The shims for the rear control arms are used to setup the toe-in on the rear
wheels. It isn't much (1 degree if I remember right).
A lot of people have changed rear springs when they didn't have to because the
toe-in was gone. Sloppy bushings will play a factor here.
If you consider the car moving forward with both wheels with toe-in, the wheels
will tend to move towards the centre and lift the car. When it moves backwards,
the wheels tend to move outward and lower the car. Before anyone decides to
change their rear spring, get the rear alignment checked first. You may save a
few bucks in the end. Of course, I changed out my spring before I learned this
little tidbit. But the spring probably needed changing anyway as the PO had put
helper springs on it.
Vic Whitmore
76 Spitfire
Thornhill, Ontario
A666K@aol.com wrote:
>
> Hey all,
> --Just got done with a very quick suspension rebuild. New polys, trunions,
> bjs, spax, etc. Now its time for the alignment shop, any suggestions as far
> as what numbers to aim for? This is for a daily (hard) driver+ weekend
> autoxer.
> --Just out of curiosity, how does shimming the rear control arm achieve
> geometry changes? Doesn't the rear spring force everything to stay in line
> with it regardless? Also, when playing with the rear tow settings, does
> positive tow encourage the rear to go lower while the car moves forward,
> higher in reverse? If so what were the factory tow settings when it came to
> rear tow? I would love to hear your settings out there!
> Have a great weekend!!
> Avi
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