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Re: After fitst time aotuX. Some feedback

To: "Yuri Klepach" <civicr1992@yahoo.com>, <autox@autox.team.net>
Subject: Re: After fitst time aotuX. Some feedback
From: "Brian Berryhill" <brianberryhill@usa.net>
Date: Mon, 22 Oct 2001 12:47:30 -0500
In my experience with strut-suspended Probes (not much to adjust on
alignment), tires and how they respond to pressure are the biggest factor
when it comes to sidewall scrubbing assuming a constant car and driver.  My
Yokohama AVSi's have let me run the lowest tire pressure out of the 4 sets
of street tires I've autocrossed on.

Next is the alignment/roll stiffness, and more specifically, what happens to
the contact patch when the car sways/rolls on the suspension.  With my strut
suspension, I don't gain much outside-tire negative camber when my car leans
into a corner, this leads to a greater chance to scrub sidewalls.  Add stiff
springs and swaybars; less lean occurs, the contact patch stays more
predictable.  For double-wishbone suspensions with a good camber curve, this
is less important.  But, if you don't have a good alignment to start with,
you can be scrubbing sidewalls from the start.

Last but not least, this is an apples/oranges comparo.  You should swap cars
and see if it is driver dependent or car/tire dependent.  I could probably
go out and scrub sidewalls with my current setup, but my current driving
style has adapted to my setup so that it doesn't happen.

Since you're a newbie, don't be afraid to ask people for help or advice.
I've been at this autocross thing for 3 years and I still consider myself a
newbie.  I'm the one who gets afraid when people ask me for advice!

Brian

--
MS region autox, Nov 17-18: http://www.angelfire.com/ms2/scca/



> polyurethane bushings.  Tires: 195/50R15 Nitto 450.  I kept my front @
42psi &
> rear @ 39-40psi.  The front tire was scrubbing on more than the half of
the
> sidewall.  The conclusion is that I didn't have enough pressure in the
fronts.
> Because of that the car had a hint of understeer & I could feel the
sidewalls
> binding.

> sway bar & 19mm rear sway bar.  Polyurethane bushings all around.  Her
tires
> were Kumho Ecsta 205/50R15 w/pressures for the event being
49psi-front/45psi
> rear.  She didn't have ANY sidewall scrub & the instructor drove her car &
was
> very impressed w/the way her car handled.  Now, since my car has stiffer
> springs & softer FRONT sway bar, would that cause sidewall scrub?  Or is
it
> that Nittos have softer sidewalls?  OR, I need more tire pressure in the
front?
> And again, thanx for all your support.  We have SCCA event this Saturday &
both
> of us are going (Englishtown, NJ).
> Yuri

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