What Happens When A U-Joint Fails?

U-joint failure is a serious issue. When a u-joint on your vehicle fails, you could be left stranded on the side of the road. U-joint failure happens for a few different reasons:

• The vehicle has high mileage
• The vehicle has been in several accidents that caused misalignment
• The u-joint loses grease
• The operating angle is too steep

Signs Of A Failing U-Joint

There are common signs that a u-joint is about to fail. The bad news is that when you notice the signs of a failing u-joint, it’s already too late. The joint will need replacement. But, replacing the joint asap can prevent other problems.

If you notice shaking or vibration when driving, it could mean that your u-joint is about to fail. When you feel the vehicle vibrating abnormally while driving, check your tires for balance and alignment issues. If there are none, then the issue could be with a faulty u-joint. That means that you should get it checked out right away to prevent any further damage from being done.

Driving with a failing u-joint will cause more strain on other components in the drivetrain system. This can lead to other problems such as:

• Severe drivetrain vibrations at certain speeds
• Leaking pinion or transmission seals
• Damage to the driveshaft

Another major sign that you’ve got a bad u-joint is a variety of strange noises. One of the most common noises is a clunking sound when shifting from forward to reverse.

When a u-joint finally fails, it will make a loud popping sound. It may then literally fall apart. If this happens while you’re driving, you may lose control of your vehicle. You’ll also become stranded on the side of the road because your vehicle will no longer be able to move. A failing u-joint can also cause other problems. To be more specific:

Driveshaft Gets Disconnected

This is the reason why your vehicle stops moving after a u-joint fails. The driveshaft can’t transfer to the axle when the u-joint fails. The driveshaft is usually still connected at one end, but is completely free at the end where the u-joint failed.

Transmission/Transfer Case Output Shaft Seal Failure

When a u-joint is failing, it causes excessive vibration. That can cause the driveshaft’s output shaft to rotate out of round. This leads to failure of the transmission’s rear seal.

If not addressed in a timely fashion, this can cause complete transmission failure. It’s because when the output shaft rotates out of round and the rear seal fails, the transmission fluid leaks out. When the transmission loses enough fluid, it can fail.

The same thing can happen to a transfer case.

Pinion Seal Failure

The excessive vibration from a bad u-joint can cause the pinion seal to fail. When that happens, gear lube can leak out of the differential. This can lead to significant damage to the ring and pinion assembly.

Bearing Failure

The excessive vibration from a bad u-joint can cause the following bearings to fail:

• Pinion bearing
• Transfer case output bearing
• Transmission output bearing

The bottom line? U-joint failure leads to expensive repairs. It also makes driving dangerous and difficult for you and everyone else on the road. This is why you need to address a bad u-joint as soon as you notice the signs of a failing u-joint.