Hi Joe,
At 07:51 AM 1/7/00 -0700, you wrote:
>This subject has unquestionably been broached before,
Not in exactly this combination...
>but I am new to
>the list and haven't yet been privy to the collective wisdom of the
>list. So here goes:
>
>I am using the chassis and suspension from a '72 GT6 under my Spit
>Autocross car. It has rotoflex rear suspension. My questions are:
This should make for a neat autocross car.
>1. Since the front weight is significantly less (with fiberglass bonnet
>and 4 cylinder), what is the preferred front spring combination to use.
>Shorten the GT6 ones, buy SPit competition springs, or some other
>strategy?
You really need to think of the front and rear stiffness as a system.
If the car is already neutral, for example, and you make the front
stiffer, you need to stiffen the rear as well or you will induce
understeer. This philosphy is true for both springs and sway bars,
by the way. As I recall, the GT-6 springs are already stiffer than
the Spitfire ones, and if you shorten them, you're making them even
stiffer - so if you do that, you'll need to stiffen the rear a
comparable amount. For a road race car, I tend to like to use rather
soft springs and moderately stiff sway bars, while for an autocross
car where transitions are everything I like to set up a car with both
stiff springs and stiff sway bars. So, if it was me (and as I recall,
you're in D-Mod so almost anything is legal), I'd either use the shortened
GT-6 springs or something even stiffer like a set of coilovers with
custom springs and stiffen the rear spring to suit, so as to keep the
car balanced. If money isn't an object (yeah, right), I'd go for a
coilover setup on the rear too, so that you can vary spring rate and
ride height independantly to really set the car up properly. You'll
want to think carefully about sway bars too. I have found that none
of the commercially available sway bars were suitable for my autocross
TR-4, so I had to fabricate some NASCAR style bars with tubular
center sections and splined ends.
>2, I have the Competition Prep. Manual for the Early Spits and Kas
>recommends dearching the rear spring to 1 inch. Does this apply also to
>the Spring on the rotoflex rear? Or is some other strategy recommended?
See above.
>Since this is what I am working on at the moment, I appreciate all
>perspectives on the subject.
That's my perspective for whatever its worth. I'll be curious to see
what everyone else (especially those with more experience than me) has
to say.
Good luck,
John Lye
rjl6n@Virginia.edu
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