Hi,
I was one the track this weekend for the first time. It was great!
I had one problem, when I brake really hard the car gets a little bit unstable (going a little bit to the left and right). Anyone know the cause?
I have stock brakes and I cooled the brakes during 1 lap after 2 fast laps.


[Modified by EuroITR1689, 1:03 PM 7/2/2001]

 

the front gets unstable?? or the whole car? if its the whole car its normal for stock suspension, the rear of the ITR is notorious for getting light footed under brakes and long sweepers.

 

It's the rear that's getting instable I think. I have adjustable KONI shocks. Can I compensate this somehow?

 

Just curious, what type of springs are you using?

 

stock springs.

 

Just my 2 cents, but it looks like you could use a spring upgrade to something a little more "sporting oriented".
I did something similar, except that I only changed the springs, on stock shocks (that wasn't ideal either).
H & R seems to have some nice ones for the R that aren't offensive for daily driving.

 

So, you think it's caused by the combination of springs and shocks? But, can't I "tune" the shocks to somehow match the stock springs?
Is the combination stock springs/stock shocks unstable?

 

Seems the stock springs are quite soft, especially the rear progressive ones, great for compliance over rippled surfaces but apparently leads to the problem you're experiencing under hard braking where the rear end just sort of floats.

I went to ground control sleeved coilovers on Bilstein non-adj shocks 315F/500R (but over did it a bit because now the rear spring is a little under damped). Should probably have just gotten a proven shock/spring combo, but I was being just a little cheap and wanted to try it this way.

Gotta go, some work to finish in the next couple hours. ed

 

Did you have my problem with your stock springs and shocks?

 

In hindsight, probably. Though I didn't take it to the track till after I put the aftermarket springs on the old stock shocks, so I wasn't sure exactly what the problem was. Let's face it, the R is essentially a race car, but they did have to make it "comfortable" in order to sell them to the public.

Maybe this instability situation is why racers in the US go with stiffer rear springs!?

 

There is a pretty good tech article on brake bias in the recent issue of SCC that talks a bit about how that will effect handling under heavy braking.

 

With my stock suspension, braking hard from 120ish mph to 40ish mph would make the rear very very light to the point where a stiff wind would throw me off track. Coming off a sweeper, turn #2, at Pocono at 133mph and just lightly apply brake before the road course turn in, the rear snapped out violently to the right without warning. AT this point I'm going completely sideways facing the infield course but heading towards the wall.
I hit the grass and at that point I thought it was all over but when the car slid back onto the infield, it gripped and I took off. Scary as hell but looked really cool from the outside.
With the stock suspension, the rear would wiggle on me too.

I just ran Pocono with my HA's and all that is gone........ I love'em

-Nick