A U-joint, or universal joint, is a component of the driveshaft that sends power from the transmission to the differential, and without it, your car will not be able to drive. When your car’s U-joint starts to fail, there will be signs warning you of its impending demise. Looking for these warning symptoms and knowing there is a problem in advance may save you from having your vehicle towed when the U-joint completely fails.
CLUNKING AND CLANGING
Your car’s U-joint may eventually wear at connecting points to the driveshaft. When that happens and you shift your transmission from one position, such as reverse, into “drive,” you will often hear a loud clanking or clunking.
When your driveshaft goes out of balance, often caused by a defective universal joint, you will usually notice a vibration that increases in intensity as your car’s speed increases. Sometimes it can be easy to confuse this vibration with a wheel balance issue, but there are telltale differences to look for. A vibration created by wheel imbalance will have a consistent, steady vibration when the car is in motion, but a U-joint failure will cause vibration when both accelerating and decelerating. Additionally, when your car is not moving, the vibration will stop, even if you gun the engine.
GRINDING OR CHIRPING
In the course of time, the grease inside a universal joint can dry out and cause the roller bearings to wear small indentations into the section known as the cross. This sound comes from the bearings when being forced over these indentations.
At some point, a vehicle’s U-joint will break apart, separating the driveshaft from the transmission. When this break occurs you will usually hear a loud noise, like metal striking against metal. Should the U-joint go bad completely, your car will fail to respond to any power it gets from the transmission and will be unable to move forward or backward. This can be a very dangerous situation, so be observant when you observe your car making strange sounds and avoid letting the problem get this far.
NOTICEABLE JOINT MOVEMENT
If you have a mechanic’s rack and have seen any of the previous symptoms, you can inspect your universal joint and know for certain whether it require replacement.
Raise the car and with the car in gear and the emergency brake engaged, find the drive shaft. Try to turn it and if there is any movement from the U-joint, it should be changed as soon as possible.