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Re: rear tube shock conversion

To: Ryan van Luchene <Ryan.van.Luchene@celeradiagnostics.com>
Subject: Re: rear tube shock conversion
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 28 Jun 2004 15:30:02 -0400 (EDT)
Hi,

Ryan's experience reminds me about making changes _any changes_ to the
suspension on your car is not merely a matter of bolting things on - at
least usually.

Instead, you need to do a few things to make sure what you have installed
hasn't introduced some new problems.

For example - I lowered the front of my car. I lowered it a LOT. Before I
slapped the wheels on for a test drive, did the following. With the spring
out, I ran the suspension from full droop to full compression. First I
checked for binding. Once that was done, I installed a tire/wheel and ran
through the full suspension range. I then cocked the wheel to full lock
left and ran the suspension through the motions and then turned the wheel
full lock the other way and ran the suspension through it's full range.

Why do all this work? Well, I found out that the tire would interfere with
the fender at the top of the wheel arch at full compression. This would
have resulted in tire smoke (best) or a sliced tire had I not checked.

Why am I relating this? Well, it sounds like Ryan's frame problem was
probably due to the new shock bottoming before the rear suspension got to
the bump stops. This would introduce sudden shocks (sorry - pun intended)
to the frame and the result would be the observed cracks.

This is why it is so important to test these mods before you use the car
on the road. And it's not worth pointing a finger at the vendor, because
they have no control over how you install/test the product.

Case in point - I mounted a new set of slicks on the race car. I also
installed a new set of Panasport Ultra Lite wheels. Turns out that the
wheels had a different offset than the wheels I was replacing. I found out
the hard way that the tire was rubbing on the upper a-arms at full lock. I
was very fortunate that I did not completely ruin the tires. Net cost?
$360+ for two slicks that got the sidewalls slashed. :-(

Bummer.

Caveat Emptor takes on new meaning when you are dealing with cars 30 years
old!

rml
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