I have a '97 XJ that makes a strange vibration when letting off the gas at 40-60 mph. The noise only lasts for 1-2 seconds max and is pretty consistent. I do have a bent RR axle shaft as stated in a shop invoice when I bought the Jeep. Could the axle shaft be making this noise? I plan to replace the axle shaft in a few days. The guy at the shop told me that it is safe to drive as long as it is not leaking. I am planning to go out of town this weekend about 300mi worth of driving.

Thoughts?

Thanks!

 

Look here:

And also inspect your engine mounts.

 

Might be the rear driveshaft

 

I've checked the driveshaft and there is minimal play. The front driveshaft ha more play...

 

Update: After doing some more driving I've decided that the noise happens when I engage/disengage the gas pedal at high speed (40+). It also doesn't do it every time.

 

I would certainly suspect a bent axle shaft as the cause. A bent shaft will also wear out the inner and outer bearings.

 

Check the easy and obvious first. Are your lug nuts tight? If you just had the rear wheels off and didn't re torque them after they could have loosened and cause a vibration/noise when a load is removed from the drive wheels.

 

^ All good ideas but, the most obvious is a verified bent axle shaft as stated in first post.

 

^this

I'd still jack up the front and spin the wheels to see if the hub bearings aren't grinding when you take off the drive load.

Spin the wheel and listen

Wiggle the wheels with hands at 12-6 and 9-3 and check for play

 

All this conversation and conjecture is great, but some noggin pokin' needs to be done on the OP's end........