CV joint : no gasket - why?

[Bukowski]

I recently learned that 914's have a gasket for the CV joint. maybe 911's have one too, I don't know.

sooooo - why isn't there an official gasket for 944 CV joints?

[v2rocket_aka944]

first immediate thought is that the gasket might serve as a sort of heat isolator on those cars.

a big air-cooled lump bolted directly to the transaxle conducts a lot of heat which would find its way to the axles...maybe the paper is enough to minimize heat transfer from the transaxle to the CV joint/grease.

whereas the 944 has 7 feet of separation from the heat-pump.

[kwikt 911]

Wondered the same..... my 911 has them hmmmm

[dgcantrell]

Audi uses them on their cars. My Audi 5000 has them and it's certainly not air-cooled. Plus any heat is going to be transferred through the bolts anyway. The gaskets are more for keeping the grease from finding its way out under centrifugal force. Why they didn't use them on the 944, I'm not sure but I'm thinking about using them on mine the next time I have to tear down those axles.

[v2rocket_aka944]

The Audi still has the big hot engine bolted to the transaxle, and the bolts only allow limited heat transfer versus the whole face of the stub axle.

You could compare it to the phenolic intake spacers made for some cars - questionable power benefits, but the manifold is much cooler to the touch after a hard run, if that is worth anything.

Not saying my idea is THE answer...just speculation.

[dgcantrell]

They use them on the rear differential also... My 5000 Quattro uses them on the front and back. The manual transmission in the 5000's are the same as the 944 transmission. Not to mention grease is pretty decent heat transfer substance in itself, no?

[djnolan]

According to Clark's: "Over time, the grease in the CV Joint tends to disappear, even on CV Joints with boots that are in perfect condition. Don't ask me where it goes, I don't know."

Has the cause been found?

[v2rocket_aka944]

Some engineer in Stuttgart was drawing the rear axle assembly, sneezed before he drew a gasket, and then forgot what he was doing and sent it off to production...lol

[sausagehacker]

I've had minor evidence of CV grease being flung up onto the underbody, I torque them to spec in a pattern (similar idea as lug nuts) to where the pressure is evenly distributed. I just repack every year, it's cheap and takes 15 minutes for everything. But gaskets would probably help.

[dgcantrell]

I've never seen one that did not eventually sling a little grease out. Gasket or not. But the gasket would definitely be a little bit of help, I would think. I think what causes some of it is that there is usually some grease that gets on the mating surfaces of the bearing and the flange during assembly. It's pretty hard not to if you ask me. Some grease gets in there and even if you torque things down, it still creates a pathway for any additional grease to get out especially under the centrifugal forces of the normal rotation of the bearings.

[thomasryan]

clamping force to transfer torque decreases when the mating surfaces are not clean.

search and read some grady clay threads on cv joints.

[dgcantrell]

Not to mention the fact that grease and oil are designed to prevent surfaces from making contact with each other to start with. :-)

[Bukowski]

interesting, thanks everyone...

[curtisr]

Originally Posted by v2rocket_aka944

Some engineer in Stuttgart was drawing the rear axle assembly, sneezed before he drew a gasket, and then forgot what he was doing and sent it off to production...lol

Hmm, Gesundheit sounds like gasket to me. In English anyways.

Watched Van's CV repack video. He is using one from a 914 and I don't recall any caveat about a washer.

[curtisr]

Originally Posted by djnolan

According to Clark's: "Over time, the grease in the CV Joint tends to disappear, even on CV Joints with boots that are in perfect condition. Don't ask me where it goes, I don't know."

Has the cause been found?

Back in the day when only Campagnolo grease would do for one's bicycle wheels it would drive me crazy how quickly the stuff would dry out. It seemed that the oil release ingredients would evaporate or something. This was true of all of the lithium based greases I tried and then along came Phil Woods and SuperLube. Troubles were over.

[mattdavis11]

I might be dead wrong, but moisture absorption by the gasket could lead to premature failure of the joint. We do have lower heat points on the motor where anaerobic sealant is utilized in lieu of a gasket.

[dgcantrell]

If a gasket absorbs moisture and allows it to enter the place it's supposed to be sealing, it's not really a gasket. LOL However, you could probably get away with smearing a very very thin layer of RTV on the outer 1/4" of the face of the flange and achieve some good sealing results. I might go this route on the old Quattro I'm rebuilding and the 944 next time I have to do any drive line work.

[mattdavis11]

But a gasket can dry out when it is near a heat source. Not much heat near the CV on our cars. See v2rockets' post above.