davepk

Statueman,

Thats very interesting... Thats exactly the conclusion I've come to as well...

Jason Saini

Keep in mind also that tire pressure also has a spring-rate associated with it. The more pressure, the less compliance in the tire. Back during the only autocross we ever ran with S02's, we tried as high as 38-40 in the front. If I had a chance to do it all over again, I would probably try even higher pressures in the S02's... which would lead to them getting greasy quicker on the track. I noticed that the stock S2000's I drove at Laguna, (calc's car and a totally stock yellow one.) seemed to wallow.

Also, DavePK's car on the A032's seemed to wallow quite a bit as well. Obviously, the suspension has much to do with this, but tire pressures are a factor as well. We were running 45 all the way around (hot) in the Kumhos for the December track day, and the Hoosiers for January's day were set at 42 cold. At one point they reached 50psi, with no real detriment to the handling. We also ended up running them at 45psi hot, which gave great stability.

Not saying it would work on A032's, but it would be interesting if someone tried it. On our autocross car we run about 38-44 in the Hoosiers at autocross temps... much lower than track temps.

I look forward to doing some more testing! Research is fun.

Prolene

[QUOTE]Originally posted by Jason Saini
[B]Keep in mind also that tire pressure also has a spring-rate associated with it.

I noticed that the stock S2000's I drove at Laguna, (calc's car and a totally stock yellow one.) seemed to wallow.

We were running 45 all the way around (hot) in the Kumhos for the December track day, and the Hoosiers for January's day were set at 42 cold.

jguerdat

Is this "wallowing" the same thing as the "corkscrewing" that others have reported at track speeds? The description seems to be that the rear end ends up rotating at high speed...

Prolene

[QUOTE]Originally posted by jguerdat
[B]Is this "wallowing" the same thing as the "corkscrewing" that others have reported at track speeds?

Jason Saini

The wallowing I experienced was very hard to distinguish from tread squirm or soft-sidewall tires... But the distinguishing factor was the 'tip-over' that stock S2000's are prone to. The front rolls way too much, causing the rear to tip over also (seeing as how the chassis is so stiff, and the rear swaybar is so stiff.) That lifts the inside rear wheel, and if you are not smooth with your inputs can very easily become the porpoising or corkscrewing effect that so many of us have felt. With the stock cars at Laguna, I found myself having to brake really early, get back on the gas slightly before turn-in, where as with the King car I could (and had to) trail-brake a bit to get the car to rotate. I was running (unofficially) around 1:52-53 in calc's car, and it was quite an adaptation switching between the Mugen car and stock ones...

Initially, I loved the handling of the stock S2000 when we got ours last fall... then we modified it for autocross with a bigger front bar and shocks... then I drove the King car. Obviously, each one was a big step forward from stock - but each one is also progressively more expensive. I can say this much, though... the stability and balance that is dialed into the King car right now is amazing. We just need a little more grip on turn-in, but other than that the car is so much fun to drive. I consider myself very lucky to have the opportunity to drive it.

Regardless of what suspension setup you get, I highly recommend stiffening this car up. The stock spring rates are somewhat aggressive for the street, but woefully inadequate for the track. The car simply leans too much. Those that rode in the King car at Laguna, remember how little that car 'tipped' over compared to the stock suspension? The lower profile tires, and the fact that they were super-stiff-sidewall Hoosiers helped as well.

But back to tire pressures, I know the pogo or corkscrew effect is not entirely the tires, but I also know that the more we have stiffened the suspension on the car, the better the handling has become (not always the case) so in theory, higher tire pressures might work really well on this car. Like I said, more testing is in order! We've tried the higher pressures, and they seemed to work - so now we have to try lower ones. Is it spring yet?

s2k2fast4me

Is this really your experience, Jason? I would think that lower pressures would lead to more compliance in the tire, which would lead to more "twist" under cornering loads, which would lead to more heat. I guess if you go too high on pressures you will eventually overheat the center of the tire since you will be reducing the contact patch. I would expect too low pressures would mean more heat in general, esp. on the shoulders. The SUV blowout due to low pressures comes to mind.

-Andy

busaboy

I agree with Jason. I'm running Advance Design Shocks with 380 lbs/in rear and 340 lbs/in front. The difference in handing is amazing. No roll, very, very crisp. The ride is fine for the street, even on very bumpy roads. I like the car much more with these stiffer springs.

davepk

Busaboy,

I take it you are running with stock shocks?? And only replaced the springs?? Do you have a part number for the springs?

Jason Saini

If I remember correctly, the Advance Design are Ground-Control's shock setup. They are double-adjustable, I think. Check out GC's website. I didn't know they were available for the S2000, though. Sounds like an interesting setup. It's the first I've heard of someone running softer rear rates... I wondered if that would work well. busaboy, how is the car's balance with that setup? Both the stock springs and Mugen coilovers that I've driven on have softer front rates.