damping (in general terms).

 

I agree with @LeDude83 about dampers having a particularly role on how confident and feeling in control of a car one is.
It doesn’t necessarily make it faster by using a different damper setup, but the confidence in driving can, by itself, allow better times, despite the physics aspect of the setup for driving dynamics.

My car has different suspension settings which really only affect dampers (stiffer or softer) and when driving in track I feel more confident and in control when using the “sportier” settings.
Curiously I had other person driving my car and with the softer setting he did better lap times than me and even preferred the car that way (easier to control, he said), therefore for sure it isn’t the stiffness of the dampers (setup alone) by itself that help to improve time.

The engineer and physic side of thing can be very interesting but driving it’s all feeling dependent, so the setup that allows more confidence in driving, is it in RL or in simracing, is in fact the best setup and that is the main reason why in simracing someone's setup can be a nightmare to another and so may times when sharing setups there are complains saying “how can you drive with the car like this”.

 

There are some cars that I find more easy to feel the changes in damper settings, one is the Shelby cobra, because you literally see the front of car ducking in different speeds. Probably on cars with higher hz settings on the spring the visual effect is not that much. Other than that I try to follow some "rules" as in some guides, but it might only work for more tradicional cars with not much aero. There's the critical damping %, I'm usually scared to go bejond 1 on the car engineer app (that'd be 100), but certainly I have no clue why.

Definitely you see cars setup with "more" bump setting that rebounder (or higher if it applies best) but it's due it suspension geometry and stuff, so each car has its own setup parameters.

Please feel free to correct me if I'm saying absurd things

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You can do that on AC using aim software race analysis

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I'm similar to @Leonardo Ratafia, I tend to avoid more than critical damping.

Anyone know why you might want it? I'm sure I've seen it on some cars.

 

+1 on that Shelby comment. This particular car IMO needs damper tweaks both from a pure physical and a "feelgood" point of view.

Thanks for the hint to setup engineer app - the critical damping thingy is what I clumsily described in my first post in this thread. It's what covers the danger of oscillations, the suspension instrinsic frequency etc. Sounds like the setup engineer might help to get that mathematical stuff sorted for you.

 

Hm, I used RaceStudio instead, but the available channels should be the same? I didn't find a channel that for the suspension movement speed (or any similar name).

 

+1 on Cobra.

I have never heard the phrase critical damping before so I hade to google it.
What I don't understan is if critical damping in some way "merges" rebound and compression and described the total amount of damping? Maybe @Lord Kunos knows this?


From now on I'm on thin ice and might be speculating a bit .

There are situations where overdamped (rebound) are useful, however I don't think they are relevant to AC.
If you are planing to jump your car (mtb, mc) you want a compression damping that keeps the car at the right pitch at the lip of the jump.
When it is time for landing you want a fast rebound and copression (not stupid fast) at the top part of the stroke (position sensitive damping) so that the wheel can track the ground during the initial part of the "landing phase".
If not the the car can be unsettled by a bump hitting one wheel before the others have touched the ground.

In the second part of the landing phase (4 wheels on the ground, deep in the travel) you want quite a lot of compression and rebound damping so that as much energy from the landing as possible turns into heat and by that distributes the G forces from the landing over a longer period and so the car does not bounce back up again. If you are a "one hit wounder" there is no reason for the car to even rebound back up again.

This might be totally wrong but it sound good in my head.
There is a free fall attraction at the local amusement park with quite large shocks that catch "the ride". I think they are air springs (don't know about damping). "The ride" lands on these shocks and bounces up again, but it locks like every time "the ride" hits the shocks the shocks release some air and by that taking away energy from the bounce. On the last bounce the shock are so weak that they can't even start to rebound the ride and starts to smoothly release the rest of the air to let the rid get back to the ground. To be honest this I just me guessing but standing in the que looking at it for 20 min it really look something like that.

 

I'm sorry for my ignorance, but all the (little) tweaks I've done on dampers so far were based on feel. Could someone explain the frequency thing and how to use it to set the car up?
Edit: I may be way off here, but from my understanding the dampers control the frequency with which the springs can move, and so I want that frequency to match the frequency of the oscilations on track. But does that just apply for fast bumping or regular bump as well? Should I be using telemetry for damper setup?

 

This might help you.

 

You need to use some of the racecar profiles on aim software and then press F6 and opens that histogram iirc. (it happened to me that the F6 option was greyed out and it was that I was using like a Karting profile on aim or sth)
Further more there's an ini file in AC that enables to debug physics and I think you get even more channels but I never tried it so I'm not 100% sure.



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This setup guide always helped me when I raced on netkar pro.
https://www.scribd.com/mobile/document/49703556/MaiDireSetup-Ver-1-1-2-English

Probably a Gt3 car is a bit harder to setup though

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Pretty sure I had that activated when acquiring the data I was looking at yesterday.

But I'll have a look.