Drive shaft vibration

[gsr7286]

96 jeep cherokee se. 3 inch blocks in front coil springs. 2 inch lifted leaf springs with 1 inch longer shackles. Drive shaft vibrates. Assuming my pinion angle is off and have to shim the rear. What do I do? What do I need?

[downsy]

Actually you'll probably need a T-Case drop or a short shaft kit. You can check out the pinon angle with a cheapo angle finder from Home Depot or Lowes. IIRC it just needs to be the same as the T-Case output angle.

The ultimate fix would be to put a Short Shaft kit in the T-Case. The cheaper route is to install a T-Case drop.

[abebehrmann]

Awesome writeup by 4.3LXJ http://www.xjtalk.com/showthread.php?t=7299

[gsr7286]

Thank you for your help. What would be the pros/cons between shimming the crossmember to drop the t-case vs. getting the short shaft kit?

[downsy]

T-Case drop
Pros- cheap, easy to install
cons- lowers your ground clearance

Short Shaft Kit-
Pros-You can drive your Jeep with no rear driveshaft, your drive line gets longer so easier to keep from vibrating, it's stronger generally speaking, keeps your drive line tucked up in the Jeep.
Cons-Expensive (need a new rear drive shaft), semi-complicated to install if you aren't mechanically inclined, requires removal and splitting of the transfer case unless you use the "Hack'nTap" kit.

[OrangeXJ]

Chech your U joints if you have not done that all ready

[downsy]

Chech your U joints if you have not done that all ready

Good idea. Much cheaper than the Short Shaft Kit haha.:xj-black:

[catfish51]

By using longer shackles you changed the bend of the rear spring which in turn made the pinion driveshaft yoke tilt upwards.This changed the angle which as you said you already know must match the driveshaft yoke angle on the transfer case.You have to measure the angle of the yoke on the transfer case ,then measure the angle of the yoke on the rear diff.You're going to probably find a 6 degree difference with a 3 inch lift.Many off road parts companies sell angled shims to put between the rear diff spring perches and the spring under the U bolts.This will tilt the rear diff which then should be the same angle as the transfer case yoke.Like someone already mentioned you can get a cheap angle gauge from harbor freight or possibly home depot.If you don't get those angles to match or at least be within 1 degree you are going to get vibration and blew up u joints.
This is one of the cheaper easier ways to correct your problem the others mentioned are also very good but more costly.I don't think a set of shims will cost you $30.00

CATFISH