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Neutral cars, BIG tires

John Boy, the Car Professor says...

> From:          John Browne <johnbro@domain.elided>
> To:            "'\"Carl Buckland\"  <buckland@domain.elided>'" <buckland@domain.elided>
> Subject:       yesterday
> Date:          Tue, 20 Aug 1996 14:43:16 -0700

> had a agreat track day at SIR. had changed the setup a little to
> make the car more neutral, was a trifle loose, could rotate it
> easily. Was great fun and we were cookin' by the end... Couple of
> times I came flying around turn 8/9 and saw the guy who runs the
> racing school there jumping up and down giving me two thumbs up so i
> guess he liked what he saw. all in all a good day.
> 
> had to share it with you.
> 
> cheers,
> john
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Dear John (I got one of those once),

I really enjoyed your article about your day at SIR.  Sounds like you 
had a great day, and learned a lot about your car. (For those of you 
who don't know John, he is a gold plated character, and one 
hell-of-a-driver. First guy to really scare me on a test ride in a 
long time! PeeKay is a seriously fast car that he drives seriously 
fast every time he sits behind the wheel).

I agree with you that before you do *anything* you need to make sure 
that your car is corner balanced.  Start with a neutral platform, 
then start dialing in the other elements.  The most recent issue of 
Sportscar (the SCCA house rag) contains the fourth installment of 
"Chassis Setup," and corner balancing is stressed.  I recently put my 
car on a set of super accurate corner scales, and was thrilled to 
find that my car (which I balanced by eye, by adjusting the 
coilovers) was really close:  with a driver:   855lbs front left, 840 
front right, 840 rear left, and 806 rear right.  

I was not surprised that you had good results by softening both your 
front and rear sway bars.  The stock sways on the M3 are too small, 
but many of the aftermarket swaybars , when set full stiff, will do 
all kinds of weird things to the handling.  I had my rears set too 
stiff at Seattle, and I had so much oversteer that I could hardly 
keep the car on the course.  It is easy to change swaybar settings, so 
I suggest that you (er, we, as I am still experimenting as well) try 
a combination of settings,  test each one, make notes, and use those 
settings for the appropriate venue.

I agree with your assessment of your springs.  They are WAY too 
stiff.  Video of your car (I will send it to you as soon as I have a 
chance) show it literally bouncing.  Also, my butt test told me they 
were stiff to the point of punishment.  Call Roland at H&R Springs,
1-805-388-8111.  I'll bet that he will have some suggestions.  The 
springs that I am using are H&R,  340 lbs front (stock is 120?), and 
380 lbs rear (stock is 340?).  They give me a decent street ride, 
provide plenty of tire compliance, and seem to hold up to very hard 
track and autocross driving.

My next trick is going to be to go to MUCH bigger tires.  I like BFG 
R1's, but they have hamstrung us by offering only 235/45/17 (too tall, 
changes the gearing on an already too tall geared car),  or 245/45/17 (which
rub on a lowered car, and have way too much sidewall 
height).  We need 235/40/17, the stock size, for proper gearing, or 
245/40/17.  Hoosier offers the 245/40, but they are HUGE, and will 
require the mod's I mention above.  I spoke personally to the BFG 
tire design guy, who says that they will offer the sizes that I want 
"within 18 months," but I can't wait that long.  So, next year, I 
will be flaired, spacered and Hoosiered.  

Hope to see you at Laguna or Sear Pt.,

Carl

Carl Buckland
1000 Boston Bldg
Nine Exchange Place
Salt Lake City, Utah  84111
801-531-6686
Fax 531-6690
E Mail buckland@domain.elided