Save the U-Joints!
Contributed By: James Jezak
Recently I was driving my 78 Cherokee w/ QT to work and was noticing a noise coming from what sounded like the passenger side of the transmission hump. It sounded like when you're in a commuter airplane when they're testing the engine before flight. The noise rippled through the body. (Please don't be the transfer case!) It happened only at certain speeds with power applied. When I parked I revved the engine in neutral and there wasn't any noise so that told me it had to be the drive train. That evening, the possibility was narrowed down to the front drive shaft.
Since the shaft was nearly grit free from the tranny fluid dripping off a temporary transmission cooler line onto it, and I personally had only gotten around to greasing the very front u-joint I knew that one of the joints by the CV joint was going out. Although I've done dozens of u-joints in my jeeps before (especially the CJ-7) I have never had the 'pleasure' of doing the front drive shaft off of a Full Size Jeep. This may/may not apply to FSJ's with the 20/228/229/208 etc. transfer cases since I haven't been under one of them. Here's my advice to you if you have the original u-joints in yours like I had in mine. TAKE IT TO SOMEONE ELSE. Just kidding. With a little perseverance and a lot of time you can get it done, have a reliable front end, and save some bucks.
NOTE- the CV ball and half end yolk will probably come off after this u-joint. Don't loose the needle bearings or the spring inside of it! Check the seal around the ball- mine was shot so a new inner CV section was taken from a spare shaft I had to replace it.
The same process goes for the other joint on the CV. The one at the front of the drive shaft is the easiest. After everything is disassembled clean it up thoroughly, paint it if you want, and take five.
Take your freshened drive shaft, lube the yolk holes for the end caps and place the inner side of the yolk down on the wood so you can tap the caps in just a little bit. Insert the new u-joints end cap into the front-end outer-side hole of the shaft. (make sure the needle bearings inside don't get lost or misaligned because they only come with minimal grease on them) I used regular zerk cross fitted joints on the front two and a flush end cap fitted zerk on the rear to ease future maintenance. Tap one in until the seal starts showing and the other just barely in. Re-check the needle bearings and insert the capless end of the cross into the opposite yolk hole, then put the other end fully into the partially inserted cap. While holding the joint- tap the other cap into contact with the joint, align both ends, and insert 'c' clips on the yolk grooves check for binding. It is basically the same process on all the u-joints except the QT end of the CV- recheck the CV ball needle bearings, put some grease in the ball, insert the spring and half yolk, and then start putting in the u-joint.
After assembly- grease joints and CV ball thoroughly and test for binding again before putting it back on the Jeep. I would recommend greasing the shaft itself after reinstallation.
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