and how to change it on a 4th gen F-body. What happens when it gets moved forward? What happens if it gets moved back?

 

Instant-Center is a term related to a “four-link” drag race suspension system. Therefore, 4th Gen F-Bodies with the OEM torque-arm and LCAs do not have an instant-center adjustment. LCA relocation brackets are available for the F-Body OEM suspension and work well, which has some affect on instant-center (but not an adjustment). Also, with an adjustable torque-arm you can preload the torque-arm and greatly improve launches. But, nothing to do with instant-center.

Check-out this link

http://web.mit.edu/linkagedemo/www/iclinkage.html

WD

 

What changes when you go to a shorter Torque arm?

 

Unlike the LCAs or link-arms with four-link systems, the torque-arm bolts directly to the rear-end housing (solid mount, no hinge). Therefore, the length of the torque-arm would have minimal, if any effect on the rear suspension of an F-Body. Basically, the rear suspension geometry is established by the LCAs and LCA relocation brackets if used.

WD

 

The only way that you can change the instant center with a torque arm is to raise or lower the front mounting point.

 

http://web.camaross.com/forums/showthread.php?t=391537
According to this thread,...
Post #13 Third sentence..Looks like you can raise/lower and shorten the IC and according to that, it increases the anti-squat", driving the tires into the pavement.

Looks like I should have done a better search.