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Re: Spit Shims?

To: WATSON@wmich.edu
Subject: Re: Spit Shims?
From: William Hartwell Woodruff <woodruff@engin.umich.edu>
Date: Mon, 10 Oct 1994 14:54:02 -0400
++> I have tried several catalogs and cannot locate shims for adjusting the
++> camber on my Spitfire.  Will any shims work or are they specific to the car
++> Does anyone know where to get them?

        I've got a half million or so hidden away in the garage.  I could mail 
a few
to you, no problem.  
        I've been following your posts, and have been meaning to send you a 
reply.  The 
caster and the camber are adjusted primarily by shimming the lower A-arm on the 
spit.  
The arm is attached to the frame with two bolts at its front and rear extremes. 
The bolts 
are long enough to accomdate a healthy number of shims between the arm and the 
frame.  By 
putting an equal number of shims in at the front and rear, you can move the 
entire A-arm
laterally.  This causes the lower trunnion to move outward in a straight path 
which 
changes the camber.  If you put in an unequal number of shims, you can rotate 
the A-arm 
as viewed looking pretty much straight down from above.  This causes the lower 
trunnion 
to move in an arc which will change both the caster and the camber.  Since 
these two
adjustments aren't independent, you can get in a situation where you can't make 
them both 
right at the same time.  Generally, this indicates some damage or extreme wear 
in the 
front suspension.
        On your car it sounds like most all the shims had to be removed to get 
the camber
right.  Then, while trying to set the caster, your suspension guy ran out of 
adjustment.  I think you'll find that one of your lower A-arm bolts has no 
shims in it at 
all.  If you are sure the suspension is in good shape (i.e. no bent parts and 
no slop), then
you probably have something sagging in your frame or front uprights.  You can 
regain some 
adjustment range by moving the upper A-arm mount outward.  Trouble is, I don't 
know exactly how
to do this.  There is another shim (the secret shim...) underneath the inboard 
front upright 
mounting bolt.  If you increased its thickness, you would move the upper mount 
outward. 
Otherwise, I don't know what you could do, except try to measure the frame and 
find out
where it is out of whack. 
        The other possibility is that your alignment person just didn't have 
enough shims 
to do the job properly, as has already been suggested.  I'd be pretty mad at 
any shop that 
didn't tell me that up front!

--
William Woodruff        woodruff@caen.engin.umich.edu
Ann Arbor MI


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