Date: Thu, 17 Jun 1999 00:36:07 -0400
Reply-To: "James S. Cohen" <jscohen@SPRYNET.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "James S. Cohen" <jscohen@SPRYNET.COM>
Subject: More Spring Info Tutorial (cure for saggy springs?)
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Dear All
I thought this excerpt from a book on performance chassis and
suspension tuning might help with the spring problems.
First, a few definitions concerning the way springs are sprung.
<bold>"Spring Load</bold> is the amount of weight it takes to compress
the spring to a given height which is expressed in lbs."
<bold>"Spring Rate</bold> is the amount of weight it takes to compress
the spring one inch which is expressed in lbs-in."
"Spring <bold>RATE</bold> does not change as the spring is compressed,
but the spring <bold>LOAD</bold> does."
"The spring <bold>load</bold> determines how much weight the spring can
support at a given height."
"The spring <bold>rate</bold> determines how much spring the will
compress as the loading increases."
"Although the spring rate will not change during the life of a spring,
the spring load can change. This is commonly called <bold>spring
sag</bold>. <bold>Loss of load, or spring sag, can be caused by a
variety of reasons, including poor metallurgy, overloading, and even
fatigue due to high milage</bold>.
If a spring has lost <bold>load</bold>, this problem should not be
corrected by changing the spring <bold>rate</bold>. If a spring has
sagged, you can get the <bold>load</bold> back to normal using several
methods. For coil springs, the usual procedure is to place a rubber
shim on top of the spring to increase the <bold>load</bold>. (These
spring shims are available through car dealership parts departments and
from auto parts stores.)"
--Chassis Engineering, Herb Adams, HP Books, 1993--
Well NOT to reignite the "shim on top or bottom" controversey of a year
ago, but I believe a shim on the bottom will do the same thing as on
top, it depends on where it's easier to insert the thing!
However, this seems to be a very credible reason to NOT BUY new springs
(SA or otherwise) to JUST fix the saggy springs.
Only change to stronger springs to improve the handling or if you (like
me) have a heavy Westy, or carry a lot of crap around (like me), or
both (er..like me).
I hope this Helps everyone.
James
PS I've still got a few SA grilles left! ;)