I have a 94 XJ and just installed a 4.5" RC lift kit. I have a front drive line vibration only in 4X4 and I cant remove the front drive shaft when the front wheels are off the ground it wedges the drive shaft between the front diff and the T case I have to have all 4 wheels down to remove shaft and most of the drive line slack is used up. I installed the 1" TC drop that was supplied in the kit. Could the TC drop be causing the problem by raising the front pinion angle? The drive shaft U joints and CV joint is good and confirmed by a drive shaft shop. I have had the front end alinged and TC output shaft bearings checked and Ft. diff brgs checked. I drive at higher speeds in 4WD 30 ish MPH on slick roads in the winter other wide it would not be a issue. Thanks for any help.

 

I don't understand how it "wedges" when the wheels are off the ground. Do you mean when flexed, and the driver side is stuffed? Because if you mean when it is up on a lift, then the shaft is getting stretched out. Anyway, if you are almost out of space in driveshaft slip, you need to address that anyway. The difference in yoke angle at the Tcase on account of the drop kit could be contributing, as you suspect. You may also need to look into how much angle your CV can handle versus where it currently is. It is hard to say if you will be able to get rid of all the vibes with the T-case drop and lift. If the joints are good, yokes are good, CV is in good operating range, then the yoke angles are all that is left to investigate Don't forget the front diff pinion angle should be adjusted upward to compensate for the lift. If you do not have adjustable uppers and/or lowers, this could be difficult.

 

Front U joints mabe? mine are gone and i can feel it. also check your brake lines with the rc lift i just did mine and the brackets dident do anything almost snapped my fronts first time out.

 

T case drops will put more of an angle on your front shaft but not usually enough to hurt much. If by letting the front wheels droop your shaft is fully colapsed then I'm guessing something isn't right, like the control arms are too short.