Thank you for all the replys guys. Sorry I have been out of town for Christmas and havent had a chance to work on the jeep

I will check the exhaust hangar and various cross member supports to make sure they aren't the culprit.

Oddly I just put 33's on it up from the stock tire size and the noise doesnt seem to be as noticeable..... I'm thinking its just because the road noise of the 33's just drown it out now

 

Hey OP. Tuning in here with the same problem. Did you ever discover what the problem was?

Hope all is well!

 

To be honest I never fully figured it out. My trans mount was completely worn out so I replaced it and it helped alot. I'd check to make sure your exhaust isn't hitting the transfer case crossmember. That's where most of the rattle at idle was coming from.

However if I'm coasting then step on the gas you can sometimes here a thunk sound coming from the transfer case area as the driveshaft and transfercase come under load. I plan on taking a look in my transfercase to see if there is slop in the gears or chain when I do my SYE. This probably won't be for another few months though.

What symptoms are you experiencing

 

I am experiencing a knock (singular knock) when clutching, and shifting into gears (1st,2nd,3rd) almost like a shift in alignment when letting out the clutch to put the load on the driveshaft. However, It's loudest when shifting from neutral (stopped) to 1st (moving forward) and neutral (stopped) to reverse (moving backward)

I have replaced my upper control arms + mounts (thinking it was a front end issue) and my Transmission mount, but have since found its in the transfer case area.

Cant be the exhaust hanger because I have an exhaust that does not use the hanger.

 

Im not sure. Maybe gear or chain slop in the transfer case? I'm not to familiar with the transafer case/transmission. I haven't opened mine up yet to take a look either.

Let me know if you figure it out. I'm curious to know what it is

 

So I figured it out a couple days ago.. after replacing the motor mounts, trans mount, upper and lower control arm mounts, and tightening pretty much every nut and bolt on the drivetrain. Long story short, the issue ended up being a bad U-Joint bearing that had clubbed itself, and was no longer rounded. It didn't look bad, but I figured what the hell. Already came this far.. lol

From what I discovered on the clunking noise, this issue is caused by bad U-joints, and a dry slip yoke on '97+ XJ's.. Pre-'97 has the slip-yoke lubed by the TC, and doesnt need grease.

The issue is easily fixed with a couple of U-Joints, some bearing grease/anti seize, and by removing the driveshaft.

It took me about an hour in total to remove the driveshaft, pound out the U-Joints, replace em, and to put it all back in. Took it for a spin, and drives like new.

Good news is, I ended up replacing a bunch of worn out stuff trying to fix this, and now my heep drives better than ever! Hope this helps!