I recently purchased a beautiful '85 CJ7 (258/T176/D300/D30/AMC20 and my very first non-XJ Jeep). The PO installed what appears to be a 1.75" shackle lift with 31's. Unfortunately, funds are a bit tight until I recover from the initial vehicle purchase. While I am not a fan of the shackle lift and will eventually install a proper 2.5" spring lift, fixing the caster angle inexpensively is priority right now.
My current caster angle is 0.7 degrees negative. So, I need a 6 degree shim to be within factory specifications.
Without getting into a debate about the safety of axle shims in general, is a 6 degree shim pushing it? Seems like it will be a pretty thick shim. Should I go with a 4 degree shim and just get in the ball park or go ahead with the 6 degree shim? Obviously, I am referring to a steel shim which is incorporated into the leaf pack via the center pin. I will also be replacing the u-bolts.
I realize that repositioning the perches or rotating the knuckles are better options for a permanent solution. However, as I eventually plan to replace this somewhat sketchy shackle lift, I need something easily reversible and inexpensive.
I do not believe that shims are inherently dangerous when incorporated into the leaf pack; however, I do feel that there is probably a limit to how thick one should go due to altered forces on the center pin (it will now be "clamping" an angled surface; I have seen people shim both sides of the spring opposite one another to alleviate this abnormal force). My question relates to whether or not a 6 degree shim up front is approaching or exceeding this theoretical limit.
In short, assuming you think degree shims are safe, do you think 6-degree shims are safe?
Last edited by josh86k10; 10-22-2010 at 05:53 AM..