Hi everyone - I've got a 91 XJ Laredo with 222,000 miles - I noticed that it has a severe vibration at 55mph - I got under it and realized that the rear drive shaft connection at the axle was rattling around inside of the bolt down straps - On either side of that axle pinion yoke - there are raised portions that seem like they should be seated against the end of the caps of the U-joint to keep it centered - the U joint cap was no longer being held on one side so it was allowing it to shift almost 3/16" inside the pinion yoke.

I went and got a new U joint - pulled the drive shaft and pressed in the new U Joint - Went to reassemble and the U joint caps still don't sit against the edges of those guides on pinion yoke leaving about 3/16 of slop with the U Joint being able to move back and forth in the caps if I tighten the straps down with the caps all the way pressed against the raised portions on the pinion yoke.

Thoughts? Do I have the wrong U joint? Are the caps supposed to sit against the outside edge under the straps and the U Joint is supposed to have that freeplay in the middle to slide back and forth? Does any of this make sense!?!

Thanks for any help anyone can provide!

 

No, there should not be slop between the universal cap and the pinion yoke.

Re the universal: the clue here is that you "pressed the new universal into the driveshaft" if it was a press fit it's probably the correct universal.
Sounds like the pinion yoke is shot or it's the wrong axle for the driveshaft

 

That was my thinking - If it pressed into the shaft without any issues and allowed the snap rings to fit back in the grooves - the Universal is the correct size for the shaft and should match the pinion yoke. The drive shaft is original to the jeep, as is the rear end - I literally have a 3 ring binder 2" thick of all service records and haven't come across anything driveline related.

Out of curiosity - is there a spec anywhere to what the measurements on the pinion yolk should be? Is it possible that the yoke opened up that 3/16" to 1/2"? That seems like a lot of movement for a cast piece like that - but I'm also not an expert.

Now - next question - Replacing the pinion yoke - What's that look like? I'm assuming there is a pre-load that has to be maintained when put back together. I'll look up some videos - but if you've got some pointers - I'm all ears.

Thanks!

-Will

 

Just for laughs you might try replacing the hold down straps but if the thing has been that loose that long the yoke is probably shot.

The process for replacing the yoke is in your shop manual

 

BTW
if that universal is that loose in the yoke you really don't want to be driving that thing until it's fixed. If the end of the driveshaft gets loose at 60mph many bad things will happen.

 

Picture might help here so we can better understand.

Its possible the previous u-joint may have been spinning in its seat on the yoke causing wear on the small raised guides. I had this happen once. One of the guides was completely gone. I had to replace the yoke. Measure the distance between the two guides and compare to the specs for the u-joint to see if its wrong.

 

Sounds like your new u-joint is the wrong size. The caps should fit snug in the yoke with no slop. The raised lips on the yoke are what the caps butt up against. If there's a gap, the joint is too narrow. Double-check the part number you likely need a different u-joint. A parts store can confirm the correct one for your year and model.