How to change a u-joint

If you wheel your Jeep often, chances are that sooner or later you’re going to break a u-joint, either in the front axle or in one of your driveshafts. That or they will eventually simply wear out with old age and need to be replaced anyway. Changing a u-joint can sound like a daunting task at first, but it’s really not that hard and doesn’t take very long to do. Here’s the steps to change a u-joint in your driveshaft. The process is pretty much the same to change an axle shaft u-joint, only you’ll have to do it all twice to get the joint out of both shafts.

To start out with, you’ll need to remove snap rings from the outside of the yoke ears. A pair of needle nose pliers works great for this. Take the rings out of both sides. U-joint caps on axle shafts will have c-clips or full-circle clips on the inside of the ears. Now you’ll need some place to set the yoke on that will allow the bottom u-joint cap to come out the ear of the yoke. I’ve found that a 26-28mm socket works great for this, but you could also set the yoke on a rock or a bumper if you’re out on the trails and don’t have a 28mm socket handy in your toolset yet. You’ll also need a socket to put on the top u-joint cap to help push the joint through the yoke. A 19mm socket works perfectly, but you could use something smaller. With everything in place, start hammering on the top socket — this will push the u-joint sideways in the yoke.

If your u-joint has a zerk fitting in the body, you’ll want to make sure you either remove the zerk first or set it up so that the zerk is pointed up when you’re pushing the u-joint through the yoke. If you don’t do this, you’ll break the zerk off when the u-joint body gets close to the ear of the yoke (yes, this is the voice of experience talking).

Once the u-joint is pressed down as far as it will go, you could be able to grab the bottom cap and pull it out of the yoke. These can sometimes be stubborn if the shaft is old, so you may need a pair of pliers to grab the cap with.

With the one cap removed, you should be able to rotate the u-joint and pull it out of the yoke. If you don’t have enough clearance to get the joint out this way, you may need to use a deep-socket on the cap-less end to press the other cap out the outside of the yoke.

To install the new u-joint, carefully remove one of the caps and insert the new joint into the yoke the same way you pulled the old one out. If the new joint has a zerk fitting in the body, make sure the opening is on the end facing the driveshaft as the photo above right shows. If you install the joint “backwards”, the zerk fitting will be pointing into the axle pinion and you won’t be able to get a grease gun on it (again, the voice of experience talking…). If you had to press the other cap out of the yoke as well, you’ll probalby have to pull the caps off both ends of the u-joint to get it into the yoke, then fit both caps into the ends of the yoke ears.

Center the u-joint in the yoke ears and carefully put the cap back on the other end of the joint. You should be able to slip the cap into the yoke’s ear just a bit, helping to center the u-joint cap on the other end.

Now flip the yoke over and put in the new snap ring — there’s a groove that they fit into on the inside of the yoke ear. Flip the yoke back over and set it up with the sockets (or whatever you used) again like you did in the beginning. Now it’s time to hammer the joint into place. The snap ring (now on the bottom of the yoke) will make sure the u-joint stops in the right place.

When the u-joint bottoms out on the first snap ring, flip it over and put in the other snap ring. Install the zerk fitting and the shaft is ready to go back on the rig. Be sure to grease the joint after you’ve completely reinstalled the driveshaft, that way you won’t push the caps off with the grease (no, that time it wasn’t the voice of experience talking).

That’s it! See, it wasn’t really that bad. The whole process takes about 5 minutes for a driveshaft u-joint, probably about 10 minutes or so for an axle shaft u-joint since you’ve got to do everything twice. New u-joints run anywhere from $10-$30 depending on the quality and name brand, and it’s definitely worth your while to keep one or two on hand as spares during trail runs. I’d also recommend picking up a spare set of yoke straps and bolts (or u-bolts if that’s what your yokes use), as well as an easy-out kit in case once of the strap bolts breaks off inside the yoke.

2 comments

2 Comments so far

  1. drivshaft or just u joints - Jeep-CJ Forums September 7th, 2010 8:53 pm

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  2. steve August 16th, 2011 8:11 am

    thanks- easy to follow!!

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