2nd Gen Non-Engine/Transmission Yet another rear end clunk.

[ktmaustin]

I picked up a 1998 12 valve 4x4 98K miles today and I have an occasional clunk in the rear end when letting of the throttle abruptly.

I have until tomorrow - 2/6/04 - to back out of the deal if I can decide that there are big problems.

The rear end is Dana 70 3. 54 - the tag under the hood does not indicate that it is a limited slip.

With the brakes on we had one person shift from forward to reverse and load the converter.

The other person was looking under the truck.

It looked like the rear differential started to load and would

then 'pop' and turn another 1/10 turn or so and give a clunking noise.

It didn't happen every time but by shifting back and forth we could reproduce it.

We tried to use a helper bar in the universal to find any real play in the driveline but it seemed pretty tight.

We lowered a magnet and fished around the bottom of the pumpkin but didn't find any metal.

Out on the raod we couldn't hear any whining or other bad noises comming from the rear end.

Any thoughts on why the rear diff would start to load and then 'pop'?

Thanx

Kevin McDonald

Austin TX

 

[Alan Reagan]

Sometimes this clunking or popping sound is caused by the pinion bearing being worn or loose. When you change directions you'll hear the clunk or popping sound which is the pinion gear shifting to mesh properly on the change of direction. I had a phord that did it and it would pop and ring through the driveshaft. Sounded like hitting the driveshaft with a screwdriver blade. It was the pinion bearing causing the problem. It can be corrected easy enough but if left unattended, can cause catastrophic failure down the road.

 

[B.G. Smith]

Since you found no metalic particles in the diff. I would look at the axle ends where they bolt to the rear wheel hubs. Also can be the spline on the drive shaft. bg