U-joint questions

How can you tell when a u-joint goes bad? I have a driveline vibration, its a u-joint or the carier bearing. How can I tell which u joint is bad?

 

Rotate the driveshaft by hand while the truck is on the ground and parking brake engaged. A worn U-joint would have slop.

 

Thanks will try!

 

I just replaced my ujoint. for 15$!!! rockautoparts.com is the way to go. As described earlier, check for play. Inspect the rubber looking boots on the inner part of the housing. If you conclude that its the Ujoint.. then watch the video link below. Its a three part video! GOOD LUCK!

http://www.youtube.com/watch?v=6tJWEVGqP6s

 

Thanks for the vid!
Ok so went under the truck to check for slop. Ebrake on truck not in gear.
Did not see anything that looked like serious slop. I will go put the truck in gear and try again. Also will check my trasfer case level.

 

Sometimes you will not feel slop in the ujoint. I have had cases in vehicles where the joint has started to freeze up and you can't feel any slop. If you have the means, take the shaft out of the truck and move each ujoint through it's full motion and see if there is any roughness. Also check to make sure you have not lost a balancing weight on the shaft and that there are no dents to the shaft.

 

Thanks!

 

So while under the truck, I inspected the trasfur case and rear diff, both full and fluid looks good.
While there I figured I would grease everything, I got grease in everything accept the double caragin(sp) joint. They must be clogged the zerks would not take any grease. So need to figure that out.