Rear u-joint

I keep frying rear u-joints? The last NAPA u-joint maybe lasted 100 miles. I really don't feel much drive line vibration ( the whole CJ5 is a vibration . The angles don't look bad. Every time it's the rear driveshaft u-joint, And it's always the 2 pressed in one's that go. Any idea's??

 

What year and drivetrain is in your jeep? When you say "frying rear u-joints", what does that mean? Are they coming apart, or heating up, or what?

 

Oops! 1975 CJ5, 258, 3speed, dana 20 t-case, dana 30 front axle, dana 44 rear, 3.73 gears, 33x12.5 tires. Paintd desert kaki in honor of our Armed Forces Heoros!

They are getting hot I could smell the grease cooking in this last one, If you keep runing them they will explode. I could hear the first one rattling, so I changed it all the needle baerings where gone, The next one exploded, Had to drive home in front wheel drive. The last one I was coming home and I could smell it, Got out and checked it, it was very hot. Took it apart today and all the needle bearing are gone.

 

Yeah, I greased them, Then put them on and regreased them with the grease gun, But you know grease came out of the 2 ends with the u-bolts but none came out of the 2 pressed in ones. And those are the ones that messed up. I'm wanting to get so synthetic grease maybe tomorrow?

 

types of grease won't make a difference to amount to anything. Not to deal with a severe problem like you have. Are the u-joints binding up? Is the jeep lifted? By binding, I mean does the u-joint make contact with any part of the yoke as it is turning in its arc? If you have a good floor jack and some jack stands, jack it up with the weight still on the axle. ( lift it by the axle, not the frame) then with jackstands in place for safety climb under it and try to rotate the driveshaft. The wheels should spin, but if it binds up try and see where it is binding. Usually there is u-joint to yoke interference.
without jacking it up, sometimes you can tell by driving if there is any bind. When starting off slowly, you sometimes can notice the shifter handle jumping left and right, or back and forth as you drive. This can be an indicator of binding as well. Not always, but it can be.
Check these things out and get back to us.......
Hope this helps.

 

OK thanks, I'll try that after work tomorrow. I took it apart today and it's not the pressed in ones that where messed up it was the 2 held on to the yoke by the u bolts. I noticed the u bolts where alittle loose & the trans stablizer stud was loose also. But I ran out of daylight before I could get everthing back together....

Thanks!!

 

Got everything back together, Checked it out no binding, So I drove it to work yesterday got home oh the ends of the u-joint where hot! I'm guessing Maybe the drive shaft has to be out of balance???

 

Has this always happened since you've owned the Jeep?
If not, then when did it start happening?
Does the Jeep have any suspension lift? If so how much?
Does the driveshaft collapse and extend relatively freely?

Aside from all that, ujoints only work when the angle made at the transfer case ujoint is the same as the angle made at the pinion. Oftentimes, when a Jeep is lifted, these angles may inadvertently change. This is exacerbated in a CJ5 due to the short wheelbase.

Hope this helps,
Eric

 

Took it to 2 different shops Friday, They both think that it is do to the transfercase beening swapped out. Because the from the driveshaft conects to transfercase & the rearend it is not straight in line. There is like a 2 inch difference in them left to right. I thought I was told ounce this in normal in the 72 - 72 CJ's.?? It does have a Dana 20 in it.

It has a lift I'm not use how much. It was lifted when I bought it. I have 33x12.5 on 10inch rims on it. And it clears ok. It startd messing up more u-joints after I tightened the rear end u bolts. I had it for about 2 years or so before I had any trouble with the u joints. When I replaced the first on I noticed that the u-bolts for the springs where a little loose so I tightened them up. That is the only thing I have done to the rear drive line other than take out the drive shaft.

Thanks for ya'll help....

 

I think a 2-inch difference isn't that drastic. I've run way worse for much longer. How tall is it lifted? You should be keeping U-joints alive longer than that. It'll cost you $11 to test it out, but try a Spicer non-greasable 1310 instead of the Napa joint. I swear by 'em. If you blow up the Spicer joint, then you've got some angularity issues.

It's normal for U-joints to get a little hot. I've had 'em where you couldn't keep your finger on them and they last longer than what you're saying. How tight are you gunning down the U-bolts? They shoudl be snug, but you can crush the cap and cause the needle bearings not to work if you tighten them down too much.

 

I have the same offset between the t-case and rear axle. I have not had any problems with u-joints. There has to be another culprit.

 

Where would I get a Spicer non-greasable 1310?? I'll try them & maybe wedge the axle to take care of the up-down angle on the u-joint..
Tryin to get it ready to drive to tellico in April!!

So the left-right angle being off is normal.

Thanks for all the help!!!!!

 

Do you have a CV joint at the Tcase. If not you'll want the same angle at the rear axle as the tcase. Also like said above these dont have to be super tight just good and snug.

 

On it's got U-joints at both ends.

 

Couple of Ideas...
1. Is the driveshaft out of phase?
2. Are the yokes bent.
3. are the angles from from the transfercase to the driveshaft and the driveshaft to the rear end the same?

 

Well after much talking & reading. I made a 3/4 t-case drop kit. I can actualy touch the u-joint after drive it to work. It's still warm but not scalding hot. Alot of the vibration is gone know.It's kinda comes and goes. So I think I'm gonna put 2 or 3 degree shims on the axles.