Hey guys, new to the community and also just bought my first xj (1995 four door automatic)

I bought it for 500$ because the previous owner sheared off the passenger side motor mount bracket bolts and didn't want to fix it. only 150,000 original miles and it runs great now after fixing a lot of cooling system issues and obviously replacing the motor mount bracket.

Now the reason for the post.. I have vibration mostly noticeable in 2wd when accelerating at around 25mph and again at around 45-50 and when going faster then 50. I ALSO have a grinding sound when decelerating mainly but the it is also there when accelerating with the gas pedal depressed only a tiny bit (aka maintaining highway speeds). Also when accelerating at highway speeds there is a noticeable clunk after pressing the accelerator pedal and after letting off of it. After I bought the car I fixed a lot of things I thought COULD be making this noise but all i've succeeded in doing is narrowing it down to the drive train.

I've inspected the ujoints myself (and been told by multiple shops that they are fine. I've checked the diffs for oil, which there was. and it doesn't seem to be transmission related as it shifts perfectly. Also i have the selec trac and in 4fulltime it does get a lot better when the load is split with the front driveshaft. I was wondering if this is a common transfer case issue because I suspect that most at the moment but I really don't want to spring for a rebuild or a used one unless I can be at least more sure that's what it is.

Also when I bought the car it was on a rake (front end coils were sagging) so I took out the abomination of a lift kit that the PO had on it and replaced it with a 3" bds kit professionally installed. I thought maybe the driveshaft angle was off since it was so sagged in the front and the kit came with a 2" TC drop. That obviously did not get rid of the problem but it might have made it a little better?

Anyway all help is appreciated because I really can't figure this out and shops around me aren't super willing to work on older jeeps haha.

Thanks!

 

Maybe transmission mount or motor mounts? Is your rear axle pinion parallel, not pointing to, your transfer case output shaft?

 

I have same issue. I have done u-joints , front wheel bearings, shocks, brakes, rotors, new rims and tires, new tranny mounts.

I have same transfer case. When in full time the noises and grinding is better , when in part time the noise and grinding almost completely gone. I also get some chattering noise around 4x4 shifter. I feel like next step is to rebuild transfer case. Any help would be great

 

Sounds to me like it might be time for an axle rebuild, those sounds can refer to the rear pinion bearing. Grab the yoke and see if it moves at all.

 

Maybe your 2" transfercase drop (which is way too big anyway. Should be an inch or less. Sye is better but some people will be cheap.) when braking part of the pulley package could be contacting the radiator or something. Your engine must be tilted a ton. My transfercase drop caused leaks and creaks and noises and were the last straw for my trans and motor mounts. Worst decision I made.

 

I will take a look at rear yoke and see if there's any play. Thanks

 

#1 thank you for the responses!!!

to answer the questions,

No my rear is not directly pointed at my TC output.

also now that I come to think of it I'm not sure if the TC drop was 2" or not but I'm pretty sure it was. On that note though without the TC drop and with the crap lift installed previously the vibration-grinding seemed a little worse.

I'll check out the rear yolk and check for play as well.

I have brand new motor mounts as well I plan on installing when I get the chance and I will see if maybe that is part of the vibrate. When I couldn't get the bracket bolts out of the block (couldn't even drill a pilot hole with quality bits) I installed a brown dog offroad motor mount bracket and the oem motor mount kind of rubs the engine now so that might be causing a part of the vibrations?

If It does turn out to be the TC I'd like to spring for a rebuild with a SYE but Idk how much money at the moment I want to sink into an ambiguous issue, not having a ton of money in general haha.

Ps let me know if you figure out anything sparky, it could be both our issues have the same cause!

 

I am not following what rubs what? I have Brown Dog motor mount brackets and dealer mounts. Everything is fine.

With the lift, you should measure your driveline angles and check the pinions as suggested. The factory driveshaft in the rear has two u-joints & the angles of each need to be the same. The front is a double cardan & only requires about 1-2 degrees difference between the driveshaft angle & the pinion angle. With a 3" lift, you'd need to have longer lower control arms to achieve this, but its probably not far enough off to make a significant difference (the longer control arm adjustment is only about 3/8" longer than stock).

 

I believe it's the BDO bracket rubbing the metal piece covering the rubber part of the mount. It doesn't seem like that would really do much in the vibration portion of my issue though. The clunking and the grinding noise sound like they are coming from the middle underside/ possibly rear of the xj and the vibration at specific speeds definitely seem like they're coming from the rear.

Also thank you for the input I'll try measuring the rear DS. Is there some sort of chart I can reference once i have the measurements to figure out if they're part of/are the problem?

 

There is no way the Brown Dog engine brackets would contact the metal over bracket of the stock mount unless something is seriously jacked up. Or maybe you have a transfer case drop that's pulling the mounts? Which would still fall under the seriously jacked up category. There is no chart. The angles need to be the same so the angles zero out. One may be +3 and the other -3 so that's zero... Transfer case drops are cheap and easy but cause your exhaust to be pulled lower, your motor mounts to be pulled, .. its just a mess. You should have seen what my exhaust looked like after the PO's exhaust was welded before and after the TC drop. I gutted all of it and put in a SYE and straightened out the exhaust. You really need to identify the source of the vibration. It may not be easy. Shot carrier bearings in ther rear axle can go throughout the vehicle and may not even make their noise until loaded.... Have you pulled the differential covers and looked for metal?