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Racer's Guide to Suspension Tuning"
for every one interested in handling, especially for racing and high
Thompson, December 2015,
Using the Weight Transfer Worksheet we can work out the springs and
anti-roll bars that will give the ride rate (stiffness) and roll rate
For most models we
recommend three alternative set ups:
Performance Road - around 95 - 105 cpm ride rate
Street and Track (tarmac rally spec) - around 110 to 120 cpm ride rate
Racing - 120 to 135 cpm ride rate
The selection of
ride rate is very closely tied to the available suspension travel.
A given ride rate infers a particular minimum wheel travel. So sometimes we have to make more suspension
travel, or stiffen the ride rate and/or roll rate, or use a progressive
bump stop. A performance car will use up more suspension travel in
braking accelerating and cornering because of the greater G forces, and
therefore must have stiffer suspension.
At standard and
performance road spec, the rear ride rate will generally be stiffer than
the front, so as carry the extra loads of passengers etc. with
sufficient rear ride height. Track capable set ups will ideally be
a little stiffer in the front than the rear, generally by around only
10%. This makes the car responsive and quick on the turn in and
across the face of the corner. Similar rates front and rear help
the car to take a set (transient movements of the front and rear happen
in about the same time) Live rear axle cars may be softer than
ideal in the rear to aid traction. The decision for rear ride
stiffness depends a lot on the rear roll centre height (this will become
clear after spending some time on the WTW calculations).
So you can see the
power of the Weight Transfer Worksheet. It allows an iterative
process, trying different combinations of the available set up
alternatives, and we get closer and closer, with each trial calculation,
to the set up that will work best.
Just as important as
a suitable ride rate, is a linear and consistent roll rate. We
don't think that an anti-roll bar that is bent like a banana to miss
other components in the car, can fulfill this requirement.
We can do a "Street and Track" set up for any car and model.
me. Describe your car, and class of racing (or road use), and I can
get back to you about getting a good suspension set up for your car.
We can do front wheel drive and four
wheel drive vehicles as well. The Weight Transfer Worksheet theory
still applies. Just the objectives are different.