Mechanics

REAR DRIVE SHAFT REPLACEMENT QUESTIONS

1998 Jeep Cherokee

Transmission problem
1998 Jeep Cherokee 6 cyl Four Wheel Drive Automatic 108K miles

98 XJ, 4WD stock 35 Diff, stock 231 transfer case, 108K miles.

A PO drove this XJ on salted winter roads in Mass, and it now has seriously rusted drive shaft, rear yoke, yoke nut, straps and strap bolts. The rear yoke and shaft are rusted so badly I think at some point it's gonna break. I'd rather replace it all (rear drive shaft, u-joints, rear diff yoke, yoke nut, straps and strap bolts) and not have to worry about getting stranded.

Recently I replaced the badly rusted and flattened rear springs and restored (scraped, wire brushed, Ospho'd, primed. With zinc chromate aircraft primer. And painted black) the rear rear axle and anti-sway bar. Now I want to replace the rear drive shaft, u-joints, straps and strap bolts, diff yoke and yoke nut.

1. See photo. This is the replacement shaft from a '99. This main shaft is 29" from end to end as badly depicted by the blue line in the photo. The same measurement on the shaft that is now on my XJ is 30". Measured twice on both. Question: should I abandon this new shaft and go for one of the same length OR will the ability of the transfer case yoke/shaft to slide in and out take up the one inch difference so that I can use this 1" shorter drive shaft?

2. I really need to replace the yoke and yoke nut on the diff. I have read about marking the the yoke and nut so that it goes back exactly the same way for balance. Seems to me that with a new drive shaft and new yoke, that whole process is not necessary because the new shaft and yoke will have a new and unknown balance point. So I believe the right procedure is to put it on, try it, and if I get a bad vibration, disco the shaft and begin rotating it 45 degrees until I can find a sweet spot where it will not vibrate. Yes? No? Thoughts and opinions?

3. While I have the diff yoke and nut off, should I go ahead and replace the seal? Right now it does not leak. Got the new seal.

4. When I replace the yoke and nut with new ones do I need to replace the crush sleeve? Got a new crush sleeve should I need it.

5. I have the '98 factory service manual. It calls of all kinds of special tools to replace the yoke and nut. Final question is, can a reasonably adept amateur mechanic like me do this or should I just take it to a drive line shop? What are the downsides? Do I run a big risk of screwing up the internal alignment and tolerances of the diff?
Avatar
98XJDriver
July 26, 2009.




Hi: Where do I start. First, I live in PAso I know what salt in the winter does to a vehicle. However, I have never seen a yoke so badly rusted that it needed replaced. As far as the u-joints, that is different.

As far as the yoke, do not change to a different size. You need to stay with the OEM size that was on it.

If you plan to replace the drive shaft and yoke, they both should be balanced and not require any additional balancing or positioning.

If you remove the yoke, I would replace the seal too as well as the crush washer.

Finally, if you have a repair manual and follow it, you should be fine. It really isn't that bad of a job. But make sure the yoke and nut is really bad and it isn't just a superficial problem that looks bad and really isn't.

Let me know if you have other questions.

Joe



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