How to Replace U-Joints (2024)

Introduction to U Joints

U joints allow the drive shaft to pivot on both the vertical and horizontal axes, providing flexible and uninterrupted power transfer from the transmission to the drive wheels. They are often found in rear-wheel-drive, all-wheel-drive, and four-wheel-drive vehicles.

The T-shaped part has two opposing ‘arms’ secured to the driveshaft and two that secure to the adjoining part. Designs can vary, but the vast majority of U joints have caps with lubricated needle bearings that are secured at the differential, at a yoke that slides onto the transmission output shaft, or mid-shaft to provide the pivot point.

Regular inspection and maintenance can prevent driveline vibration, noise, and the eventual failure of these critical components. A shot of grease at least once per year is a good plan, and checking for excessive wear or failures should be part of every service interval.

If it fails, there will be progressive symptoms like a clicking or knocking noise with drive shaft rotation, clunking when you shift into gear or accelerate and brake, and if it fails completely, it can separate in catastrophic fashion and cause you to lose control while you drive.

The first step in any vehicle repair or maintenance project is ensuring that you have all the necessary tools and equipment. The tools required for a U joint replacement are comparatively simple, but selecting the right ones can make the process significantly smoother.

You’ll need:

• Jack and jack stands
• Socket set
• Wrenches
• Snap ring pliers
• Pry Bar
• Hammer
• Grease gun

Also, you should wear protective equipment whenever working on parts like the driveshaft and U joints. Wear safety glasses, gloves, and avoid loose-fitting clothing that could get caught in moving parts.

Locating and Accessing U Joints

Depending on your vehicle’s make and model, U joints can be found at various points along the drive shaft. You may need to remove underbody covers, cross members, or parts of the exhaust system to access the U joint. If you don’t create enough access, it will almost certainly be a more difficult process than it needs to be.

Step-by-Step U Joint Replacement

Replacing U joints can seem daunting, especially if you’re new to vehicle maintenance. By breaking down the process into manageable steps, you’ll be able to tackle this task with confidence.

Removing Old U Joints and Preparing for Installation

Step 1: Mark the Drive Shaft

Before disassembly, mark the relationship between the drive shaft and the flanges to ensure proper alignment upon reinstallation. Chalk or touch-up paint work well for this. Then, remove the drive shaft. Often, it’s a matter of unbolting it from the differential and the hanger bearing, then sliding it from the transmission yoke.

Step 2: Remove Snap Rings

Use snap ring pliers or a large flat screwdriver to remove the retention rings from the U joint bearing caps, depending on the design.

Step 3: Press Out the U Joint

A press may be necessary to apply even pressure when removing the old U joint. If you don’t have a press, carefully use a hammer and an appropriately sized socket to tap the U joint out from the drive shaft.

Installing New U joints

Step 1: Fit the New U Joint

Ensure the U joint is the correct size for your drive shaft and fits snugly into place. Some designs may require removing the end caps, fitting the joint, then installing the end caps in place. Be sure not to lose bearings or get dirt into the caps, and avoid forcing caps into place as it can damage the bearings.

Step 2: Secure Bearing Caps

After fitting the new U joint, use new retention rings or snap rings to secure the bearing caps. Some designs may require that caps are tapped into place with a hammer or pressed in.

Step 3: Align the Drive Shaft

Line up the marks you made earlier to maintain proper balance and minimize driveline vibration, then fasten the drive shaft back into place.

Applying the correct amount and type of grease is essential for the smooth operation and durability of your U joint. Over-greasing can lead to overheating and failure while under-greasing can cause premature wear and failure. Use a grease gun to inject the proper amount of grease into each bearing cap.

Troubleshooting and Common Issues

Even with careful preparation and following the step-by-step guide, you may encounter challenges when replacing your U joints. Knowing how to troubleshoot these issues will help ensure the success of your project.

• If your old U joint is stuck or difficult to remove, try applying penetrating oil and letting it sit before retrying.
• Sometimes, snap or retention rings are damaged during removal. Be sure to replace them with new ones to keep your bearing caps secure.
• If you experience driveline vibrations after replacement, it’s possible that the drive shaft is out of alignment. Double-check your marks and realign as needed.

Precision is key, so don’t rush through any step. Before putting everything back together, double-check the condition of all parts, and torque all of the fasteners to spec. After the replacement, take your vehicle for a short test drive. Listen for any unusual noises or vibrations, which may indicate a problem with the U joint installation or alignment.

Looking for a new U joint for your vehicle? You’ll find the right fitment at AutoZone from trusted brands like Duralast. And if you’re not sure you’ve got the right part selected, we’ve got you covered with trustworthy advice. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

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