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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!convex!tmorris
From: tmorris@convex.UUCP
Newsgroups: net.auto
Subject: Re: Strange Suspension Problem, Need Ad
Message-ID: <82600009@convex>
Date: Thu, 5-Sep-85 13:35:00 EDT
Article-I.D.: convex.82600009
Posted: Thu Sep  5 13:35:00 1985
Date-Received: Sat, 7-Sep-85 13:49:15 EDT
References: <234@cylixd.UUCP>
Lines: 21
Nf-ID: #R:cylixd.UUCP:-23400:convex:82600009:000:1189
Nf-From: convex.UUCP!tmorris    Sep  5 12:35:00 1985


	I've got to agree with the previous response . As a former
tech. for a GM dealer , I saw quite a few cars develop those symptoms
after a change of tires . Radial tires put on older model Chevy ,Buick,
and Olds wagons were the worst offenders , with large sedans coming in
second. GM later countered with RTS ,or Radial Tuned Suspension. When
the gas crunch caused vehicles to shrink , the problem all but disappeared
as the vehicle mass/tire sidewall stiffness ratio improved.
	The radial ply counts heavily on the centrifugal force of the
spinning wheel to maintain stiffness . You can see this take effect
on a spin balancing machine , as the sidewalls pull in about 1/4"
when the tire attains the rotation equivelent to about 50 mph.
The effect is further discernible at rest , when the tires display
"Radial Squat" , making them appear like they need air.
	Unfortunately ,at 3 mph , the force to stiffen the sidewalls
just isn't there. This is especially noticeable when braking , as the
vehicle is experiencing a sudden weight transfer , and at the same time
the centrifugal force on the sidewall is suddenly decreasing...

                                          HAPPY MOTORING
.