Jaak Lepson

Folks ... I just did my first Skid Pad and DE weekend with the PCA-UCR at Shannonville this weekend. Unfortunatly it had to end 1/2 way through the second day as my master cylinder went south ... DAMN!!!!!!!!!

Anyway, I had an understeering problem that directly related to my TOYO Proxis 4 tires and the strutbar, which we removed. Has anyone else had this problem, and if so, was the tires the main culprit? I guess I am going to have to dump these tires with only 500 KM/s on them for something better? Any sugestions? Don't want to shell out $300 CDN per tire for SO-3's!!!

Jaak Lepson

poormans9fitty1

If you want less understeer, dont unstiffen the front, stiffen up the back more. Go with wider tires or better tires in the front and stiffen the back. I think it is also better for less understeer to put less air in the front tires. Not too sure about that one. Good luck.

Jaak Lepson

Derek ... we tried almost everything we could. The problem is with the tread design. It's great on wet, snow, mud, but poor on the track!

Jaak Lepson

jc22

That would only cause understeer if you have mismatched tires front to back. That is why you should never mismatch tires. If your tires are matched the only thing you can try short of modifications is to check the alignment. Almost all cars understeer in stock form.

RPG951S

Jaak,

Can you be more specific? What year car, what wheels, which exact model tires and what sizes (F & R)
Any idea of alignment settings?
In general, one type of tire (all other factors being equal) will not understeer more than another.

However, lots of variables come into play. Despite what's written on the sidewall, a 225 Hoosier is not the same width as a 225 Yoko (for example).

Remember that you probably don't want an oversteering car, unless your trying to build an autocross car and are willing to sacrifice on-road stability. A little bit of understeer is OK (but alot is not).

FSAEracer03

Instead of new fronts, stiffen the rear like they said. You can find a new rear sway bar pretty easily I'd imagine. Get an adjustable one and dial in the back end to how you like it. Just my $0.02

Sami951

If you already tried different tire pressures, how about going with a slightly more aggressive alignment? Lose the front toe-in, maybe add a bit more camber and see how it works... I've got 0 toe-in front, 0.10 degrees toe-in rear, -1 degrees camber all around and 3 degrees front caster... and the damn thing feels almost neutral even though the suspension is badly imbalanced (weltmeister #250 springs in front, stock torsion bars in rear...)

Jaak Lepson

Raagi ... I had Markus Blazzak look at the car at the track and now confirmed it with two other performance wrenches ... It's the TOYO PROXIS 4 that is the problem. The tread block is too small and the rubber is too soft. This is a great tire for the wett and icy conditions, but under speed with the turns, it loses grip.

I had SO-2's on the car before with no problem. The only major change was the tires AFTER the ball joints were replaced. The negative camber on the passenger side is 0.9 degrees and was the same before the tire change according to a "portable" tester.

Guess I am going to have to bit the bullet and get better tires .... all this after changing the master cylinder, roters and pads. Seems the car knows when I have extra $$$ and say's .......... feed me!!!!

Thanks for the concern and comments. Car is in the sig. 1986 951 mostly stock with a few goodies. I did remove the strut bar and it got better.

Stock Tire size with phone dials!

Jaak Lepson

Empty pockets .... again.