Replacing Universal Joints: A Comprehensive Guide

Universal joints, while often overlooked, are critical components in a vehicle's drivetrain. These joints connect the driveshaft to the transmission and differential, allowing power to be transferred even as the suspension moves. Recognizing the signs of wear and knowing how to replace these joints is essential for maintaining vehicle safety and performance. This article provides a comprehensive guide to universal joint replacement, drawing upon the experiences of mechanics and the insights of automotive specialists.

Understanding Universal Joints

Replacing universal joints refers to changing the couplings at either end of the drive shaft, which are an integral component of the suspension system of a vehicle. Vehicle suspension systems are made up of many different parts. Some parts may be going bad, but the entire system will not go bad at one time. It will depend on what's gone bad. Universal joints are a no-glory item. You can't chrome 'em, and they don't make you go faster. However, worn U-joints are a safety hazard and should be replaced at the first sign of a "clunk" in the driveline.

Preliminary Steps: Evaluation and Preparation

The first thing you'll need to do is evaluate the drive shaft you are working on. You should make sure that the rest of the drive shaft is in good condition and that replacing the joints will be enough to get that old drive shaft back in good working order. Things to look for are loose or seized splines, dented or rusty tubes, damaged or worn yokes.

Next, gather your tools. A hammer, preferably a ball peen but a claw hammer will work. Start by cleaning any loose dirt from the drive shaft. A flat head screwdriver works well as a scraper and this is where a wire brush can come in handy. Then clean your work area. You don't want dirt getting into the moving parts of the u joint.

Removing Old U-Joints: A Step-by-Step Guide

Before starting, mark components so they can be reassembled in the same position relative to each other.

Remove Snap Rings: To remove the joints you will first remove the snap rings. If you have external snap rings you will remove them using your needle nose plyers. If you have internal c-clip style snap rings you will remove them by prying them out with your flat head screwdriver.
Remove the Joint: Once the snap rings are removed there a couple different methods to remove the joint. Again, a special u joint removal tool is not required.
- One method to remove the joints is to hit the drive shaft with a hammer while applying slight pressure to the joint.
- Another method is to use the two sockets and hammer. One socket is used as a punch to push the joint through the yoke while the other is used to catch the protruding bearing cap on the other side.

I've made reference to this method for removing u-joints on here many times over the years since I originally read Big_Mark's post 14 years ago. Here's a non-Jeep video I found that shows how to do it. I have been able to remove every joint/cap in minutes, even some where other folks had failed with pressing them out using the sockets/vice "press" method and were ready to give up. The key part starts at 1:51, where he shows which part of the shaft to hit while resting the ears of the other side of the shaft or the ends of the u-joint cross on the vice. You're hitting down on the shaft/ear (start really easy--I think he hits it too hard to start) to pop out the top cap. -You can use rocks/wood/etc to support the ears on other side of the shaft or u-joint cross (be careful and sensible), so this is great for trail repairs. -IT OFTEN DOESN'T TAKE MUCH FORCE - START EASY, there's no reason to beat the hell out of the shaft if it's not needed, a bigger hammer and less force is ideal IMO. The impact load makes all the difference in this method over pressing them out slowly, so use that to your advantage and only use the force needed. Once the cap moves even a fraction, it usually pops out from there very easily. -If you have to reuse the u-joint for some reason, this may not be the way to go for the second set of caps because you have to rest the u-joint cross on the vise/blocks (2:03 in the video). If the caps pop out easily, you won't do much visible damage to the bearing surfaces of the cross, but I'd consider it an emergency-only way to go. I'd probably try supporting the shaft on something and then putting a socket on the top cap to hit to drive out the bottom cap. -Watch the needle bearings carefully if you have to reuse the joint--if there's not much lube in the cross, they could scatter when the cap pops up or when you remove the cap from the shaft ear.

Inspecting and Preparing for Installation

Once all the joints are out you should further inspect all the other parts and make sure nothing else is damaged or worn. If you are working on a double cardan, aka CV, shaft pay extra close attention to the center ball and the pin that the center ball rides on. The center ball should pivot freely but should not wiggle up and down or side to side. The centering pin should be smooth and cylindrical and should not be tapered, have grooves in it, or have any visible wear. If the center ball is bad (and it probably is) you should replace the socket yoke or socket flange. If the pin is bad, you will need a qualified drive shaft shop to replace the weld yoke. This is the point at which it really starts to make more sense to just get a brand new drive shaft.

Thoroughly clean and inspect all mating surfaces of the yoke for any burrs on the inside of the yoke caused by the removal of the old u-joint, especially the snap ring grooves. Remove, lubricate and reinstall the bearing caps of the u-joint (see photos 1 & 2). The recommended grease for u-joints is NLGI #2 GC-LB lithium complex EP grease, preferably a synthetic. If the recommended grease is not available, make sure to use grease that is compatible with lithium grease.

Installing New U-Joints: A Detailed Process

Now it is time for the u joint replacement. To install the new joints you will put the joint in the yoke and push it through one side so that the end of the joint (the trunnion) protrudes out the side. Now put one of the bearing caps onto this trunnion. Use your hammer to tap the cap down into the yoke until flush. Then use the smaller socket to drive the cap below flush. Install the first snap ring then turn it around and repeat these steps on the other side. There you have it.

-Once the new joint is installed, you can use this method LIGHTLY to "seat" the caps back in the ears. (He sort of does this at 13:06, but you can see his tapping doesn't really free the u-joint up enough.) When all clips are in place, you can tap the shafts to push the caps back into the ears so that the cross isn't bound up at all to allow the joint to move as smoothly as possible. Sometimes you can manage to get the clips in but the cap is pushed against the end of the cross tightly enough to cause interference, so the joint won't feel "smooth" (as you can see in the video around 13:06.) Putting all the ears of the finished shaft back in the vice with a couple VERY, VERY LIGHT taps on all ears will push the caps back and free it up. Hope this helps folks.

Additional Considerations and Potential Complications

Driveshaft Balancing

When you're done, take the driveshaft to a professional shop such as Cannon Engineering to have it balanced. The driveshaft spins faster than the crankshaft in an overdrive transmission, so it's important that it's balanced!

TR6 Axle U-Joints

But I tell you what, there's something about removing and installing U-joints on every TR6 axle I've ever seen or participated in was a lot harder than anything I've seen on YouTube…John Twist included.

CV Joint Conversion

While on the topic (sorta) I'm thinking about installing the CV joint alternative to OE and U joints. half shaft upgrade. nothing being perfect,… I would wonder what you do in case of CVJ failure. then each rear wheel hub… it aint pleasant… or the now seeming lifetime lubed non zerks…

Driveshaft Removal

Well you can't get the driveshaft out without dropping the rear end. Ralph - are you thinking drive shaft and I'm thinking the axle shaft? No I was stating if you were going to do the driveshaft you would need to drop the diff.

Universal Joints on F-150 Extended Cab Truck

Can the 2 rear joints be changed without having to remove or disturb the carrier bearing on a 92 f-150 extended cab truck? The front and rear section of the drive shaft are spliced together at the carrier bearing so yes, you can remove just the rear section. While the driveshaft is dismounted, examine the yoke seal for wear.

Lakewood Performance Joints

Lakewood offers replacement performance joints with high nickel content crosses and no zerk fittings. Zerks are great for greasing, but they weaken the joint. Unbolt the driveshaft from the car and remove the C-clips that hold the U-joints together. External clips can be removed with needle-nose pliers; internal clips can be removed with a screwdriver. Next, remove the caps by pressing the cross through the yoke. A vice will also work, but be careful not to dent the shaft or warp the yoke. The bottom of the yoke must be supported with a large-diameter socket so there is room for the cap to be pressed out. Once all the joints are removed, clean up the driveshaft and yoke. The input shaft on the yoke should be dressed for a good seal to the transmission or replaced if worn severely. Now you're ready to install new joints. Install one cap and a C-clip to either the shaft or the yoke. Fit the cross into position, then press the cap onto the opposite side being careful not to bend any needle bearings. If your joints have zerk fittings, install them so the zerk is under compression when the car is moving forward. C-clips should be installed on the caps that bolt to the differential because they center the joint. The yoke on the left uses an inside clip because it has no locating bosses. The yoke with the locating bosses is for joints with outside clips.

Time Investment

First time----eight hours. After that, six to four hours. Bless those who can do it in two hours. We usually find other things to do when taking apart these areas. Replacing the u joints is fairly quick, getting the half shafts out takes most of the time. It took me about 30 minutes total ….. because I took the axle shafts to a local shop that does great work. But it will still probably take that long.

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