Hello all.
I have a 1997 xj country. 8.25 rear 231 tc. STOCK EVERYTHING
150k auto trans.

Im getting everything together for the lift and new tires, but before i do this much work that will probably cause enough new noises and vibrations on its own, I want to troubleshoot it to smoothness in its stock form. I feel this will make the lift issues a bit easier to track down if they rear their head.

My issue starts at around 55. I get a vibration/resonation noise seemingly coming from the front. I have no extra wobble in the steering and it doesnt seem to transmit to the steering wheel in any way at all. It is loud enough to drive the wife crazy whilst attempting to have a normal conversation. Now Ive searched this issue and found the normal "check your....." ideas. One difference is mine goes away when i hit a dip in the road or at the bottom on a hill and the suspension compresses. This leads me to dismiss anything that stays with the axle. Meaning wheel bearing,axle u joints,tires, low diff fluid, ect. Im thinking this also eliminates weights on the shaft. This leaves the ujoints either on output shaft or ujoints at diff input shaft. Looking for more ideas from jeepers as i am mearly going off of my exp with past vehicles. Thanks in advance guys.

 

I'm betting front driveshaft joints- they change angle when the suspension compresses.
Might try disconnecting the front shaft and seeing if the noise disappears.

 

Im leaning towards these as well. From what i read the output shaft u joints are a common issue as well. I think ill pull it this weekend and give er a makeover.

 

Update. The front driveshaft slip yoke has ALOT of lateral play. It has a grease zerk so I decided to hit it. It took ALOT og grease before it started running out of the end down by the axle. When I got it greased I checked play and it has nearly none now. I'm assuming the shaft is bad though and will be replacing it.