Stuborn CV's

[pcar9119]

Has anyone had the problem of the axles coming loose on them?
The bolts on my axles kept backing out all last summer. I was constantly tightening them about every 2 weeks. What a major annoyance. I finally got them to stay tight with lock washers from my work, but I'm not convinced that is going to fix the problem.

[yelcab1]

Yes, I did but that was when I did not install them correctly. My guess is your threads and bolts are all worn out. I propose that you chase them with a tap and die, then reinstall with a touch of blue loctite, and torque to specs and then all will be good.

I have never had one back out after that regimen. I do not use lock washer, or schnorr, or safety wires.

[jrumiano]

The problem with the CV bolts backing is the CV grease getting on the threads. You need to clean the threads spotless of grease using brake cleaner and q-tips. Do a search on this site there is a long post all about CV joints and bolts.

Good luck,
John

[RWebb]

Originally Posted by yelcab1

Yes, I did but that was when I did not install them correctly. My guess is your threads and bolts are all worn out. I propose that you chase them with a tap and die, then reinstall with a touch of blue loctite, and torque to specs and then all will be good.

I have never had one back out after that regimen. I do not use lock washer, or schnorr, or safety wires.

- Do the above last.

Do what John said, and be sure to use NEW Schorr washers on them.

If there are no moon plates then buy some.

Inspect the bolt threads and the inset wrenching fixture on your bolts. If they are OK, then clean carefully and reuse. If not OK, buy new bolts, aka cap screws.

[Gunter]

Originally Posted by pcar9119

Has anyone had the problem of the axles coming loose on them?
The bolts on my axles kept backing out all last summer. I was constantly tightening them about every 2 weeks. What a major annoyance. I finally got them to stay tight with lock washers from my work, but I'm not convinced that is going to fix the problem.

No lock-washers is part of the problem.
CV's are not stubborn, they work fine if torqued correctly with Schnorr washers as intended by Porsche.

It would help if you let us know what type/year?
Four 10mm bolts, or six 8mm bolts?
Moon-plates?
What torque are you using?
Going cross-wise with a pre-torque first or?

[pcar9119]

It's a 79 SC. It's Six bolts, 8MM, and I'm using lock washers and no moon plates. It didn't have any on there so I didn't install any. I haven't had any problems since i put Knew bolts and lock washers. Maybe that will fix my problem.

[RWebb]

split ring lock washers are not adequate - must use Schnorr

need moon plates too - regular sheet metal cup forming the CV housing is not adequate

[dvkk]

In extreme cases, the threads in the flanges get wobbled out. If that has happened, no amount of tightening or loctite will give you a reliable connection. Replacement is necessary.
The initial cause of the bolts backing out is improper torque. The CV bolts take a lot more torque than most mechanics are used to. A torque wrench is manditory.

[911Etarga]

How do you know when the bolts are comiing loose, other than checking? is there a clunk, or any other sound?

[otto in norway]

The bolts for the CV's; are they not "stretch-bolts"..?
I thought they were intended to get torqued properly once, and that one time they will stretch a certain amount, keeping a constant pull on the two surfaces.
I was told that old bolts should be replaced because these caracteristics change over time.
Anybody know for sure?

[Porsche_monkey]

They are torqued, so technically they aren't stretched. I think.

All bolts are stretched, but stretched usually means torque to xx ft-lbs then rotate yyy degrees. (Like a head bolt).

Still, in this application I would consider replacing them if they have been a problem.

[pcar9119]

The first time time they came loose and me I was racing a car down the highway and the axle came off. Wow. What a noise. After that i was checking them routinely and noticed they were backing out. So i took them all out, replaced all the bolts, chased threads, and reinstalled the new bolts and washers. I never noticed any vibrating or noises until the axle cam off at 100mph. Thanks for all the info guys. I love this forum.

[RWebb]

Originally Posted by otto in norway

The bolts for the CV's; are they not "stretch-bolts"..?
I thought they were intended to get torqued properly once, and that one time they will stretch a certain amount, keeping a constant pull on the two surfaces.
I was told that old bolts should be replaced because these caracteristics change over time.
Anybody know for sure?

- no.

- Jim Sims said no to both above & he should know -- search on his name and CV (use google) or name + joint + bolt in this search engine

[RWebb]

Originally Posted by 911Etarga

How do you know when the bolts are comiing loose, other than checking? is there a clunk, or any other sound?

- check BEFORE there is clunk!!

I re-torque after re-installation + 100 miles; same on wheel lug nuts.

There is a long thread on all CV joint issues - started by Randy Cecale.

rececale
or
rcecale

[Zef]

Lockwire them, you'll never think about'em thereafter.

[RWebb]

a search will reveal why that is not a great idea....

[Gunter]

Originally Posted by pcar9119

It's a 79 SC. It's Six bolts, 8MM, and I'm using lock washers and no moon plates. It didn't have any on there so I didn't install any. I haven't had any problems since i put Knew bolts and lock washers. Maybe that will fix my problem.

Keep an eye on it.
What torque are you using?
8 mm need 29-30 ft-lbs
Pre-torque first all around, then the final.
These Allen bolts should be 12.9 tensil strength and they don't stretch.
Split lock washers are not the best for this.
Are you using gaskets?
Or metal on metal?