Major Vibration at Speed. Causes??
 

I have a 2001 XJ all original. Well, until lately. Prior to my lift, I noticed a vibration at about 50 mph and above and just a noisy, squeaky front end. Just put a 3 inch lift and the vibration is considerably worse. While installing the lift, I noticed the right front wheel had some play in it. Possible wheel bearing issue? Since this Jeep is all original, I went ahead and ordered some Timken wheel hubs for the front in hopes this will solve the vibration problem. But I'm concerned the vibes may be the drive shaft. I checked the u-joints for both front and rear shafts and all appear solid. So, anyone with a similar issue? Is it the shaft or the wheel hub/bearings causing the vibration? I hate to throw money at problems before I hit a bullseye.

Vibrations that develop around 50mph, and especially those that are more prominent when under load (accelerating, going up a hill, etc) tend to be u-joints in the drive shaft. Particularly the rear drive shaft. The u-joint does not have to have play, or be obviously bad from external inspection to be bad (they can get dry inside, or start chewing themselves up internally before showing any signs of external play. If you had one that was starting to go bad before the lift, it will almost certainly be even worse after the lift. Even good u-joints sometimes complain right after a lift because they have rotated at one angle for so long and really worn into that regime, then the angle changes (even if just slightly) and they have to "wear in" to the new angle over the next hundred miles or so before they smooth out.

I only lifted about 1.5", and my rear shaft u-joints (which were pretty new at the time) complained for about 100 miles - then settled/smoothed out.

If it has been a long time since you have serviced the rear shaft u-joints, I would simply do them. Right after a lift is probably the best time. The job is relatively inexpensive, and does not take much time at all.

Thanks jordan96xj! Any particular brand to go with?

I went with spicer, and prefer the serviceable joints with the fittings in one of the caps (easier to get to than the type with the fitting on the join body).
The following is a link to the specific product I used.

One other point to look at is the sliding yoke in the front of the shaft. If the splines are worn at all, the increased drive angle can make it vibrate. You can pull the front shaft and drive it to see if that's the culprit.

What's your drive shaft angle? I'm kinda in the same boat now having lifted only a couple inches but there's some vibration that could be addressed. I'm going to shim the axle about 6 degrees cause right now it looks to be about 13 (which seems like a heckuva lot with just a 2 inch lift).

Perhaps I should measure it on a flat surface instead of the hill I'm on. It's tough to try to compensate for all the angles.

You could also drop the transfer case a little:

https://4x4.fatbobsgarage.com/jeep-c...yABEgLruPD_BwE

Rusty's looks a cheaper:

https://www.rustysoffroad.com/rustys...kit-xj-mj.html

but you get the idea.

Hell, just make spacers from tubing or bar stock. WAY cheaper. LOL!

Thanks y'all! Pulled the front drive shaft off and took it for a spin to about 90. No vibes and I could actually use my mirrors.
With that being said, it's a drive shaft issue.
One question I have...... Is it possible the front differential has an issue? I didn't feel or hear any noise or vibes when I drove it without the shaft attached. There was some minor play in it (maybe an 1/8 inch) before I pulled it, but thought that would be normal as the 4WD wasn't engaged.
The shaft seemed tight and the joints didn't look or seem trashed.
Thanks again for the assist!