My F250 started vibrating a few weeks ago. Anything above 50 gets a vibration that rattles the door panels and feels like a driveline thing. Suspect u-joint. Heard a cracking sound only once with a shift into reverse. Got underneath and tried to twist the driveshaft around while in neutral. Can't seem to isolate if it is a u-joint? What is a good method for checking out u-joints? Besides replacing them.

 

Check the shaft for movement like you did but you want the trans in gear. Push up and down on the shaft. It will be pretty obvious. I didn't the noise so I can't call that but don't forget that tires can cause vibrations and balancing them won't change anything because there is no weight on them on a balancer. Generally tires that do this or on trucks that haul alot of weight.

 

To me your U-Joint problem is not a loose joint but one that is binding up. The only way I have ever been able to check it was to pull one of drive shaft loose feel the joint then move the drive shaft around to see if that joint is binding. Do the same if it is a 4x4 on front. If you have hubs that driveline is not working.

 

I agree... had the same problem a year ago. The rear U joint had siezed up and was binding. Replaced both U joints to be safe... new U joints have a grease fitting to prevent the problem from happening.

 

Yep. It's a U-joint, and its getting worse. Now it clunks when going forward to reverse. The front one is now so loose I can wiggle it. Better take the cavalier to work at risk of doing an endo with the truck. Thanks for the tips.

 

BUT, make sure you grease them. If not there is no point in having the grease fittings. I grease all the u-joints and front end parts every oil change. Works well.

-Matt