b505

This is great! Thanks for providing that data and all your research. I'm actually curious as to knowing a little more about the conversations you had with the engineer in charge of helping you dial in your S. I've heard mixed theories on biasing suspension setups toward rebound vs compression. They say most race cars are valved toward a heavily compression biased setup while street cars can be fairly neutral. I didnt know how much a modified street car would be considered a "race" setup. But overall it looks like the recommended numbers had your goal aimed at being rebound biased up front and fairly neutral in the rear.

I've found a very similar setup on my coilovers does the trick quite well (through trial and error and a notebook). What tracks did you guys design this to be ideal for? And did you happen to ask what happens when you change to r compounds or aero in the future how it might affect your suspension tuning goals?

Thanks again for sharing!

anorexicpoodle

So obviously the car is setup to cope with the atrocious pavement we have here at southern California tracks BUT I would not suspect the tuning methodology would really change much for another region since a bump is a bump and if the track is smooth but my car can handle bumps that just means I can use more curbing . From here on is really only my rudimentary understanding so take it with a grain of salt: Really what this setup provides is platform stability. The spring rates on the car are 900f/780lb rear and it now rides smoother than it ever did stock. The reason being is the heavy spring rates provide most of the compression resistance needed already and then you just need to control the rebound of those heavy springs. In the front you want more rebound to keep the nose from unloading too fast after braking so the car will take and hold a set. If you run too little front rebound on heavy springs like that the nose will unload too soon after turn-in. As for the rear The S2000 has so little rear travel that running too much rear rebound (like the evasives did) will cause the rear to down-jack to the bumpstops and stay there. This was born out on the evasives I ran. The idea for low rebound in the rear I THINK is to recover your travel as quickly as you can to keep the car "suspended" and preserve travel.

Honestly I doubt the dampening will change much when adding aero. The biggest change might be to my rear spring rate to help re-balance the car so a wing doesn't push it statically into the bumpstops but otherwise the idea is that if you introduce aero into a shock setup like this where the suspension is already interpreting the road without upsetting the car to a degree, now as long as you add balanced aero all it does is increase the effective traction limit. I already experience this on my lemons car when adding aero. In high speed corners with poor pavement like riverside at buttonwillow, on the evasive shocks my S2000 would buck and heave over the choppy pavement. My lemons car with more compliant shocks and aero, you could feel the suspension working furiously to keep the tires down but the chassis never moved while the car sailed over bumpy pavement. This means I never had to apply corrective inputs and could keep things smooth which meant more time on the gas and more effective use of the available traction and thus better times.

I think if you follow the shock tuning going on in the miata community (Supermiata, Miata challenge, etc) you'll find that they are several years ahead of what we are doing here just due to the pressures of more competition driven development going on, and the really fast setups (949 racing Xida suspension, FatCat motorsports etc) are all trending toward these sorts of low compression curves because they make the car easy to drive, and easy to drive fast because the car becomes more stable and thus encourages the driver to push the envelope. Obviously the exact numbers of the setup are tied to spring rates and chassis weights etc but the general idea is portable.

I look at it like this, anything that makes the car easier to drive, makes the car faster and more consistent. Period. I don't think anyone will argue with that statement.

andrewhake

I don't trust you I want to see videos before and after.

thomsbrain

There seem to be a couple schools of thought right now in S2000 community. On one hand, there are people reducing spring rates and using shocks that can create very steep and sharply digressive compression curves. They use lots of low speed compression to control the body rather than spring, then the curve knees over on the higher speed stuff in an attempt to retain compliance. You need a pretty magic shock to accomplish this, though.

Then there's the camp that run really high spring rates and very little compression.

I'm not smart enough to know how that affects all car behavior, but I would imagine the high-spring-rate approach keeps the body more controlled in sustained loading, while the low-rate approach favors transitional body control.

I'm weighing whether to have my Bilsteins vavled by Ankeny/Fat Cat/PSI for high spring rates or whether to go with Ohlins DFV for low spring rates. I live on a really bumpy mountain pass and need a Buttonwillow-style setup that can be composed and compliant over sharp bumps. The DFVs sound comfy but I worry that on long sweepers on track they are going to settle into the bump stops due to lack of spring.

TWF

That is pretty much standard digressive valving which you can get out of most shocks if you valve it that way.
I don't have much experience with cars but seems people are lowering cars to much and running out of the travel, than compensate with stiffer springs. I run in this problem with my car and kept raising it up until I could use travel. Every time I did it car got better. I raised it 3 times and if I have kept it I would have raised it again and lower spring rate.

TWF

Ryan, your lemons have progressive spring as well. And is totally different car, not sure you can directly compare it to s2k.

SHG_Mike

If we are talking strictly road racing with unlimited rules you would want to set the spring rates just stiff enough to hold alignment angles (according to what your tire temps and wear dictate) and maintain the proper F/R balance mid corner.

Dampers do not limit body roll they merely control how long it takes to get there. On a quick bus stop type corner a stiff low speed damper will act like a stiff spring however on a long sweeper 'carousel' type turn you will roll just a much as the spring will allow, but I think you understand that.

IMO the key is to use both a digressive damper AND a sufficiently stiff spring. A Good damper even with sufficiently stiff springs 14/16/18K springs will still feel compliant on the road while maintaining steady state body position. The reason I believe dampers like the SRC feel so stiff and harsh is not the spring rate but the fact that the damping curve is linear and very steep. At movements 7in/sec + you will be rapidly approaching an effective infinite amount of force where the piston just isnt allowed to move fast enough. making the suspension solid and unable to move.

While some dampers like the DFV have some extra special super high speed blow off ports, its not impossible to have a nice digressive curve in a sub 2k set of dampers.

oinojo

Just for reference. Guy's car is running on what I believe is 900/600 last time I spoke with him. I wouldn't consider that a stiff setup running little compression. The shock forces need to be within a range that will work well (black art figuring that out). To me it seems that the EVS is too aggressively valved on the compression side and not enough on the rebound side for the front. The opposite is true for the rear. That is nowhere near as stiff as EVS 900/900 setup. Speaking of valving, I just got my Penske shocks back (refresh)from him today and couldn't be happier. Silky Smooth.

anorexicpoodle

Not a direct comparison but more of a wake-up call that if it can handle this good on pieced together junk yard suspension, then there is no excuse for my S2000 on good shocks to not handle at least that well.

albertg

Ryan, did he provide you with more shock plots? ie. force vs displacement, cvp, etc?