need to change out the u joints on the rear shaft on my 92 xj. any tricks or precautions i need to know about or is it a normal u joint? thanks in advance.

 

I don't know of any. Be sure to get a 'greasable' u-joint, or at least one that's drilled out. That way you can grease, or, at least remove the two caps daub some grease in it, squeeze with a c-clamp which will force some grease back through the other trunions (if it's 'drilled).

As for installation Pretty standard. The biggest thing a lot of guys overlook is when they finish, the joint is really tight. You need to equalize the pressure so it's not 'squeezed' too much.

 

It was easy enough with a rented ball joint press from O'Reilly. I held the shaft in a vise while using the press. I replaced with greasable Moog branded ones along the drive shaft. They have worked well for over a year now. This is on a 1992 XJ Laredo.

 

Personally I avoid greasable joints because they are weaker than solid u joints. I've not had an issue breaking a u joint in the driveshaft, but I have broken a few axleshaft u joints.

 

Actually the Spicer instructions specifically say do not add grease (for non greasable U-joints).

 

The original non greaseable Spicer joints lasted for a very long time so I've never seen the need to add the greseable kind when replacing them. Why deal with the extra step and mess of greasing them when it's not necessary. They're a 20 min job to replace with the right tool. The time I save not greasing them is probably far greater than that in the time that even non greaseable ones will last.

 

great info, thanks. just trying to make sure i don't get in the middle of this job and find a SNAFU.

 

For the rear, it is a pretty straight forward job. Chock the rear wheel so that it doesn't move on you once the shaft is out, otherwise lining thing back up when you go to put it back in is made more difficult than it needs to be. Most people recommend putting new u-joint straps/bolts anytime a u-joint is changed. They aren't terribly expensive, so I do get new ones when I buy joints. The rear shaft is made up of two sections, so once you have it out, mark them where the two sections meet so that when you put them back together you retain their original orientation.

Don't forget to lube the slip yoke when you reinstall so that it can slide easily. Something you should do anytime the rear shaft comes out.

 

If you do have difficulty aligning the driveshaft upon re-install, you can put the parking brake on (and chock the wheels just to be safe) and put the Jeep in N and the output shaft will rotate freely. You could also put the transfer case in N and get the same effect. You have to slide the slip yoke side on first anyway, then rotate the shaft as necessary to join the rearmost joint into the axle yoke.

I like to mark the axle yoke as well to reinstall everything exactly as it came out.

 

I highly recommend using a ball joint press locked into a bench vise. I bent the handle on my Dad's 30+ year old vise trying to remove a stubborn u-joint. With the BJ press and a breaker bar the u-joint caps came out and went in -like butter- .

Edit -- The biggest thing on re-install to look out for is the needle bearings staying put while pressing the caps in. Once they are on, the joint should rotate smoothly. Tap the yoke ears lightly with a hammer to settle everything. It will be much tighter than the old joints, but if it's not SMOOTH, then you may have a needle bearing stuck under the end. Many folks like to get an extra u-joint just in case they lose or damage one of the needle bearings. Even if you have no problem, it never hurts to have a spare kicking around. Also it's a lot less frustrating if you don't have to drive to the parts store when you're so close to being done.

I had a shop do u-joints for me last year and the shaft came back with a needle bearing under the cap. Against my gut I put it in and it exploded 500 feet out of my driveway and scared the heck out my 4 year-old that wanted to go on the test drive with me. Sheared the strap bolts clean off... Fortunately it didn't damage anything else on the Jeep, but man was I ticked off.

 

If you carry tools and can do a roadside repair, it will bomb on a Saturday evening. Having a spare prevents this.

 

Agreed! But he asked for the rear driveshaft... I would use non-grease type Spicers for the front too. As for not re-greasing a non-greasable u-joint, you just want to match the kind of grease. Many people just pump whatever grease into them ..different greases have different (and sometimes incompatible) soap carrier compounds. So, try to match. How do ya know? There's some guesswork, but look, feel, smell. I would wait a number of years before initial re-greasing, but ...after a few years, I would add a grease. I've been doing it for 30 years and rarely have to replace rear u-joints, so it definitely extends u-joint life.

I personally prefer hammering u-joints out/in vs a ball-joint press. I've done it both ways. It's personal preference but I feel I can control the alignment better tapping in with a hammer. Sometimes with a u-joint/ball joint press, they can bind. Again, personal preference.

 

Good vid to watch

 

The hardest part whenever I've done u-joints is getting the old rusty b@stards out - this is where having a press is helpful. If you can get the old ones out with nothing but a BFH - hey that's awesome - but I've always had at least 1 cap that (in one case soaking for weeks in PB Blaster) simply wouldn't budge without a press. I suspect it's the ungodly amount of salt they dump onto the roads every time it snows, rains in the winter or snow melts onto the road.

Of course, I'm not wheeling, so the u-joints have always been pretty old and/or original. They do say they are a bit easier the more times they've been changed.

 

I have a press, but usually just use the hammer as well. For getting stuck joints out, I keep an old u-joint body on hand. It is excellent for punching out an old rusty u-joint. It transmits energy from the BFH very well.