What are the signs of a bad U-joint or driveshaft?

Summary:

Jaden identifies vibration as the most common indicator of a bad U-joint or driveshaft. He then describes a second symptom specific to a failing U-joint, which is a squeaking noise. He explains the mechanism behind that squeak by describing how a U-joint is built: the joint is shaped like a cross, with caps on each end that contain needle bearings. When those needle bearings fail and run dry, the joint squeaks as the vehicle is driven. His answer gives customers two distinct things to notice, a vibration felt through the vehicle and an audible squeak at low speed, and connects the squeak directly to loss of lubrication in the needle bearings inside the caps, which explains why the noise develops gradually rather than appearing all at once.

Answer:

Bad U-joint or driveshaft. So a lot of times if you got a bad U-joint or driveshaft, you'll have a vibration. If you have a failing U-joint in particular, there's a lot of times that they will make a squeak noise. The way that U-joints work is they look like a cross, and then there's caps on each end with needle bearings inside of them, and the needle bearings fail and they get dry, and then it'll cause a squeak as you're driving. So those are the two things to pay attention to. The vibration is usually what people notice first because you feel it through the vehicle, and the squeak is what you hear at lower speeds. Both of them come back to those needle bearings inside the caps. Once they've dried out and started to fail, the joint isn't moving the way it's supposed to anymore, and that's what you're feeling and hearing.