netvvork

New engine mounts. New trans mount. Fully rebuilt rear end with all bearings involved being new. Revving the engine in park is smooth as silk. When driving and giving it the beans, there is a harsh vibration increasing into the higher RPM with an oscillating quality. Some guy said it was a thing called axle wrap that happens under high torque. I do not have a lift or anything. The jeep is fully stock. I was thinking maybe the drive shaft is out of whack or something. Any ideas?

EDIT: All new leaf springs, shackles, u joints, and shocks as well.

PatHenry

If it's axle wrap, then it might be time to replace your leaf springs.

I'd do a double check on all the mounting fasteners (motor and tranny mounts) and make sure they're all torqued to spec. Also check your spring bushings and make sure they're in good shape. While you're at it, double check the u-joints on the driveshaft.

There's a lot of low end torque from the I6, but I've never heard of anyone experiencing axle wrap issues - and at stock height and stock engine?

netvvork

Forgot to mention that the leaf springs, shackles, and all 4 shocks are new too. All of the symptoms above were there before I did any of the work. I was sort of hoping to smooth it out. I dont regret replacing all that stuff because its a low miles xj and I want to make it cherry. If anything, this helps me keep my foot off the gas a bit. Its just annoying.

gat

It may be an issue with the rotation of wheels. How are the bearings in the read and ball joints in the front. Check to play at the wheels and tires in all directions.
Also, test whether it happens with and without the front driveshaft

netvvork

All bearings in the rear, to include axle and pinion, are new. Front suspension, however, is a bit loose and clunky when going over bumps and such.

PatHenry

I wonder if it is actually a flavor of DW that you're experiencing if the steering/suspension stuff in the front is weak and the rear end and diff is super tight.

Do you have the rear sway bar or not?