U joints going out faster than my diesel!

[Beave32]

For the life of me I can't keep a u-joint in my truck for more than a month. I hear like a sharp popping noise when I let the clutch out and that lasts for about a week then it gets really bad. Any ideas what might be causing it to lose them? Or if someone thinks it may be something else...I also may have considered the problem to be a loose pinion nut but I tightened that down. Any suggestions are much appreciated


1988 F-350 custom 7.3...Dana 80 rear end

 

[icanfixall]

What grease are you using on the new joints... What maker is the new joints.... Which joint is failing....

 

[Beave32]

The new ones came pre greased...I shot a little more in there and that was a synthetic hi-temp grease. I bought them from shucks and I believe they are "precision" joints. I'm not sure if it is one or both. Another thing I forgot to mention is that I think my tranny mount might be loose somewhere because whenever I let the clutch out the shifter gets thrown around an unusual ammount. I was thinking this could be throwing my driveshaft out of balance and cause the joints to fail?

 

[sootman73]

do you "tune" the u-joints after you install them? you cant just put them in and be done. you have to "adjust" the yokes so that there is the correct amount or resistance in each direction yet not too much to produce a bind...

 

[Beave32]

I don't "tune" them...Never heard of anyone doing more than just slappin em in...DO explain please!

 

[Diesel JD]

I was told one should have the driveshaft rebalanced anytime you change anything in it, including U-joints. I also hear that the non-greaseable u-joints tend to last longer, that doesn't make sense but I have heard it.

 

[sootman73]

Its kinda hard to explain through words but i'll give it a try.

when you get a new joint all the way in move it in both directions. it shouldn't be loose but it should be easy to move. It should also feel the same in all directions. If it doesn't you have to play with hitting the yoke with a hammer in the spot shown below. And you have to adjust all four sides. You will notice a difference as you play with it and its pretty much a time job until you feel that there is the right preload on the bearings in side to side and up and down directions.

Hope that helps a bit.

 

[Agnem]

Maybe I misunderstand what your saying, but if your implying that there is movement in a new U-joint in ANY direction, you've got a serious mismatch of parts! A new U-joint should have no perceptable play in any direction at all. If it does, then you don't have the right U-joint.

 

[HammerDown]

Mel...
I don't think sootman is referring to in-out "play" in the joint but more of a binding.
I too give a little tap-tap to the center cross/body (if) after pressing in a cup feel a slight binding or resistance when moving it by hand.
Of course before installing any u-joint one must make sure where the cup seats is clear of any small debris > this in itself will force the cup into the center body and cause such a bind.

 

[Knuckledragger]

U joints don't like shock of any sort, nor do they like changed alignment while driving or excessive static alignment. If you have a broken trans mount or loose differential bushings, you could be fixing the broken parts but not the cause of the breakage. If your truck is raised a lot, check for binding on suspension travel. The trunnions are way stronger than the U joint.

 

[franklin2]

The binding is just from the cross rubbing against one of the caps after installation. I don't see that causing the joint to fail prematurely.

I am wondering how much lift this truck has, and how much of a bind the u-joint is in because of it.

 

[lotzagoodstuff]

It very difficult to troubleshoot when you have multiple problems/variables. Fix your tranny mount, then see how long your u-joints last.

 

[White Trash]

How did the first u joint go out? Did it wear out or did it go out busted into pieces? Also which joint is it that's going out?

 

[Rot Box]

Make sure your angles are correct. The yoke on the t-case and the yoke on the pinion should match angles like this | | with 0 degrees difference from one another--I'd use an angle finder to check this. You can get by with a little difference as many people do but if you have to set it you might as well get it perfect or close to it. This link is helpful: http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml#Measurements Depending on gearing and tire size etc. you might not notice any vibrations but the angle could still be off enough to wear U-joints. If your truck isn't lifted at all I wouldn't worry about any of this

To adjust the angle you need to add shims (use steel not aluminum) on top of the spring perch but if your angle is set right and the driveshaft is on too steep of an angle you may need a CV joint in your drive shaft. With a CV you can point your pinion up so it points at the t-case and eliminate the bind.

Remember without a CV you want the yokes to be parallel || with a CV you want the pinion pointed up so the pinion gear shaft is directly in line with the driveshaft if that makes sense.

Also what U-joints are you using? I would stick to the non grease able Spicer brand

 

[White Trash]

Make sure your angles are correct. The yoke on the t-case and the yoke on the pinion should match angles like this | | with 0 degrees difference from one another--I'd use an angle finder to check this.

Close but a bit off... the pinion should be pointed about 2* lower than the t case output allowing for axle wrap to make the angles closer to exact. This holds true when using a CV as well buy you need to have the axle pointed 2* lower than being directly at the output on the case.