SO, what kills u-joints?

[shadango]

I know vibration and abuse can kill u joints.

I have had some new vibrations and new noises coming from out back lately. Thought the noise was exhaust. I had grabbed the shaft a couple times before and the ujoints seemed ok. 

Well, found out today that the Napa "super heavy duty" u joint (shaft to rear end) was bad...the caps on the rear end yoke had lost all the pins/bearings.

Got the new joint at Autozone (gold) and its a permanantly lubed one....lifetime warranty.  The old one was one you needed to lube.

Thing is I got only about 8-9k out of it....so SOMETHING killed it.  Could have been all the vibes I had when I had the old convertor in..or the first two rebuilds of the tranny that were HARD shifting.......or maybe I didnt lube it enough...or maybe my add-a-leafs in the back has the rear at a bad angle...or maybe its the occasional hard launch/burnouts I do...LOL....or maybe it was a poor install of the last ujoint by NAPA (they pressed it in for me last time...I did it this time myself).

I know there are tons of things that can kill u joints....I am leaning toward either the add-a-leafs or vibration.

I do plan on having my shaft looked at for balance when I get the new chunk over the winter (at least that is my plan)....

What is you guys' experience as far as longevity?  Hell, all the rear drive vehicles i have had, I dont recall EVER having bad ujoint. 

Also, at the front yoke where the slip joint occurs.....is there usually a wee bit of slop?

[GoodysGotaCuda]

Whats your pinion angle look like? Not sure on the spec, but I'd make sure that wasn't anything crazy.

[shadango]

Well, looking at it from a standpoint of 4x4 trucks that I have had and that I see, its not anywhere near crazy.   

The add-a-leafs take the rear up about an inch or two (as measured at the back bumper) higher than super stocks....I compred my measurement to that of a guy with SS springs.

I am new to measuring that angle, so will have to look into seeing how its measured I guess and do so.

[Chryco Psycho]

you can buy an angle finder for $10 or so & measure the angle of the diff & driveshaft , the diff should be 5-7* nose down from the driveshaft . L:ack of lube will kill it fast , vibration wil not help either

[72cudamaan]

Did the bearings come out in powder form? Most failures I see are lack of lube.

[BIGSHCLUNK]

Everything here makes sense but when I read your post.... the only thing you did not mention was pinion angle.   Lack of lube would be top of my list tho.....

[Bullitt-]

Also, at the front yoke where the slip joint occurs.....is there usually a wee bit of slop?

I'd call it pretty tight

[shadango]

Did the bearings come out in powder form? Most failures I see are lack of lube.

Pretty much, yeah.....the lube hole in the joint seems like its caked with a dry solid instead of grease....I did lube them when I installed but truthfully didnt touch them since....about 9k miles.   But the front u joint and the shaft half of the old joint seem fine.

[burdar]

Improper installation could have led to the failer.  U-joists should be installed with a press.  My old boss installed them with a hammer and a vise.  Beating on the driveshaft can tweak it enough to put extra pressure on the joint when it moves.  On more than one occation, a joint would move hard once my boss had the joint installed.  A few wacks with a hammer and it would free up.  That doesn't mean it was done right though. 

[shadango]

Well, I think I installed this one right.......one thing I dont get is how it stays lubed, since its sealed.  It came with lube in in but doesnt that lube dry up with heat?

[nqkjw]

one thing I dont get is how it stays lubed, since its sealed.  It came with lube in in but doesnt that lube dry up with heat?

Yep.It sure does.
Then it fails and you have to replace it.
Give me greaseable Ujoints any day.

[72cudamaan]

I almost always installed u-joints with a hammer for 23 yrs. at our shop and don't recall any failures because of that. The grease doesn't dry up with heat. It is slowly lost by centrifugal force around the seals. That's why you have to grease them. Also when you do lube them, make sure that grease comes out of all four seals, otherwise you end up with a dry cup.

[brads70]

Well, I think I installed this one right.......one thing I dont get is how it stays lubed, since its sealed.  It came with lube in in but doesnt that lube dry up with heat?

I had an 81 Malibu with a 383 stroker ( Chev) That car taught me to just use the good hardened u-joints. With the stock replacement u joints I would get about 3 good launches ( just fooling around on the street) and it would twist the u joint and it would cause a vibration. When I took it apart the u joint was twisted and the needle bearings were twisted too. ( brand new u joints) When I went to hardened non greasable u-joints I never had a problem. Ya I guess they don't last as long but "if ya wanna play , ya gotta pay" Let's face it with our cars they get lots of "lovin" and we don't drive them 60-100,000 miles without ripping them apart and improving/upgrading them anyhow, so what's a pair of u-joints every 3-5 years? I don't know about everyone else but my "baby"/Challenger get better maintenance than my regular drivers! I enjoy/love working on the Challenger....the others...because I have to?
My BB Buick Regal has a brand new drive shaft and hardened u-joints and so far no issues either!
So naturally with a Mopar I went to the hardened u joints right off the bat!
I figure stock u-joints are for "stock" engines?

[shadango]

I almost always installed u-joints with a hammer for 23 yrs. at our shop and don't recall any failures because of that. The grease doesn't dry up with heat. It is slowly lost by centrifugal force around the seals. That's why you have to grease them. Also when you do lube them, make sure that grease comes out of all four seals, otherwise you end up with a dry cup.

Well, I talked to the guy at autozone about that...an old grizzled guy who just had that "something" about hi, to let you know he knows stuff.  He said the seals on these sealed units are specially designed to not loose the grease when in action.....so I dont know.

That, and my Durango has sealed ujoints.....72k miles so far and no issues.  So there must be something to them I guess. 

How often should greasable u joints be greased?

[shadango]

I had an 81 Malibu with a 383 stroker ( Chev) That car taught me to just use the good hardened u-joints. With the stock replacement u joints I would get about 3 good launches ( just fooling around on the street) and it would twist the u joint and it would cause a vibration. When I took it apart the u joint was twisted and the needle bearings were twisted too. ( brand new u joints) When I went to hardened non greasable u-joints I never had a problem. Ya I guess they don't last as long but "if ya wanna play , ya gotta pay" Let's face it with our cars they get lots of "lovin" and we don't drive them 60-100,000 miles without ripping them apart and improving/upgrading them anyhow, so what's a pair of u-joints every 3-5 years? I don't know about everyone else but my "baby"/Challenger get better maintenance than my regular drivers! I enjoy/love working on the Challenger....the others...because I have to?
My BB Buick Regal has a brand new drive shaft and hardened u-joints and so far no issues either!
So naturally with a Mopar I went to the hardened u joints right off the bat!
I figure stock u-joints are for "stock" engines?

So, how do you know they are "hardened" ?

The first ujoints I bought (one of which is still in the car, tranny end) are "super heavy duty" units from napa.....for 4x4s.