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Author Topic:   Eating up rear u-joints
xhubby
Dirt Freak

Total posts: 376
posted April 18, 2005 04:52 PM  
Our rear u-joints are only lasting about 2 nights. It is always the caps that are on the u-bolt sides. We ran the same drive shaft (new), u-joint, and rear yoke for the last part of last season with no problems. We checked it before the 1st night this year, & it was shot. Put a new one in, & it was shot after the 2nd night. We have new u-bolts, & are running the best u-joint we can find. Pinion angle is at 7*. Could the rear yoke have gotten tweaked some how?

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted April 18, 2005 05:15 PM  
It could be, also it could be that you are over tightening the u bolts on the driveshaft, you should only need to snug them up

donslink1
Dirt Freak

Total posts: 318
posted April 18, 2005 06:24 PM  
My self I would tighten them, what kind of pull bar are you running, Is it one of those two way afco ones. if so maybe you are getting too much pinion angle when you let off. just a thought.
Or too much lateral movement on rear end, I dont know I would think it would have to be getting too much angle some where or how.

dirtracer14
Dirt Forum Champ
Total posts: 1261
posted April 18, 2005 07:46 PM  
You are tightening to much. Call a driveshaft place they will tell ya you dont have to get them super tight.....not finger lose but nice and tight with a lock washer or a lock nut is fine. My buddy would only get 1 or 2 races out of his... i loaned him a shaft i ran all year on the same joints and he burnt it up first time out.... i asked him how tight he got em.....and he said oh i got em real tight.... i told him to just make it tight enough to when you hold the drive shaft it just pulls out of your hand when tightening.....He hasnt lost one since!!!

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 18, 2005 08:34 PM  
Have to agree with getting them too tight. Use nylock nuts on them and just pull them up snug with a wrench only need like 5# or so of torque. Dont really torque down on them. You only have to keep them snug to the yoke, they cant go anywhere unless the ubolt breaks. When you tighten tthem down you flatten and oblong teh cap and it the rollers inside cant do their job.

RPM08MOD
Dirt Full Roller

Total posts: 30
posted April 18, 2005 10:34 PM  
You didn,t say what rear suspension you running,but I had same problem last year on a 3-link car. Figured it out at the end of season. Make sure your rearend is rotating up enough for the pinion angle you are running,under acelleration your drive shaft should be inline with your pinion if not your u-joint will be in a bind also check your yoke carefully to make sure your caps are sitting in it square. I took pinion angle out and changed yoke and solved problem.

xhubby
Dirt Freak

Total posts: 376
posted April 19, 2005 04:35 AM  
We are running a 2 link with an x-factor pullbar. Getting about 2-1/4" travel on the pullbar. Pinion angle is at 7*. We've been real careful not to over tighten the u-bolts, just snugging them. We have talked to a driveshaft place. We have a place here in town that builds driveshafts, & u-joints.

driver27
Dirt Maniac

Total posts: 194
posted April 19, 2005 06:25 AM  
I have had the same problem on occasion, I usually find that swaping to a different yoke makes a difference on u joint life, as well as how tight you get the u bolts. Ive always wondered if the moroso u joint bolts that cature the u joint are any good. Anyone ever try those with any success?

dluna
Dirt Freak

Total posts: 334
posted April 19, 2005 07:20 AM  
Dumb question I know...but how can you tell when the u-joint has gone bad? In what ways does it change? Is it just hard to swing the cup sides back and forth freely?

THANKS

[This message has been edited by dluna (edited April 19, 2005).]

trasrat89
Dirt Full Roller

Total posts: 46
posted April 19, 2005 08:12 AM  
Yes. Sometimes you can hear them squeek as the driveshaft is turning.Take the driveshaft out, remove the caps & look at the needle bearings & where they ride. You will be able to see if the needle bearings have been hot by the discoloration of the area that they ride on.

ford5
Dirt Forum Champ
Total posts: 711
posted April 19, 2005 04:45 PM  
I had this happen to us one season a couple years ago, and it turned out to be the rear yoke.....replaced it and no more trouble

rrrrick
Dirt Maniac

Total posts: 192
posted April 19, 2005 05:20 PM  
Drive line angle plays an important part in U-joint wear.
Try and keep the angle of the transmission u-joint and the rear end u-joint the same
( has to do with the elliptical motion of the drive shaft angle)
IF you want to get technical you can check out the following sites for more information

http://www.drivetrain.com/driveline_troubleshooting.html
http://www.bgsoflex.com/cgi-bin/dshaft?ang=5.0&rpm=6500
http://encyclopedia.lockergnome.com/s/b/Universal_joint

52mod
Dirt Roller

Total posts: 11
posted April 20, 2005 10:38 AM  
I had this exact problem a year ago. Turned out the pinion yoke was bent. I found it by placing a brand new joint in the yoke and tightened the U bolts down and it bound up instantly. It's easy to check without the driveshaft connected to it.

[This message has been edited by 52mod (edited April 20, 2005).]

NJantz
Dirt Forum Champ
Total posts: 755
posted April 20, 2005 11:28 AM  
I fought this problem for a long time. Sometimes the needles would even burn holes right through the caps. I switched to the moroso girdles, ran a solid pullbar, made sure the caps were just snugged up, changed rearend gears, and still had problems.

I finally changed the driveshaft, trans yoke, and switched to the AFCO ujoint and my problems went away.

good luck.

uforacing51
Dirt Forum Champ
Total posts: 570
posted April 20, 2005 02:08 PM  
This is a good case for one of them suspension cameras!!

xhubby
Dirt Freak

Total posts: 376
posted April 20, 2005 06:01 PM  
Mod52, I never thought about trying that. I got my kid on it right now. Thanks.

xhubby
Dirt Freak

Total posts: 376
posted April 21, 2005 04:16 PM  
Yep, bent pinion yoke. Put the u-joint in without the driveshaft, & it was very tight. Now to find a good yoke. Thanks again 52mod.

T/10
Dirt Full Roller

Total posts: 71
posted April 22, 2005 04:47 AM  
Just some thing else to look at I had the same problem last year I could not get though 2 nigts with out burning the ujoint completely out. I was useing the tough ujionts for (so the say off road use). Look at where they are made these were all made in (JAPAN). If you take the caps off and look at the end of the bearing race there is no slot cut for grease to get to the bearings. (They are junk) loned one to a friend one night it cost him a feature win he was laeding when it burnt. Go find some one who sells ujoints made in (USA) if you still can. Also check to see how much pull bar travel you have I don't like anymore than 1.5". Hope this will help.

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