I have a 92 xj 4.,0 auto 4x4.... it has a driveline vibration that shows up around 45mph... I took it to a shop that put it on a lift and ran it .... they used a stethoscope and determined it was the transfer case .... they said they thought it had a bad bearing ...... my question is what transfer cases will work with my jeep ... it has a np231 in it now .... the jeep has 163,000 miles on it and is stock..... I have found np231 transfer cases for sale but afraid of getting something that will not work ..... I can remove and replace it ......In need of some good advice

 

I have a '93 Grand Cherokee.. same xfer case as yours. I too had a drive line vibration which was narrowed down to the xfer case. (By a professional mechanic) As I was removing it to be replaced, I discovered a very worn out double u-joint. It seemed ok "on" the vehicle, but removing it showed it to be really bad. Replaced it and the outers for good measure. No more vibes!
I'd double check your u-joints just to be sure. It was a double cardan joint. Two u-joints in one kinda deal. Sorry I have no real answer, just advice. Good luck!

 

i hardly doubt it's a bearing inside your transfer case. those are pretty stout and only has rotational shafts through them.

take the advise of the double cardan u-joints. i would start there.

 

Thanks for the advice.... u joints makes sense ..... They will be replaced in the near future and results posted ...

 

Yeah, that's good advice. Not expensive and not difficult. It that's not it... well, you didn't spend much time and effort, and it probably was pretty old anyway.

 

Try driving with the front driveshaft removed to see if that cures the vibrations. In addition to worn u-joints, the slip yoke on the driveshaft can also wear out and become loose which creates vibrations. Get under the Jeep and try wiggling the front drive shaft - if there is up/down play then the slip yoke may be wornout and you may need to buy a new shaft.

I have been living with a vibration from the front driveshaft at 70-80 mph for the past 2 years. I think the only cure will be installing a free-spin hub.