CV Joints

[ROWSC]

I had a persistent thump, thump, thump sound coming from the right rear. I though it was a tire rubbing because it went away when I rolled the lips of the fenders. It came back loud as ever when I took the car to an autocross event. Everyone kept saying it was the CV joints, but that made no sense since they have only a couple thousand miles, albeit many years, on them. So I ordered another tube of Swepco 101 and figured I'd ask you how to diagnosis CV joints.

I just took the axle off the car and one of the outside mounting bolts was missing its head. Could this have been my problem or is it a consequence of a different problem? One thing I noticed is that my car doesn't have the three crescent moon shaped backing plates shown in the Bentley manual (and the PET further confuses that issue by saying there were four of these, but only for the SC/SPM vehicles).

What should I do now?

Thanks, as always!

Rich

[Steve]

Rich,

ALL SC's are supposed to have those curved plates under the CV bolts (2 per side), otherwise the bolt "reach" is too long.

If a bolt head is missing, its likely due to either being over-torqued or a defective fastener.

CV joint issues usually make a clicking noise when worn, , but thumping noises indicate another issue. I would putting the car on jackstands (or a lift) and running it in gear while looking around & listening to everything from under the car to find the problem.

[ROWSC]

I should have noted that the thumping sound only occurs when the car is turning, most notably when turning hard left (sound is from right side).

I don't understand the "two per side" rule. Are you saying that only two of the six bolts holding each joint have this "reach" issue? Is it possible the bolts were bottomed out, leaving the joints tight enough that they seemed solidly mounted but actually loose enough that they wobbled under load? Reading one of the other threads, I realized that there were no locking washers either, furthering my suspicions.

I would like it noted for the record that I installed the new CV joints with the same hardware it came with from the local Porsche shop that maintained the car for years, but that was too stuck up to even talk to me after I got the car...

Thanks Steve!

Rich

[Steve]

[ROWSC]

That's what I assumed when I saw the illustration in Bentley. So, should I:
Replace the broken bolt
Find 12 of these plates (I assume they go on the interior joints as well and I'll want to do both axles)
Pack the joints with another dose of grease
Put it back together with lock washers and see if I've solved my problem?

If so, do you recommend removing the boots to pack grease from that side as well? I was getting some flying grease from where the small end of the boot meets the axle because I didn't know I needed to buy a clamp for that end.

Anything special about the locking washers I need? Pelican sells the bolts for $1.75 and washers for $0.75. Is it something you sell, or is that order too small to mess with at your end?

Rich

[Steve]

[ROWSC]

The mystery continues. I've kept every part I've ever replaced and decided I should double check the old CV joints to see if I mistakenly left off the backing plates (they are $7.50 x 12 @ Sunset after all). No such luck, but I found 24 greasy CV joint bolts in a bag with the snap rings. I went through all my receipts and I have no record of ordering new bolts.

What I find interesting is that the "found" bolts are about 3mm longer (shaft length 47mm vs. 44mm). They have a gray finish, no markings, and 12-point pan head. The ones removed from the car are black, have "TUZ 12.9" stamped on the head, and are 6-point. Should I go back to the originals?

[Steve]

You need to be using the original 6-pt hex, 12.9 grade, socket head bolts here.

[ROWSC]

[Steve]