some of you may recognize me due to my previous postings about my oversteer problems in the "tire and wheel" forum.....

background:

i have 18" wheels, KG/MM DR21 lowering springs, stock shocks, and a digrappa x-brace. i just put 18" OE Porsche S0-2's (N1) in the front 225/40/18 and OE Mercedes S0-2's (MBZ) in the rear 265/35/18.

i had to go with the MBZ rears due to my lowering of the car as the MBZ 265's are narrower than the matching (N1) Porsche 265's.

prior to this tire change, i had 18" S0-3's all around and the car had neutral handling.

now, however, i get a tremendous amount of oversteer and was wondering what i could do to counter some of the oversteer......

on a side/positive note, the fronts grip like a bulldog and if i could only figure out a way to increase rear grip, i would be set!

my thoughts:

1. remove x-brace.
2. fiddle with tire pressures.
3. change rear sway bar (bigger/smaller??).
4. bite the bullet and ditch the MBZ rears and get the N1 rears (i would have to raise my car somehow, though)
5. re-do/change/adjust alignment (more/less camber, more/less toe??)

i'll be the first to admit that i'm not overly knowledgable about the "cause and effects" of suspension set-ups and geometries.

any help would be appreciated.

thanks in advance...

 

You can achieve pretty amazing changes with fairly mild adjustments to the tire pressures...

I had some bad over steer when I went to 225fr and 245rear R-Compound tires for the track...

I started out at 38/34 pressures... I found that dropping to 30 in the rear, and ~34 in the front made the care sooo much more stable.

Now, I'm NOT saying those are the pressures for you (and you really want to check the pressures after pushing it/retest/push it again, so the tires are HOT)...

But "in general" you want more traction in the rear, and "less" in the front, so you want some bias (difference) between the front and rear pressures to achieve this... Typically more in the front and less in the rear for an over-steer condition...

I know thats much help, but its the best I can offer.

-- Aaron

 

Your best bet is an adjustable front sway bar. This will allow you to dial it in just the way you want it. Last I checked, Comptech was the only manufacturer, and it wasn't cheap.

 

btw, i'm at 30 psi (cold) at all 4 corners.......

 

Then raise your front pressure, and look at the edges of the rear tires.. are you touching them? (eg. when auto-xing or cornering hard it should show wear to the edges)...

If I were you.. I'd consider starting around 36 front, 33 rear... and work down in pressure from there... (I don't really know your setup or how those tires handle, some people run 40/34 at the auto-x... so each tire is different)...

but I do know this: Its easier to remove air from the tires each run than it is to add air :-)

-- Aaron

 

Run a seach on the Genderon Front sway bar. Thats probably your best bet. Autox guys have a simlar problem when we play with the tire stagger. A front Sway bar will Solve your problem.