76-cj7
Ok, i know im prob going to be called a dumbass but in my rear drive shaft the 2 caps in the yoke on my M20 keep breaking the needles which therefore cause the joint to turn from metal to a black powder. So twisted yoke maybe? But it's brand new.........its go a Tom Woods rear shatf but the 2 in the slip yoke are perfectly fine but just the 2 in the yoke bust needles. If i run the dogshit out of it the joint will fail in about 3-4 days but if im easy on it they last 2+ weeks.....at least thats how long this ones lasted. I've gotten prety good on changing joints out quick but im tired of buying them, so what the hell? Auto Zone u-joints to blame? The spicer that was originally sent with the driveshaft had busted needles too. :(:
jeepsr4ever
Ujoint faliure is mainly caused by a lack of lubrication. If you arent lubing these joints after installing I can see why you have alot of worn out needles. Cheap joints are also a mixed bag. You should buy a good joint and use very heavy sticky grease. Caterpillar had some incredible synthetic grease that was very sticky.
76-cj7
Doing all of the above MC.......its getting so bad that i keep 4 spare joints...U-Joints that is.....with me along with a grease gun and needle at all times. Im using a tacky marine grease but i dont think grease would be the problem thou considering its in all of my u-joint and they are good to go......better knock on some wood 8) But what baffles me the most is the only ones i have a problem with are in the yoke on the diff and no other ones :(: But like i was saying before the spicer ones crapped out also. Im betting on the yoke being tweaked, but thats just me. :-|
hugh
I,ll just quote some stuff about driveshafts from the jeep performance handbook. Before that, is your 5 lifted ? because that usually increases the driveline angle since 5,s already have short rear driveshaft. Anyway, Spicer rates their U joints for 5,000 hours at a 3 degree angle. At 12 degrees that life is cut down to 25 percent or 1,250 hours. 15 degrees is the absolute maximum continuous operating angularity for U joints. Even a mild lift will put most short wheelbase jeeps past 8 degrees.
If you are running a 2 joint shaft the pinion and t-case outputs should be parallel. If they arent you can shim the rear diff or lower your T case. Another solution is to run a CV driveshaft, in this case the pinion must be parellel with the driveshaft.
Also your grease should be extreme pressure rated, EP 2 is ok
76-cj7
I have the Advance Adapters heavy duty rear output shaft along with a Tom Woods 1310 cv style shaft. I had to fab up a new crossmember for my trans so when i made it i built it lower than stock and i also cut and move my spring perches so that the angle on the u-joint at the rear end its pretty much flat.......no angle on the u-joint but the cv takes up for the angle.
hugh
it sounds like you,ve got the angles right, so thays prob not causing the u joints to break. How about when you install them? Are you using the straps on the pinion yoke or have you upgraded to u bolts?
76-cj7
U-bolt on the yoke with new everything. Im still leaning twords a tweaked yoke.....although the damn thing is brand new! :(:
JERSEYJOE
ARE YOU SPRING OVER AXLE? IF SO THIS PUTS A LOT MORE MECHANICAL ADVANTAGE ON THE REAR AND TENDS TO TWIST IT UP ON HARD ACCELERATION. THERE ARE KITS TO CONTROL AXLE WINDUP ON SOA SET-UPS. OR YOU COULD SET THE STATIC PINION ANGLE SLIGHTLY DOWN TO ANTICIPATE THE UPWARD TWIST.
JUST MY 2 CENTS
runnamuck
could be tighting the ubolts around the caps to much. crimping the cap and not letting the neddles move resulting in lack of lube. and marine grease is not rated high enough for a ujoint. red amsoil or the syn. cat grease are best.
76-cj7
I know its not the grease since all the other u-joints are quite well with it in there and its still spring under axle and as far as over tightenting........i tighten them just the same as all the others ive changed.
Goose
Ok maybe I have had it wrong all these years but here goes..you have to have some angle on a u-joint or the needles in the caps do not rotate, If they dont they soon get flat spots and poof dust.. If that joint is close to 0 angle..the pinon side of the joint could be zero..I would throw a set of shims under it and see if a degree or two doesnt help..
The only thing I know for sure about drivelines and thier mystical angles etc..Is just about the time I think I understand it, everything I thought I knew turns out to be wrong and I should have done some absurd ass backwards thing that I was sure was wrong.. :mrgreen:
That yoke being tweaked would be a tough deal..with out pulling it and putting it on a known flat surface it would be tough to tell.
76-cj7
Yea Goose.....you do make a good pointbut im going to swap out the rear for another 20 with 4.56's, superior shafts, disc brake and a detriot :mrgreen: because 3.73's suck and a slightly twisted axle tube :smile: and i have no clue how that whould have happened :-| hahaha........yea right :lo1l:
Goose
hmmm twisted axle tube...yup must have been a manufacturing defect!! :mrgreen: :mrgreen:
76-cj7
And yet another one bites the dust......switched yokes this time and notice that my brand new pinion bearings are toast and my rear is for some odd reason 1qt low?? It dont leak so i have no idea where it all went too.......but i suspect the pinion bearings are the culprit as a u-joint fits perfectly in the odd yoke and moves freely with tightened u-bolts. :(:
Rhinolined360
This might sound retarded but for some reason unknown to me my trans mount was loose, which caused my trans to move around, right, well i think it was the reason why my u joints were going so much, "turning to dust". I red loctited my bolts and haven't broke one since. Those straps to hold the ujoints in place are really bad, i use a one piece strap which have bolts on the back of the yoke and haven't screwed up a joint yet.
76-cj7
Motor and Trans mount are both brand new and good shape yet....i opted for stock replacements to take out some of the vibe you get from poly mounts.
