I've been autocrossing for almost exactly a year now, locally in the Seattle area, using my 2004 S2000 (no previous experience at this very demanding game).

My car is stock except for a Gendron bar (the middle stiffness one, the thicker of the two hollow bars). I have it on the stiffest setting.

I recently bought a used (but still quite serviceable) set of Kumho V710s--245/45-17 on the front; 275/40-17 on the rear. It took my son and me a number of runs to figure out the best tire pressure for them (we've arrived at 28 rear, 29 front on the asphalt we always run on).

Once we had that solved, we were still flummoxed by the behavior of the car coming out of significant, sharp turns--lots of wheelspin, even in second gear. There's no way this car has the torque to spin those huge rear tires in second gear at low speed, we thought.

Then I watched my son running, and saw the inside rear tire lifting off the ground in those turns. We found that the wheelspin wasn't too bad if we waited a bit longer to punch it, but that loses a lot of time.

What can be done to keep the rear tires planted while staying stock-legal? Do I need to get the solid Gendron bar? Do I need to spend a fortune for new shocks? Does the spending never end?

Thanks.

 

Nothing you can do while remaining in stock. The only real solution is to get a real (clutch-pack-type) LSD; the stock Torsen unit becomes an open diff above about 1 lateral g. For track days, lots of us have removed the rear bar, which allows the inside wheel to droop more, maintaining better contact with the road.

 

Definitely get the solid bar. That will help a bit. Also, shock settings can be used to some extent to alleviate it.

 

Switch to less sticky tires.

Seriously, all you can do in stock is change your front bar to something stiffer, shell out tons of cash for aftermarket shocks or adjust your driving style. I know that by being a bit more smooth, I can aleviate about 50% of my wheelspin issues.

 

Stiffer front bar! I got some wheelspin in Topeka with the Gendron Solid full stiff and 225/265 V710's. I get a little bit when I suck as a driver (jerk the car to an apex) in Packwood.

 

Hey twohoos, not to change the topic, but I tried disconnecting the rear sway bar last track day and found unacceptable understeer (Saner front bar, middle setting). Do you back off on the front bar stiffness when you do that? (235 / 255 RA-1's, for info).

 

yeah, if you dont soften the front when you soften the rear, youre dialing out oversteer.

 

Yes, definitely need to do something to compensate for the increased rear grip. I found stock suspension (w/ stock front bar) plus 225/245 RA1s was reasonably well-balanced without the rear bar.

 

Great, thanks.

 

So it appears that, in order to remain stock, I need more front bar. I understand from Bill Gendron that the stiffest bar will be 15% stiffer than the bar I have. Will 15% stiffer make a significant difference (enough to spend $145 plus shipping)?

Also, I assume that the wheel spin is a result of huge, grippy front tires. Would it make sense to experiment with increasing the front tire pressure, to slightly decrease grip? Would I lose more than I would gain?

Alternatively, should I plan, in the future, on getting smaller front tires?