64BB

well, i have significant premature wear on the outer half shaft u joint on the passenger side. so far no explanation. the spindle seems ok; the spindle bearings seem ok; u-joints are all quality; the half shaft is coirrect and straight etc; still, i am grinding up the outer u-joint. [ i never race the car]
someone suggested that the differential is "loose" and that that "shortens" the shaft which causes too much outward thrust against the shaft which causes the excessive u-joint wear.
so, last night i dropped the half shaft and took a look at the side gear yoke. so far i have NOT measured the end play of the yoke, but it wiggles pretty good and by my eye ball the end play will be .030 or greater.

any thoughts would be very greatly appreciated.

Crazyhorse

What exactly is happening to the U Joint ?
Although the end play of the yolk is probably over the spec I
can't see that causing U joint failure.
When the wheels are on the ground the suspension tends to push
the axles towards the diff anyway.

magicv8

I can't see end play causing anything. I don't have clips on my yokes. They come right out if I unbolt the halfshaft. My joints will last for years IF I don't power shift.
If I do
(just a few)
I replace at least two,
with new,
each year under lifetime warranty from Autozone.
I couldn't resist that. It sounds like you installed dry bearings, powershifted until the needles made an impression on the cross (my favorite), or have squashed them into a hole that isn't round. I have had the same joint fail twice in 12 months, but never sooner. On an SB car I could understand the inner being crushed. The outer has to be pressed into round holes. If the holes are round and you are using a press, the joints are crap. The only OTHER possible cause is HEAT. Are your brakes dragging or are your spindle bearings shot?


[Modified by magicv8, 7:01 PM 5/10/2002]

64BB

magic, your answer about running without clips has been MOST helpful. i measured the end play and it is .048 [a lot], but since your end play is infinite, i guess i don't have to worry about mine. i'm glad i asked the board.
here is the u-joint history in a nutshell:
1-i bought the car four years ago. the right rear wheel was at a bad angle [bottom about three inches away from center; the wheel well space was i inch less than on on the other side]. i thought it was just an alignment problem!!!
2-a shop told me there was WAY too much loose wiggle when the top and bottom of the tire were grabbed and wiggled. they said i need new bearings.
3-i installed new rear bearings [ spindle end play is now .002]
4-same bad tire wiggle after the installation [the old bearings looked good anyway] i drove for a few months with rear tire that was as crooked as before [it loooks like the leaning tower of pisa from behind]
5-started to notice a squeak-squeak-squeak everytime my wheels turned. i thought it was the brakes rubbing. but they were great [i checked them out]
6-i finally dropped the half shaft to re-check the bearings and noticed BIGTIME failure of the outer u-joint. it had worn through the cap and had destroyed the hardened yoke surface. the needles were gone as was the cap.
7-i replaced the half-shaft with a correct brand new one
8-within 1,000 miles there was a grinding when i hand turned the wheel with the car raised
9-the outer u-joint had one frozen and rusted bearing surface [dry inside]
10-i just installed a new u-joint so i will see how long this one will last

ANY ADVICE WILL BE APPRECIATED. THANKS TO ALL.

sideoiler

How about your strut bushings--could they be so bad as to let the negative camber increase severely each time you hit a bump and prematurely wear out the joints?? If they are bad it would cause the looseness at top and bottom you describe.

Chuck Gongloff

Could the trailing arm be bent, causing the severe angle, thus causing the premature U joint wear? I assume you've tried to adjust the camber using the strut rods. If the end of the stub axle is worn, it will cause the upper part of the tire to go more inward. If you think about it, the stub axle and half shaft are both a suspension AND a drivetrain component. The stub axle and half shaft are the only "things" that hold the upper part of the tire "out". Think of the front dual A frame suspension.....one frame above, one below. On the rear.....camber rod below.....half shaft/stub axle above. Hope this helps. Chuck

64BB

sideoiler and chuck, let me clear up some muddy information i gave you. after i installed the correct rear bearings, but before i noticed the massive u-joint failure, that was when i had extreme negative camber [by eyeball at leat 15 to 20 degrees-same as before i replaced the bearing]]
however, after i put in a new half shaft [including the new u-joint], there was a great improvement in the negative camber. it is now about 5 degrees by eyeball. HOWEVER, NO MATTER WHAT I DO TO THE ADJSUTING CAM, I CANNOT GET TO A NEUTRAL OR POSITIVE CAMBER. now you have suggested a potential problem with the trailing arm being bent, or with worn bushings on the strut or with a worn stub axle.
first, what is the stub axle? is that the side gear yoke coming out of the differential?? how could i test to see if there is excessive wear?
second, how can i test to see if the trailing arm is bent?
third, how can i test to see if the strut bushings are worn?
fourth, what sort of things will prevent adjusting to a positive camber, no matter how hard i pound on the adjusting bolt. there is no problem moving the spindle out in order to drop the halfshaft [the cam moves freely]. the problem is getting rid of negative camber.
again, i really appreciate the advice. thanks to all.

Chuck Gongloff

The stub axles are the axles coming out of the differential. The ends are case hardened and "ride" on the pin in the diff. If the ends wear, the stub axle goes further in, increasing negative camber. The stub axles are retained in the diff by "C" clips. The axles can wear so much that they wear down to the C ring, and the ring falls off, getting chewed up in the ring and pinion. Take the half shaft off, and push/pull on the stub axle. I don't know the "spec" for it, but it shouldn't move much. Regarding the trailing arm, eyeball it. It should be "square", not twisted or bent. Sounds like you've got some major problem back there. The bushings in the camber struts are easy to check. When you turn the camber adjusting bolt, the bottom of the rotor/spindle should move inward and outward as you turn the "eccentric" cam on the adjuster. Chuck

magicv8

You will have to get the camber to zero. The yoke is shot if the slinger is about to contact the differential case. The slinger is the large formed sheet metal washer welded onto the diff yoke to protect the diff seal from flying crud.

If the adjusters on your strut rods won't retract them enough, either the adjuster is broken (been there) or the strut rod bushings are shot (been there too). I installed poly bushings in place of the rubber ones. Removing the originals is a PITA - most easily done with a torch (while you hold your nose). To save your original rods and bushings for shows, get the twist adjustable ones from Vette Brakes. The JCWhitney catalog used to occasionally list them on sale. They solve the bushing and the stripped adjuster problems at the same time. I love them. Check the Details link on my homepage (below) to check out their installation on the back of my car.

Are you sure that the new half shaft is the correct length? If it's short, the problem will not go away. Check it against the one on the wheel that looks good. A carpenter's level can be used to set the camber to zero when you locate the problem. Unless your trailing arms are almost rusted out, or have been modified, I doubt that they are the problem.