2015 C7 serious problem
Tech Contributor
Joined: Oct 1999
Posts: 41,044
Likes: 9,808
From: Charlotte, NC (formerly Endicott, NY)
This is a shot in the dark since I don't know if rear caster could cause your issue. I know it can cause bump steer which is a change in the rear toe settings under compression. Does your dealer have the tools to make sure rear caster is measured and set correctly? If not that could be part of the problem. Your description sounds like a thrust angle error but if they have realigned the car several times and the thrust angle is 0 then maybe the rear toe is changing under acceleration due to caster irregularities.
This can be a frustrating conversation since a lot of dealers don't have the tools and a lot of mechanics say there is no rear caster adjustment. However, GM lists it in their Service Manual alignment specs. One of the problems is most mechanics probably read the specs on the alignment machine and don't bother reading the FSM. Since the alignment machine can't measure rear caster they don't know it exists.
Here is a link to a discussion about the tool.
http://www.teamzr1.com/ubbthreads/ub...at&Number=3592
Bill
This can be a frustrating conversation since a lot of dealers don't have the tools and a lot of mechanics say there is no rear caster adjustment. However, GM lists it in their Service Manual alignment specs. One of the problems is most mechanics probably read the specs on the alignment machine and don't bother reading the FSM. Since the alignment machine can't measure rear caster they don't know it exists.
Here is a link to a discussion about the tool.
http://www.teamzr1.com/ubbthreads/ub...at&Number=3592
Bill
Last edited by Bill Dearborn; Apr 13, 2016 at 01:21 AM.
Melting Slicks
Joined: Sep 2005
Posts: 2,670
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From: merritt island fl
C1 of Year Finalist (stock) 2019
2016 C1 of the Year Finalist
2015 C2 of the Year Finalist
What are the actual alignment measurements- not the specs, the actual measurements of your car?
Team Owner
Joined: Feb 2013
Posts: 22,598
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You sure it's not the roads? You go drive around in a flat parking lot? The C7Z I'm driving will jerk to the right once in awhile, but most sprots cars with huge sticky tired do as they tramline and follow ruts in the road etc.
