Suspension Dampening Cheatgrid

  • Thread starter budious
  • 68 comments
  • 9,669 views
Making sense of it all... first lets strip off the polarity from that grid since I'm fairly certain it doesn't exist anyways.

First concept, strip away the idea that rebound and bound are independent variables for opposing rates and reorganize your thinking that each is essentially behaving as its own spring, bundled upon one another, and that their combined value equals your overall damper value. This gives a value range from 2-20, I call it the Combined Dampening Value or CDV.

---Rebound--------------Bound---|---CDV---|
---------------------------------------|-----------|
------1------------------------1------|----2-----|
------2------------------------2------|----4-----|
------3------------------------3------|----6-----|
------4------------------------4------|----8-----|
------5------------------------5------|---10-----|
------6------------------------6------|---12-----|
------7------------------------7------|---14-----|
------8------------------------8------|---16-----|
------9------------------------9------|---18-----|
------10----------------------10-----|---20-----|
---------------------------------------|------------|

Second concept, consider how your car is setup and tuned. Some cars may require a different balance of dampers to match their ride height and spring rate. Typically each one will have a combined damper value threshold that once passed results in diminishing returns for stability and control.

You can find this threshold by increasing rebound and bound proportionally until the car becomes unstable and you have difficulty controlling it. Typically a threshold can be determined by R-1=B or R+1=B or R=B; R=B being a special case in which the car is on the threshold and retains some stability but any other combination of R and B to arrive at the same CDV results in instability. In the case of R=B; than R+B=CDV+1.

Ex. If the only CDV of 16 you can find that is stable is Rebound 8 with Bound 8 than your threshold is likely 15.

So this is where that whole concept of inverse rebound used to came into play for all the wrong reasons; again back to our chart, this time slightly changed up, and directly applicable for the example above of a damper threshold of 15 (or 16).

---Rebound--------------Bound---|---CDV---|
---------------------------------------|-----------|
------1------------------------1------|----2-----|
------2------------------------2------|----4-----|
------3------------------------3------|----6-----|
------4------------------------4------|----8-----|
------5------------------------5------|---10-----|
------6------------------------6------|---12-----|
------7------------------------7------|---14-----|
--------------------------------------------------- This examples' damper threshold reference line is placed here since CDV 16 comes beyond it.
------8------------------------8------|---16-----|
------9------------------------9------|---18-----|
------10----------------------10-----|---20-----|
---------------------------------------|------------|

Here, I am using R+(-) simply as a means to flip the corresponding rebound value and to shift it's position in relation to the damper threshold line for purposes of illustrating the concept in reference to the example.

CDV[R+(-)] simply represents the resulting CDV from pairing the R+(-) value adjacent to the Bound value on the grid, so it gives you a column of resulting combinations of Rebound and Bound that are equal to 15.

---Rebound-----R+(-)----Bound---|---CDV---|--CDV[R+(-)]--|
---------------------------------------|-----------|---------------|
------1------------------------1------|----2-----|----------------|
------2------------------------2------|----4-----|----------------|
------3------------------------3------|----6-----|----------------|
------4------------------------4------|----8-----|----------------|
------5-----------10-----------5------|---10-----|------15------|
------6------------9-----------6------|---12-----|-------15------|
------7------------8-----------7------|---14-----|-------15------|
--------------------------------------------------------------------
------8------------7-----------8------|---16-----|-------15------|
------9------------6-----------9------|---18-----|-------15------|
------10-----------5----------10-----|---20-----|-------15------|
---------------------------------------|------------|--------------|

You can make a chart for each car you tune depending on whatever you determine the CDV for the car to be, but you really don't need to, just test all combinations of Rebound and Bound that up to the desired CDV you are seeking.

Still lost on this? :dunce:
 
Z1-AV69
@budious: The effects of a stiffer rebound than compression are quite present in the game. Making rebound 1 tick stiffer than compression will give you understeer on the brake and oversteer on throttle, as I would expect. So I think those two settings do what they say.
Click to expand...

That is only because it stiffens the upper half of the dampening travel more than the bottom and the body (weight transfer) of the car is slowed, the effect you observed is correct, attributing it to a properly implemented rebound feature is where you get it wrong.

In fact I know that is complete BS because I ran my STi tune for the competition on the new Cape Ring time trial event with Rebound @ 7 and Bound @ 1, and put in a 2:56.220" time. My entry car, I will be publishing full specifications soon, has a damper threshold of 8 and will be the perfect test case car to work with. I found all of the following to the usable combinations with it:

  • Rebound 1 / Bound 7
  • Rebound 3 / Bound 5
  • Rebound 6 / Bound 2
  • Rebound 7 / Bound 1
  • Rebound 4 / Bound 4

All these combinations adding up to 8 proved rather stable and provided consistent lap times on the car. A few combinations proved not to, namely the ones not included.
 
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I think I can understand your theory, but what test do you use to prove it?

BTW: If rebound does what it says, the suspension will come back "out" slower. Under the assumption of some progression of the springs while compressed, increasing rebound will keep the suspension in a territory of an overall stiffer suspension more. Wouldn't this explain your findings?
 
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Z1-AV69
I think I can understand your theory, but what test do you use to prove it?
Click to expand...

I used this theory to setup my Subaru Impreza Sedan STi '10 tune for the competition on the new Cape Ring time trial event with Rebound @ 7 and Bound @ 1, and put in a 2:56.220" time. My entry car, I will be publishing full specifications soon, has a damper threshold of 8 and will be the perfect test case car to work with. I found all of the following to the usable combinations with it:

  • Rebound 1 / Bound 7
  • Rebound 3 / Bound 5
  • Rebound 6 / Bound 2
  • Rebound 7 / Bound 1
  • Rebound 4 / Bound 4

All these combinations adding up to 8 proved rather stable and provided consistent lap times on the car. A few combinations proved not to, namely the ones not included.
 
I edited in another question into my last post.

The existence of a sum of bound+rebound as an upper limit to what works doesn't necessarily mean your theory is right. The stiffer your bound is, the less travel is available the more important it gets to have the suspension rebound fast to keep some suspension travel.
 
Then why would a rebound 5 / bound 5 setting be stiffer than a rebound 3 / bound 5 combination? If rebound is faster at 10 then it should be softer, if Rebound is faster at 1 than the latter is softer. A rebound 1 / bound 1 or rebound 2 / bound 2 setting results in a very active and plush suspension... So why then can I use a Rebound 7 / Bound 1 combination and do 120 MPH through the spiral loop at Cape Ring and not have my suspension bottom out. Because in all these cases the effective dampening rate is 8 and it works in both directions.
 
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If cars bottom out at all is another question. Cape Ring is a very smooth and even track, suspension is not all that important there. In that spiral loop it's all about tires if you ask me.

But your example of 5/5 vs. 3/5 might be the test I was looking for. Will have to try this after work.

Edit: After thinking again this example fits into my theory of non-linear spring rates over the travel too. A faster/softer rebound will bring the suspension back into the (softer) spring territory faster, resulting in an overall softer suspension.
 
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The lack of good, hard and solid data from tests is really frustrating. I think we all should discuss such issues much more to escape from the individual subjectivity. So thanks for your work and sharing, even if I disagree with your conclusions. ;)
 
budious
Then we're all in agreement to be equally confused... then it's settled.
Click to expand...

Budious just a quick thanks awesome effort.
Doing some of your tricks at Daytona and some improvement in times ,but tire wear is another issue.Just a question,what about toe and camber as it plays a huge part at Daytona and Indy.
Thanks
 
killerjimbag
Budious just a quick thanks awesome effort.
Doing some of your tricks at Daytona and some improvement in times ,but tire wear is another issue.Just a question,what about toe and camber as it plays a huge part at Daytona and Indy.
Thanks
Click to expand...

I don't know really, I don't run Daytona and Indy much, it's too much like Nascar for me :)

I make my tunes so plush on soft springs at neutral ride height the tire contact patch has more room to travel with the path of the suspension so I actually have found while I can determine the appropriate camber to pair with my suspension setups, the additional time required for tire warming and for all tires to reach equilibrium of tire temperature to make camber settings predictable, usually just results in the car being slower for the first couple of laps than it would be for no camber; and then, even after warming, lap times only come on par with the none camber benchmarks. I think camber benefits lower ride height tunes far more than it does neutral or positive ride height tunes.
 
stratotone
So does this mean you'll be changing all your Deep Forest Tunery tunes?:)
Click to expand...

Well... it means I'll be looking to apply this theory to them and see if I find any optimizations to be made. Simply because I have DE=DB set to most of them doesn't mean they aren't optimized if the CVD is at it's peak performance threshold, I just need to simply test the other variants to see if one performs better than another, or test that I have the right combined CVD threshold optimized for those cars.

I have like a bunch of work in progress cars and I'm a bit obsessive compulsive through the whole process which is why I don't release them any quicker than I do, most of the ones I did post already were just getting concept pieces out there to show neutral ride height tunes can compete, not everything is best slammed; or full upgraded, read drivetrain optimization in my tuning thread.
 
sukerkin
ENTRY type 1 : Increasing braking + increasing steering
This phase is the first part of a fast decreasing radius turn. This phase will not occur at all if you get all your braking done *before* you turn-in. Since weight is being transferred both forward and outboard, the outside front damper moves in bump and the inside rear damper moves in rebound. these are the dominant two dampers in this phase of turn-in. The other two have minimal effects during this phase.
ENTRY type 2 : Decreasing braking + increasing steering
This is the turn-in phase of a slow corner. This phase may or may not occur depending on the type of turn or driving technique. Weight is being transferred outboard and to the rear, so the outboard rear damper moves in bump and the inside front damper moves in rebound. The other two dampers are considered stationary.
ENTRY type 3 : Increasing steering at constant throttle
This phase can be a chicane turn-in (GP2 has a lot of these!) or a turn entry taken at *full* throttle. Weight is being transferred outboard only, so *both* outside dampers are moving in bump and *both* inside dampers are moving in rebound.
MID-CORNER TRANSITION : Decreasing steering back to zero at constant throttle
This is really the opposite of a type 3 entry. It's what happens in the middle of a chicane, as you flick the steering back away from the current cornering direction. As soon as the lateral acceleration passes back through zero, the turn reverts to a type 3 entry again.
EXIT : Decreasing steering + increasing throttle (or decreasing braking)
This is the apex_to_exit phase. Weight is being transferred inboard and to the rear. The outside front damper moves in rebound and the inside rear moves in bump. The others are considered stationary.
Here's a chart to help understand low speed damper adjustments:
Code: 
 CORNERING PHASE        MORE UNDERSTEER         MORE OVERSTEER

  Entry Type1            F bump +                 F bump -
                         R rebound -              R rebound +
 
  Entry Type2            F rebound +              F rebound -
                         R bump -                 R bump +
 
  Entry Type3            F bump +                 F bump -
                         F rebound +              F rebound -
                            or                       or
                         R bump -                 R bump +
                         R rebound -              R rebound +
 
  Mid-corner             F bump -                 F bump +
  Transition             F rebound -              F bump +
                            or                       or
                         R bump +                 R bump -
                         R rebound +              R rebound -
 
  Exit                   F rebound -              F rebound +
                         R bump +                 R bump -
 
                          + = increase adj.
                          - = decrease adj.
                          F = front
                          R = rear
For reference, here is what I suspect to have been the 'source' article:

http://www.smithees-racetech.com.au/theory/shocktune1.html
Click to expand...


I have read a lot of damper theory and that is sound advice, it's not entirely the same thing I was trying to get at, but the methodology was the somewhat similar. Total damper count is relational to spring rate and anti-roll bar setting, using the inverse theory, then front to rear is set up something like this to play off each other. Using the traditional theory you can set each suspension independently. Kind of like what he's described as Entry 1 / 2; as opposed to Entry 3.
 
I read this all and its so useless and time consuming and confusing to try and calculate all of this over some dampers.

The higher the # though the harder the dampers are (aka the tires can move up and down very fast) and Im pretty sure you are trying to say the opposite which I have found untrue throughout all of my testing
 
Poppins
I read this all and its so useless and time consuming and confusing to try and calculate all of this over some dampers.

The higher the # though the harder the dampers are (aka the tires can move up and down very fast) and Im pretty sure you are trying to say the opposite which I have found untrue throughout all of my testing
Click to expand...

I'm saying that when you use lower spring rates you need less dampers to counteract the oscillation than with higher spring rates. When you use low rebound and low bound on weaker spring rates you still have a very active suspension, it's relative to spring rate; using a stronger spring rate just requires the use of more dampers overall to prevent the rebound from being too strong. Hence, under any condition you still have an ideal threshold for a maximum damper count, no matter how you want to count it or claim it works. Anyways, use what works for you... I'm not out to change any minds, just to find ones that can collaborate any of it.
 
budious
I'm saying that when you use lower spring rates you need less dampers to counteract the oscillation than with higher spring rates.
Click to expand...

I thought this was common knowledge lol?

If you read the in game descriptions about any of the tuning it is very easy to comprehend and Im pretty sure it says that the dampers are relative to spring rates. I see what you mean now though, before I thought you were saying High Dampers = Looser which was what I was confused about.
 
I'm not sure budious, that was I was testing this morning and it don't work @100% for my Alpine.
I have :
9.0/4.2

So it would mean I would have one in front and half in rear. I have :
3/3
5/4

It's a RR, all the weigth is in the rear, maybe that's because of that : SR/damper counter the weigth in this setup. I'm posting it.
 
I haven't worked on that car but wouldn't a RR be rear heavy and need more spring at the back and less at the front, I'd think your rates be better turned around the other way? The stronger spring would get more dampers and the weaker spring on front the lesser combined dampers, or as poppins suggests, keeping them balanced if the springs are set correctly to support the actual weight distribution of the car, then even dampers front and rear tend to work really well.

Poppins
I thought this was common knowledge lol?
If you read the in game descriptions about any of the tuning it is very easy to comprehend and Im pretty sure it says that the dampers are relative to spring rates. I see what you mean now though, before I thought you were saying High Dampers = Looser which was what I was confused about.
Click to expand...

As far as dampers go... I throw around too many theories, I started the thread with the only intent of suggesting that there are two sides to the larger damper debate; one says rebound is inversed, the others say it's not. I tried to applied test cases to both theories and got positive results using both, so I tried to offer my conditional rules to explain why it is both may work to some degree, then I moved beyond that to say perhaps why both worked was because the system I was attempting to measure did not exist, and my results were simply from other unseen factors. So from there I tried to come up with a theoretical explanation for why all these case scenarios could hold true simultaneously and why something may be unintentionally flawed or deliberately simplified for the suspension modeling. I'm still not behind a definitive theory, my thread was more just of a thinking out loud approach...

Maybe it helps to look at it like this:

40% wt car /////////////////// 60% wt car
---------------------------------------------------RH offset (flat) 0/0
40% wt support//////////// 60% wt support

Opposing forces, different spring rates but support equivalent ratios in weight distribution so the movement speed of the springs are the same although they are different rates. Therefore, putting the same amount of dampers in this case front and rear works because dampers only throttle the speed of the movement, and if springs in ration to weight distribution than spring movement rate is equal front to rear... change the balance slightly then you need to rebalance the dampers to compensate. In this case, being able to achieve best performance on equivalent dampers front and rear is possible.
 
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budious
I haven't worked on that car but wouldn't a RR be rear heavy and need more spring at the back and less at the front,
Click to expand...

I 100% agree with this. With out a low Spring Rate/Damper setting in the Front, you'll get Understeer. This is because all of your weight is centered in the Rear, and with out these low settings in the Front, your not going to get any weight on the Front wheel, thus less traction. These settings will help you on corner entry under braking.

Then I would recommend a High Spring Rate/Damper in the rear. This is to keep the weight on the Front tires during corner exit while accelerating. Without a stiff Rear suspension, you'll send all the weight to the Rear, which will cause Understeer because your Front tires will have effectively lost grip.
 
Tell you what, when i become finish my degree's and stuff and get rich, we need to start a real life team and you can help tune our suspensions! Hows that sound!!! :D

Call me old school, but i still go by feel, and im not trying to undercut your work or anything, which is amazing compared to whatever i could put down on paper. haha

Here is a car that i have created for drift and ive tested it, and i think its a monster, especially for someone with a wheel. Could you possibly tell me how efficient it is? Or at least check out my thread, i would love some of you input :) https://www.gtplanet.net/forum/showthread.php?t=180142

Silvia s13 premium 255hp, stock weight, has body kit.
I use Comfort Hard tires
Wing is lvled to 10 downforce
ECU and Engine lvl 1
Intake manifold and Racing Filter
Sports Exhaust manifold and Racing Exhaust, and Sports Cat back sys.
Standard transmission
Twin clutch and Racing Fly and Carbon Shaft

Suspension

R. Height -5/-5
S. Rate 7.0/6.5
Damper (E) 6/6
Damper (C) 4/5

Roll Bars 4/2

Camber 4.0/1.5
Toe -.15/-.10

The way i have it intended, and from me driving it, it works. The front wheels grip well during a drift while the rear stays maintained.
 
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Poppins
it would probably feel nicer with less front toe more rear toe and the Ext/Comp switched with each other
Click to expand...

Ill have to try that, before this, someone said i should switch my ARB setting, but i liked it at 4/2, maybe because i was used to already. But thank you, i like to tune my stuff and share my findings. :)
 
budious
Maybe it helps to look at it like this:

40% wt car /////////////////// 60% wt car
---------------------------------------------------RH offset (flat) 0/0
40% wt support//////////// 60% wt support

Opposing forces, different spring rates but support equivalent ratios in weight distribution so the movement speed of the springs are the same although they are different rates. Therefore, putting the same amount of dampers in this case front and rear works because dampers only throttle the speed of the movement, and if springs in ration to weight distribution than spring movement rate is equal front to rear... change the balance slightly then you need to rebalance the dampers to compensate. In this case, being able to achieve best performance on equivalent dampers front and rear is possible.
Click to expand...

This is more or less the same conclusion I reached. If the spring rates are appropriate for the weight distribution then the damper compression should be the same front and rear, or at least very close. Damper extension is different however, because it mostly controls the movement of unsprung weight (i.e. the wheel/tire/brake/suspension assembly) as it extends downward. Since this is independent of weight distribution, the extension in this case should be roughly proportional to the spring rates.
 
Back to the damper extension polarity thing; try the following on either the cape ring loop crest or make a course with a jump on Mt Aso in generator...

Set some combination of low rebound with low bound, jump the crest a few times. Set another combination of high rebound with low bound, jump the crest a few times more. At least for the car I'm testing this on, I would say the low rebound is fastest, but you would be deceived by it because it unpacks the springs more quickly; whereas, with the rebound set higher the suspension compacts and then suddenly bursts free upon the momentum of the sprung weight being removed; or the force beneath the unsprung weight being removed; from the opposing force, giving you some sick air time.
 

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