89 XJ Driveline Vibration

Hello All,

This is my first post ever on a forum so.... Here it goes. I have a 89 XJ, 4.0L, Dana 30 front, 35 Rear 3.55 TracLok Non- C-clip. 115k miles.


I have been chasing my tail trying to figure out a vibration. It occurs slightly around 55-60 and increases up to 70, it feels like it's in the floorboard but some transitioning to the steering wheel. I inherited the jeep about a year ago and have been trying to get it up to snuff. I found a loose U-Joint and replaced them on the rear drive shaft but also found that it was bent and had the shaft retubed and balanced. I got new tires put on and dynamic balanced them my self to 00-00. When I was changing the rear end fluid I found pieces of the TracLok discs in the case. -_-. Ended up replacing the carrier and LSD clutch packs, kept the ring and spider gears as they looked fine and trying to save money. It had a lot of problems obviously, but this is where I'm at now with the vibrations. Definitely better than when I started but can't get rid of the high speed vibe. Front end is tight and I drove it without the front driveshaft with little to no change.


Any help appreciated.


ASE Master Tech, Ret.

Also AutoTrans. MaBad

It maybe the front axle U-Joints. Try putting it in 4X and turning a tight circle and see what happens. If they are pretty bad, you'll hear a chunk, chunk, chunk.

I jack the front axle off the ground, jam a long socket extension into the front axle yoke and kind of bounce the U-joint against the socket extension stop. If you see any kind of movement at or near the rubber seal around the U-joint end cap, your U-joint is likely bad.

Another way to spot a bad one is a ring of rust dust around the U-joint cap seal. Usually in the beginning stages of failure, when the needle bearings have dried out and the grease is gone.

A quick test for an out of balance drive shaft is to put five people in your XJ and see if the vibration goes away or changes. The change of angle in the U-joints changes the vibration. Learned this from an old school mechanic, way back when, it actually works.

You may want to check the front yoke on your drive shaft and see if the rear bushing in the transfer is worn. If the bushing is really worn it will usually mess up the seal and you'll see the leak, but it may also vibrate.

Thanks 8Mud! I'll give it a look see. I know the front does clunk or at least feels lumpy in 4wd in a tight turn but wasn't sure if that was normal from it being engaged in 4wd. The Joints look original but not loose or any signs of deterioration. She's old it's gonna be a process.

Follow up fix. Put it on a lift and found some runout at the tire. On the balancer the tire and rim were fine. Tried to clean up any rust on the mating surfaces and had no luck. Figured it must be in the bearing itself. Changed the wheel bearing today and viola vibration gone at highway speeds. Only tiny vibrations now probably attributed to the bushings being 25yrs old. Those will get changed with a lift kit eventually. Also checked the u-joints on the front axles and they seem fine. Thanks again.