Do It Yourself U-joint Replacement
By: John Nutter - 10/2001
Painless Axle Shaft U-Joint Changing
Changing front axle shaft U-joints, what could be simpler? If you are asking that question you have obviously never dealt with severely rusted joints from an older street driven Jeep that's never been in 4wd and has an open knuckle front end. Many a Jeeper has discovered that newly acquired Jeep that has 'never been off-road' equals rusted front axle shaft U-joints that are thoroughly seized into the shafts as well.
The question of the easiest way to change those U-joints at home is a common one for the new owner of a vintage CJ5 or CJ7, so I'll give my explanation of the best way that I've see that doesn't involve expensive tools. I saw this done by Ken Niles of Ken's 4x4 and tried it myself after seeing how easy it was. I've tried a variety of other methods in the past including the 'hammer and sockets' method and using a 20-ton press, but over the last two years I'm convinced that the method I'm about to describe is the best for a home shop.
Removing the Clips
The basic idea here is to remove one rusted bearing cap at a time, minimizing the force needed and the potential for damaging parts. Step one is to remove the 4 C-clips that hold the caps in place. These are located on the inside of the ears and are often rusted in place. I've found that hitting the cap with a hammer will often loosen up the clips, allowing removal with a screwdriver. Photo 2 shows a clip half way off.
|Photo 1: The red arrow points to the clip that holds the U-joint cap in place. There is one on each cap.||Photo 2: The clip is almost off in this photo. It was tapped out using a hammer and a flat blade screw driver.|
Removing the Bearing Caps
Once the clips are removed you can start getting the caps out of the shafts. Open the jaws of your vice just wide enough to support two of the ears as shown in Photo 3. Pound on the thick part of the shaft, just to the inside of the cap to begin backing the cap out. Photo 4 shows where to hit. The cap will back out of the shaft as shown in Photo 5.
|Photo 3: The shaft positioned on the vice, ready for removal of the first cap. The lower part of the axle shaft should just slip between the vice jaws.||Photo 4: Here is where you hit the shaft. This part of the axle shaft is strong and should be able to take the blow. Don't hit the U-joint cap.|
Once the clips are removed you can start getting the caps out of the shafts. Open the jaws of your vice just wide enough to support two of the ears as shown in Photo 3. Pound on the thick part of the shaft, just to the inside of the cap to begin backing the cap out. Photo 4 shows where to hit. The cap will back out of the shaft as shown in Photo 5. When the cap is as far out as possible, grab it with a pliers and pull it the rest of the way off. Flip over the shaft and repeat to remove the opposite cap. Remove the U-joint cross from the shaft when both caps are out and set the shaft aside. Move the vice jaws in to support the arms of the cross and repeat the procedure to remove the other two caps.
|Photo 5: The first cap is almost out in this photo.||Photo 6: The first cap is out.|
|Photo 7: Close the vice enough to set the bare ears of the cross on it to remove the caps from the second shaft.||Photo 8: Avoid bending the sheetmetal support for the floppy seal. Spindle bearing kits sometimes include this piece of sheetmetal if you do happen to bend it.|
Reassembling the U-joint and Axles
To install the new U-joint start by setting a cap on a solid flat surface. Follow the U-joint manufacturers lubrication recommendations, but don't add so much grease that the cap hydraulically locks before it is all the way in place. Put the cross into the shaft and set the shaft on the cap. Seat the cross in the cap to prevent the needle bearings from falling over and pound on the same part of the shaft as before to seat the cap. Flip the shaft over and support the cross while tapping the cap in far enough to allow the clip to be inserted. Next set another cap on the solid work surface and repeat. This time try to balance the cross between the two caps to prevent the needles from falling over. I usually end up holding the cross and outer stub shaft in one hand while I pound on the axle shaft with the other. Repeat the procedure for the other shaft and install the clips.
|Photo 9: Start re-assembley by setting a cap from the new U-joint on a solid work surface.||Photo 10: Insert the cross into the axle shaft and then set the shaft over the cap. Push the cross down into the cap to hold the needle bearings in place. Tap on the same part of the shaft as before to install the cap||Photo 11: Installing the third cap.|
If the U-joint feels tight try tapping on the shafts in the same spot as before, this often loosens the joint.