land-speed
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Suspension

To: land-speed@autox.team.net
Subject: Suspension
From: John Goodman <ggl205@yahoo.com>
Date: Sun, 12 Oct 2003 08:42:05 -0700 (PDT)
"Has anyone taken the time to calculate the moment arm
between the CG and roll axis?? If you are getting
chassis roll with the car standing still revving the
engine or with an under .5 G accel rate me thinks
there is some very basic design work not done yet."

Dave, the thread discussed this notion some time back.
It all surrounded the need to know where the roll
center was, how high it is above ground and what its
relationship is to CG. We got diverted a bit with
centroid axis but roll axis is a more general
description of it. Some maintained that a longer
moment arm between CG and roll axis was not harmful. I
disagreed strongly but each has to do what they think
is best. 

The longer this moment arm, the worse the car handles
in a straight line (unless you use transverse to car
centerline engine mounting). Handling problems may
increase as engine torque increases. Your description
of chassis roll under engine revving in a standing
position exemplifies torque steer. The more torque,
the greater the tendency for that torque to steer the
car off line. The greater the moment arm, the greater
the torque steer. 

Am I missing something here?

John Goodman



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