Reconstructing Constant Velocity (CV) Joints

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Cross pollination as to joint failure. Could have lost a MFI car in slightly worse situation.
Snap! Pow! Vroom!!! Clunk,clunk,clunk... gosh, now what!?!?!?

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Spring is here!

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Potential moonie source:
https://socalautoparts.com/product/cv-joint-hardware-install-kit/

https://socalautoparts.com/product/cv-joint-lock-plate/

[donporfi]

Do you know if the lock plates (moon plates) for the 8mm bolts are available. I cannot find those.
All I found were the 10mm ones.
Tried to look for p/n 901 332 191 00, according to what I read in this post that is the old 8mm lock plate.
Do you have a part number for the late 8mm Porsche lock plates ?

[pmax]

Don't think Porsche specified moon plates on the 8mm. I bought some from empi if I recall but ended up not using them.

[midnight911]

Look for EMPI 875081. Found one at amazon. https://www.amazon.com/Empi-Type-Torque-Washer-Buggy/dp/B003KKF8N6. I've been using these with some success. I sourced them from local parts shop who has lots of VW bug/ baja parts.

[David Inc.]

So I just put the available axle assemblies from Pelican on my '82 SC and I'm unsure of the gasket situation. On both my differential and wheel hub flanges I had recesses for gaskets, but no recesses on the axle flanges. I also did not receive any gaskets with the axles. On top of that, I didn't have any gaskets on the differential flanges but did have them on my wheel hub flanges (though one was mostly chewed up and displaced), and it was the wheel hub flanges that were leaking!

Reviewing this thread and others I figure I'm mostly okay without the gaskets, but what am I risking here?

Also I didn't use lock washers or moon washers as I didn't have them before, but am diligent with proper torquing and surface cleaning. I'll also check them before too much driving.

Here's the link to the axles I bought: https://www.pelicanparts.com/More_Info/92333203302M60.htm?pn=923-332-033-02-M60&bt=Y&fs=0&SVSVSI=0798

[RWebb]

no Schnorr lock washers is the big problem

get some moon plates too

then remove 2 cap screws at a time and add them

you can do w/o gaskets

[David Inc.]

Not to be too can-of-wormsy but I had them on without lock washers and moon plates since I last dropped my engine and they were fine and dandy, nothing ever backed off. Unless the clamping forces are way out of line with the new ones vs the old I wouldn't expect problems under appropriate torque.

When I popped the old ones off they were all nice and tight, too, after even a few HPDE events and ten thousand miles.

[Walt Fricke]

David - I am with you. I've had CVs off and on way more often than about anyone short of having a shop or the like. Eventually got to set and forget, never an issue.

Randy, though, ever the scientist, has told us he once did an experiment - he left off the (new) Schnorrs on one or two bolts. After a while checked things. The one(s) without the Schnorrs had loosened. So he has a pretty strong basis for recommending them. If that had happened to me, maybe I'd feel the same way.

But it hasn't, so I don't. Brain perhaps permanently damaged by Caroll Smith's engineering explanation of bolts in his book on fasteners.

It is pretty hard to see what the moon plates add - just a thick washer. The CV is basically incompressible, so you don't need to spread the load on it. The boot flange/holder is different, thin sheet metal of no special hardness - if, like me, you don't use any washers at all, it squishes some, more as there is more R&R going on. But this has never caused a loss of tension on the bolts for me. And Porsche, at least for some periods, gave up on moon plates.

Oh - if you use moon plates, you need longer bolts. It would be a good time to switch to the 12 point variety, though you can't get the 12 point socket part at your local Home Depot.

But removing and retightening a bolt or two isn't going to damage whatever grease seal you have, so you are good to go.

Just drive it. When rechecking the torque on the bolts after some miles - a hundred or so? - look to see if you have grease coming out. If you do, wipe it off carefully, and wrap the whole CV with silver body tape. It will extend over the flanges, and a bit more, but most importantly will cover the parting lines, so to speak. You usually can find this at places which sell automotive paints and body repair stuff. Or, doubtless, off the Internet.

That should keep the grease from getting out, if any tried.

There is another thing which is worth doing, but may be difficult on these axles. If you put a small tube, like half a brake cleaner spray can red little tube, under the rubber where the boot seals to the axle, you will prevent the side to side motion of the axle and CV inner - and there is such motion - from creating air pressure inside the CV and boot. No pressure to try to make some grease ooze out is good. Since I just use zip ties, not the metal clamps, on my boots, this is simple to do. But a determined guy could figure out a way to do this.

[David Inc.]

Thanks for the feedback. What did Smith say about bolts in his fasteners book? I haven't read it.

[RWebb]

Originally Posted by Walt Fricke

Brain perhaps permanently damaged by Caroll Smith's engineering explanation of bolts in his book on fasteners.

It is pretty hard to see what the moon plates add - just a thick washer. The CV is basically incompressible, so you don't need to spread the load on it. The boot flange/holder is different, thin sheet metal of no special hardness - if, like me, you don't use any washers at all, it squishes some, more as there is more R&R going on. But this has never caused a loss of tension on the bolts for me. And Porsche, at least for some periods, gave up on moon plates.
...

I read that book too, but apparently it damaged a different part of my brain...

There is an old post by Grady Clay about the advantages of the moon plates, but I don't recall what that adv. was.

I do recall that he thought they dropped them as a cost-saving measure when under financial duress in the 1980s...


A good Covid project for someone would be to search up all the posts by Grady and collet them into a bible...

[RWebb]

In Screw to Win, he said a LOT of things - I photocopied a couple dozen pages from the book that were of particular interest. I was going to post excerpts for the late, great Jim Sims to comment on, but I lost them and he died. Another compilation exercise for someone would be to search up his posts...

Here is one item:

"safety wiring will contribute virtually nothing to the task of preventing a bolt from loosening to the point where effective levels of residual stress disappear"

- Caroll Smith

[Quasimoto]

Originally Posted by RWebb

There is an old post by Grady Clay about the advantages of the moon plates, but I don't recall what that adv. was.

Post #9 - Are 'Moon Plates' necessary with CV joint replacement?

I find it interesting that my 2014 Cayman has them...

[Walt Fricke]

Buy the book: Nuts, Bolts, Fasteners, and Plumbing Handbook, Carroll Smith (RIP). Sure to be still in print.

[David Inc.]

I'll look for it, thanks. I very much enjoyed Tune to Win so I'm interested in more of his content. That mix of deep experience laid over an engineering foundation is a real treat.

[safe]

Originally Posted by Quasimoto

Post #9 - Are 'Moon Plates' necessary with CV joint replacement?

I find it interesting that my 2014 Cayman has them...

You need a thick washer when the boot flange is flimsy.

BTW, a friend lost both drive shafts in his Cayman ~1200 miles after having the gearbox replaced at a Porsche Center....

[nene]

YEA,

I am drilling holes in the bolts to tie them with SS wire that holds all of this together, since I am replacing two boots!

[winders]

Safety wire is really not worth the effort. It won't stop the bolts from loosening to the point where clamping force is lost.

[Walt Fricke]

Someone - Smith? - also said safety wire just means the bolts won't fall off when they get loose. Might be valuable in some applications where the shear strength of the bolts is what matters (like, say, a seat belt mount), but not for repetitive stresses. Rod bolts, for instance, don't have their nuts safety wired. And properly tightened don't come loose, either.

Of course, well done safety wiring looks impressive. And it is required for lots of aircraft applications, whether valuable or not. But a lot of extra work for no gain.