Bad U-joint symptoms include a clunk when shifting into drive or reverse, a squeak or chirp at low speed that rises with road speed, vibration that grows with speed, and a ringing or clunking when you get on and off the throttle. U-joints connect the driveshaft to the transmission, transfer case and axles on rear-wheel-drive and four-wheel-drive trucks and cars. A U-joint that fails completely can drop the driveshaft, which is dangerous, so do not ignore the warning signs.
U-joint symptoms
| Symptom | What it suggests |
|---|---|
| Squeak or chirp at low speed | Dry, worn needle bearings |
| Clunk when shifting into gear | Play in the joint; see car jerks when shifting |
| Vibration that increases with speed | Worn joint or driveshaft imbalance; see car vibrates at high speed |
| Rust-colored dust around the bearing caps | The bearing has run dry and is wearing |
| Transmission fluid leak at the rear seal | Driveshaft wobble from a worn joint can damage the seal |
U-joint diagnosis
- Park on level ground, chock the wheels and put the transmission in neutral only if safe to do so with the parking brake applied.
- Grab the driveshaft near each joint and twist and lift it; any clunk or visible movement in the joint means it is worn.
- Look for rust dust, missing grease and damaged caps.
- Check that the driveshaft has no missing balance weights.
U-joint symptoms on pickups
On trucks such as the F-150 and Tacoma, U-joints are often the first driveline part to wear, especially with towing, off-road use, lifts and water crossings. A clunk when shifting from park into drive is a common complaint; check the U-joints before suspecting the transmission.
Is it safe to drive?
A squeaky U-joint can go a while, but a joint with visible play can break. When a rear U-joint fails at speed, the driveshaft can drop and dig into the road or damage the underside of the truck. If you hear a new clunk or feel a growing vibration, have the joints checked before a long trip or towing.
Greaseable vs sealed U-joints
Many factory U-joints are sealed for life. Replacement joints often have a grease fitting; grease them at oil changes, until fresh grease appears at all four caps.
Replacing U-joints
U-joints are pressed in and held with clips or straps. Mark the driveshaft’s position before removal so it goes back in phase, and replace all worn joints at once.
Lifted trucks
Lifts increase driveshaft angles, which wears U-joints faster and can cause vibration on acceleration; correct the angles when installing a lift.
Related
See differential noise, transfer case problems, transmission noise and bad CV axle symptoms for front-drive vehicles.
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