I have a 95 stock XJ 4x4 2.5l NP231j chrysler 8.25 4.10 gears, 206K. It has started to give this weird vibration when i let up the gas. It happens anywhere from 15-55mph right when i left off the gas, it vibrates the rear view mirror so the cars behind me look like they are bouncing up and down. It also makes the same vibration consistently when i go over 55MPH. The rear view mirror shakes the whole time when i am on the highway, i can feel it in the floor and the seats but not in the steering wheel.

Also when i left off the gas when i am going between 35-45mph it makes a slight "whurring" sound. Slight in that it can't really be heard if the radio is on. But it only happens between 35-45mph yet i can feel the slight vibration just about every time i left off the gas. it sounds like it is coming from the rear, either t-case or rear end.

Here is what i have tried: new drive shaft u-joints, front and rear, had both driveshafts balanced, removed front driveshaft and driven it, balanced and rotated all 4 tires, new shocks, new front axle u-joints. Checked both axle pinions they looked good (don't howl and can't move the yoke). Backlash seems normal. Everything has the right amount of fluid in it and my 4wd works good. All of these things did not change the vibration/sound at all.

Anyone know what this is? Thanks, i would really appreciate it.

 

Check your joints

 

x2 on the joints.

Did you replace them yourself or was it done by a shop? If you replaced them yourself, did they move freely in the yokes with the new joint in, or did they bind.

I say joints due to having had one go out recently, the front axle, right side. Replaced it myself yesterday, and noticed that when I got the new joint in the axle and stub shaft, that there was some definite binding going on when trying to pivot the two. Mostly likely I shoved one of the ears in that the joint caps sit in, but was rushed for time so didnt get a chance to correct it right then.

It did resolve my death wobble issue, but now I have a vibration at certain speeds that I feel in the floorboards and body, but not in my steering wheel.

 

Yes, i did all the work myself. The axle u-joitns were definitely binding, but all the driveshaft u-joints seemed fine, but it still does the exact same thing.

I don't know if this is related, but i do have the "clunk" when you stop, but i am pretty sure that is the slip yoke sliding in and out, i hear it is pretty common with the older XJs.

 

check the transfer case, im having the same problem, was told from a fellow mechanic that it was the t-case

 

Seems like a dumb question, but are you lifted at all?