oversteer at track

[stuntman]

Okay i'm back from 3 straight race weekends.

L8apex:

So you are running 205/50-15f and 225/50-16r tires correct?

You said they were Avon "race" tires. Can you tell me exactly what model tire you were running on?

Finally, what spring/shock setup are you running? Do you happen to know the spring rates?


It sounds in general that you have the front of the car pretty stiff with the shock/aftermarket swaybar. It also sounds like you have a pretty soft rear end in attempt to allow the car to squat and get more grip when you apply throttle.

My first question would be: does the rear of the car roll alot compared to the front? With all of the above listed tying the front of the car down, and the rear being that soft, does it feel like the rear of the car is rolling around more than the front?

I would try lower tire pressures in the rear. Depending on what tire you are running on, if youre coming in at 35f/37r, try going down to 32psi rear.

It sounds like your LSD is working, as you said, if it wasn't, you would get a 'one-tire-fire' and it would understeer.

With what I know at the moment, it sounds like the stock rear tires can't take the track abuse especially with the upgraded suspension.

FWIW, back when my car had the stock 205f/225r tires on it, I could get oversteer easily, even at turn in -on freeway off&onramps. That stock setup had way too much oversteer, but it also had it an turn-in as well as exit, which you were not having problems with at turn-in (possibly because of your aftermarket setup, the front of the car had more platform and was stiffer to prevent that oversteer).

 

[L8apex32]

Stock tire size, 205/50/15 and 225/50/16.
My springs are stock.
The tires are Avon race tires, called the Tech RA. http://www.tirerack.com/tires/tires.jsp?tireMake=Avon&tireModel=Tech+R-A

Re front vs rear roll... you can't tell. Standard cars have a front roll center and a rear roll center. The car rolls about the line between these two points. Unless I changed my suspension arms or ride height, these are the same for all NSXes. Changing stiffness front to back (ie springs, sway bars, etc) doesn't affect the roll centers... just the amount of roll. But, my roll is pretty nice. An NSX starts out good and I'm a little stiffer so I roll a little less.

If we had a situation where the rear could roll too much, that would require the chasis to flex (front not rolled, rear rolled) - but I think that would show up in tire temps also. My tires have decent temps (not too high and fairly even).

I will try less tire pressure in rear. Or, maybe I'll try more. I did get even wear for my last set which was nice, but an experiment here is called for.

Maybe I'll sell one of my stock sized sets of Avons and go for a wider rear set. Maybe that would help some. I could also go for an even stiffer front sway bar.

Anyone want to buy a new set of Avon Tech RA tires in the stock rear 225/50/16 size? Want to buy a whole set - front and rear? In stock now!

Anyone want to sell a used front sway bar stiffer than the Dali race one? (The Dali bars go street, race, track as I understand it so there is a Dali one that is stiffer. I think mine is .875" diameter.)

Thanks for all the help guys and gals.

 

[stuntman]

go to wider wheels and tires. Not just tires. You do not want a wide tire on a narrow wheel.

17x7.5 or 17x8 front 215-225f
18x9.5 or 18x10 rear 255-275r

try that.

 

[docjohn]

Many of us go with 235/40/17,,front and 275/40/17 rear on any lightweight wheels that fit such as ssr comps.You must be able to put up with the rubbing that those 235 fronts will do to the inner fender well at 3/4 lock.Please search our forums on the many threads about upsizing wheels and tires for the track.Lots of us use ra1, you are the only person so far posting using avon.