I just finished a clutch job (flywheel, clutch plate, pressure plate and release bearing). While I was under there with the drive shafts off, I figured I would be pro-active and replace all the U-Joints.
Problem one, (rear shaft) I pressed in all the new joints fine, then went to bolt the rear shaft to the diff, and the U-joint didn't fill up the space between the clips on the diff yoke. It is as though I needed an asymmetrical U-joint that measures 3 1/4 inches in one direction to fit the drive shaft, and 3 5/8 inches the other way! This really baffled me. Did I hang on the the original joints after pressing them out? No. Upon the advice of one parts person I placed two O-rings between the joint and the cup, making it wider in one direction to fit into the diff yoke. I know this isn't right, but at this point I was anxious to test the new clutch.
Problem two. I went out for a test ride, the clutch worked GREAT! But, when I get up to about 30 mph, I get a bad vibration in the seat of the pants (apparently the drive shaft). uh oh. Did I get it in properly? Did my Jerry-rigging cause it to be out of balance?
Got any clues? I feel as though if I had simply left the shafts alone, I would be merrily driving my Jeep today argh.