MI_Offroad

Here's problem:
Drivetrian vibrations that start around 35+ then get really bad around 50 then get less after 70, but don't completely go away.

Started after I made a turn about a mile from work on Fri. Drove home after work thinking locker failed because it happened on a tight turn.

Info on truck:
2001 XJ
4.5" RC short arm lift w/drop brackets
Advance SYE
Woods Driveshaft
Serious 1-ton
RE dbl shear track bar
Aussie locker
Shackle relocate
Urethane bushings in rear
and so on...

It worked fine for the last 3yrs, then BAM! All vibratoins feel like they are coming from middle to rear. I feel nothing in the steering wheel or the floor boards at my feet under the pedals.

What I've done so far:
Pulled rear dif cover - everything looks great
checked all driveshaft U-joints, F & R - fine
Checked all fluids - fine
regreased all fittings F to R - done
Put on brand new 35" KM2s - had the excuse

STILL VIBRATES!!!

I know all driveline angles are good, because it has beeen fine for 3 yrs.

Has any body had a tranny or tansfer fail, and did it feel like this?

AndyB

Sounds like what mine was doing with a loose sye yoke nut. But mine would only vibe under load. Coasting downhill it would go away. Might want to pull the front ds to see which end has vibes.

XJ-92

Check to see if the weight on the rear driveshaft has fallen off.

schirm

It's one of your drive shafts or both. Could be your CV joint has internal rust, could be u-joints or it could be a rusty slip yoke. It also could your drive shaft got knocked out of balance. And unless you have lock out hubs then either drive shaft could be your problem. Your t-case or tranny failing would cause much worse symptoms.