Leaf Spring Lift Driveline Correction Questions

[BlackNBlue-ISH]

My daily driver is an XJ, and in standard jeeper fashion, when one shock was blown, I naturally decided to upgrade all 4 and put a small aesthetic lift on at the same time. The lift of choice was a cheap 1.5" RC spacer and shackle lift. No vibrations in the drivetrain were noticed, all good to go. Until the jeep (aka just expect every problem) went on the lift to correct a check engine light and the passenger rear leaf eye broke. So it went into a different shop, and both rear springs were replaced with new. Now it sits even higher and has driveline vibrations.

Two known solutions: Drop T-Case skid, or Install angle shims to correct pinion angle.

Which method is preferred? I know the u-bolts and all that hardware was just replaced so they will all come apart without issue, and the bolts for the t-case skid are an unknown. If I went with an angled shim, what angle should I be looking at? I'm not ever planning on wheeling this jeep, so dropping the t-case isn't an issue for clearance.

[schwalby]

Can you take out the lift shackles to drop it back down a little? Or would that be too much of a drop.

[BlackNBlue-ISH]

Can you take out the lift shackles to drop it back down a little? Or would that be too much of a drop.

The new springs didn't lift it more then 1.5", so putting the stock shackles back in wouldn't work. Also, a shop installed the rear lift and disposed of the shackles.

Good thought though.

[MDSRACING398]

I might have some shims hanging around I'll look see what I have. Shims are easier than dropping case because then you need deal with linkage.

[Kurt]

Ideally you want the tcase output shaft parallel to the rear diff pinion shaft.
You can use a angle finder to measure the angles. Find the delta and pick an appropriate shim to correct.

[BlackNBlue-ISH]

I have no idea what the angles on the driveline are right now. Haven't been able to crawl underneath yet, and since its raining today/tomorrow I won't be able to until this weekend. Since Shannon is having a wrenchfest saturday, I ordered a t-case drop kit, but I'll crawl underneath that day to determine what is actually happening under there before installing it. It can always be returned. I spoke with Rough Country via online chat and the customer service guy said that a 3 degree shim should be a good starting point with that size lift.

[Kurt]

I have angle finders you are welcome to use to determine the various angles.