CV Joints?

[Mike H]

I'm developing a speed related thump, thump, thump when pulling away from making a right hand turn. It comes from the right rear of the car and it goes away by 20 mph. Am I correct in assuming CV joint(s)? I haven't had a chance to crawl under the car to take a peak at the boots yet (sub freezing temps drain the motivation to lay on the garage floor).

If I need to replace them, is it better (less hassle) the just buy a new halfshaft? Does BMA carry them or is their another preferred supplier?

Thanks,
Mike

91 535iM

[Brandon J]

Hehe, I just replaced a halfshaft b/c of a bad CV joint. You should check for play in the joint. My CV boots were still good, but the joints were bad. Upon initial start, the rear would thump/clunk until the joint caught up. I also noticed some thumps over bumps. You might also hear or feel a thump when letting off the accelerator pedal (while keeping it in gear)

1. I raised the rear and put it on jack stands.
2. Then I put the tranny into neutral and released the parking brake
3. I then turned one rear wheel to check for play. You basically can feel and hear when the CV catches. Turn one way, then the other, then back and forth.
4. If there is excessive play, or you find that one has a lot more than the other, then you know it is a bad CV.
5. If bad, unbolt 6 bolts from each side, remove old and install the new halfshaft. If you use the old bolts, use loctite.

[Scott H]

BMA has them available.....comes with new bolts. Not too expensive either. Easy swap

[Mike H]

. . . I'll crank the heater up in the garage this weekend and check it out.

[Unregistered]

I thought I had a bad cv-joint on my '89 525i (224,000 km) a year ago. Clicking noises started on left turns, then progressed to constant knocking over a couple thousand kms. Sounded precisely like failed cv-joints that I had experienced years ago on a Mazda GLC/323 and a Porsche 914.

Bought a used half-shaft from the local BMW wrecker and swapped first one, then the other rear half-shaft. No change in the racket. Then got my daughter into the car with me and asked her where she heard the noise from. She placed it under the middle of the car, between the front seats. From my RHD drivers position it had sounded like it was coming from the left rear axle.

Found that the rubber transmission mounts supporting the rear of the transmission had collapsed. This allowed the driveshaft to drop just enough to allow the u-joint to hit the topside of the heatshield over the exhaust. Initially the noise only occurred in left turns as the drivetrain twisted, but as the rubber mounts collapsed more it became a constant knocking sound - exactly like a failing cv-joint sounds.

Hint - the two rubber tranny mounts are considerably less expensive than even a used half-shaft. And the effort of breaking loose the 8mm hex bolts on the half-shaft was a real grunter. Had to chase down the Snap-On guy to buy the extended hex socket to use with my breaker bar, because I twisted off three common steel Allen key wrenches trying to break loose the first bolt.

A couple other E34 owners on the alt.autos.bmw usergroup found this same problem, after first thinking they had a failing cv-joint.

What's worse? Working under a car in a cold garage in Feb in the Northern hemisphere, or on the driveway in a hot Southern hemisphere Feb... I've done both, it's a bitch either way!

Bill K. in Sydney, Australia

[BigKriss]

Thanks Brandon for finding me this link. The problem in my car is exactly the same as what the OP stated. My tranny mounts are fine and I can't see any wear in the boots.

This post should go in the achives.