CV joint gasket count?

[Danny_Ocean]

According to our host's order page, a '79 SC requires two CV joint gaskets (total). Yet, when I removed one axle/CV joints this afternoon, I counted four gaskets. (one on either side of each CV joint...which equals 8 per car). So...can anyone tell me which is it?

[pete3799]

IIRC mine took 2 for each CV. Total of 8 for both sides (4 CV's)

[Danny_Ocean]

Yes, that's what I counted today when I disassembled everything. It looks correct, but the parts manuals only shows two per axle. Also, I went to order new gaskets and it shows "2" required...

[Grady Clay]

I suspect this is ‘confusion’ over what the operation is:
Only two are required if you install the engine and transmission, not having removed the axle assemblies.

Also, some 911SC axle assemblies have the outboard CV joint friction welded to the stub axle. This does not use a gasket here.

‘Normally’ each CV joint uses one gasket. That gasket is between the CV joint and the flange (stub axle and transmission). I have never seen a gasket between the CV joint and the tin boot cover. When there is a tin end-cap, no gaskets are used.

Are you guys seeing a gasket between the tin boot cover and the CV joint?
Is there a recess for the gasket?
Where is the recess?

There are at least four different gaskets:
There are ‘outside’ gaskets for the 108 mm CV joints 1969-‘73
There are the small ‘outside’ gaskets for the 914.
Starting about 1974, the gaskets were moved ‘inside’ the CV joint bolt circle.
There are ‘inside’ gaskets for 100 mm and 108 mm CV joints.

911SC usually use the 100 mm ‘inside’ gasket.

When installing CV joint gaskets, it is critically important that no part of the gasket get between the metal-to-metal contact surfaces of the CV joint and the stub axle flange or transmission flange. These surfaces must have perfect contact and be grease-free.

It is the metal-to-metal contact surface that transmits the driving torque, not the CV joint bolts. The bolts only serve to provide the contact pressure. If the contact surface slips (gasket piece, grease or not tight bolts), the bolts take the drive torque and will break.

While this is a long thread, it is VERY WORTHWHILE to read and study it start-to-finish.
Reconstructing Constant Velocity (CV) Joints

Best,
Grady

[Danny_Ocean]

Thanks for the info, Grady.

I have 100mm CV's. I do not have the "tin plate", but a thick flange (at least 1/4" thick) that the bolts seat on. This thick flange is part of the CV boots. My boots were torn, hence the replacement.

So....upon disassembly, I discovered four gaskets per axle...one on each side of the CV joint(s). And yes, I would describe these as "inside" gaskets, as there is a recess in the trans flange that contains the gasket. There also appears to be a recess in the thick flange that holds the boot.

There are deep grooves/pitting on the joint surfaces, so I'm going to replace with new, in addition to new boots/flanges.

And yes, I was up to 2a reading that thread. I have it memorized.

[Grady Clay]

Danny,

Can you post some images and measurements of these flanges?

What is the material? Aluminum or steel?
What OD?
Exactly how thick? (±0.01 mm)
How deep is the recess for the gasket?
How long are the CV joint bolts?
Were there Schnorr washers and/or ‘moon plate’ washers?

Show your transmission axle flange and stub axle flange surfaces.

I need to read all the axle/CV joint threads and write a summary with links on the ‘reconditioning’ thread.

Best,
Grady

[Danny_Ocean]

I can post pics tomorrow.

The flanges which are integral to the boots appear to be steel. The diameter matches the CV joint, so I'm assuming 100mm. Thickness is appx. 5mm.

The recess appears to be deep enough to contain the gasket.

I'll have to measure the bolts when I return to the shop tomorrow.

No Schnorr washers, or moon clips, just flat washers (only on tranny side...no washers on wheel side). Axles have been in place a long time. I haven't touched them since I purchased the car (2006), and only God knows how long they've been neglected.

The issue with all the CV threads is you don't always know what year set-up is being discussed, so amateurs (like me) get confused as to what is what.

Will post detailed pics tomorrow and thanks again for your effort!

Originally Posted by Grady Clay

Danny,

Can you post some images and measurements of these flanges?

What is the material? Aluminum or steel?
What OD?
Exactly how thick? (±0.01 mm)
How deep is the recess for the gasket?
How long are the CV joint bolts?
Were there Schnorr washers and/or ‘moon plate’ washers?

Show your transmission axle flange and stub axle flange surfaces.

I need to read all the axle/CV joint threads and write a summary with links on the ‘reconditioning’ thread.

Best,
Grady

[Danny_Ocean]

OK...here are the pics:

Output shaft showing recess for gasket...



Wheel-side (stub axle?) showing recess for gasket...



CV boot/flange unit showing recess for gasket...



Wheel side boot/flange...



Torn/separated CV boot/flange indicating thickness of flange...



Pic of "good" boot/flange unit...

[Danny_Ocean]

Bolts are M8x50

[euro911sc]

Mine were exactly the same.


But I forgot the gaskit on the inner side boot flange to CV. No big deal. This is the only part of the car I actually use RTV. If you smere a skim coat at the flange to CV and CV to stub axel/trans you will have no CV grease leaks. Easy to remove as well if you make sure it is just a skim coat! Don't lather it all up do this after you are all torqued down.

[Danny_Ocean]

Cool...so I'm not alone! Were you able to find new integrated boot/flanges with the "thick" flange?

[euro911sc]

Yeah I just ordered them from Pelican last month. $10 each or so. 4 new CV joints as well. New bolts from my box'o CV bolts (bought in '96 and I'm finally getting to the end!!) and some new schnoor washers I bought in the FS pages last year. I have not driven on them yet, but all that is left is rear alignment. I'm confident there will be no issues.

-Michael

[euro911sc]

Link to Pelican Part ~$11 each. Easy :P I used the Swepco Moly 101 they sell as well.

Porsche 911 & Carrera Axles & Bearings - Page 1

[Danny_Ocean]

That's the one I had my eye on. Also wondering how much better the $31 boot is...?