VW type Cv joints

[Steve Demeter]

I have a rather silly question: I believe that the torque is transmitted by the friction between the face of the CV and the flange it is clamped to by the bolts. NOT the bolts.

Therefore, both he flange and the face of the CV should be as clean and free of any lubricant a possible, right?

[stonebridge20]

I have a rather silly question: I believe that the torque is transmitted by the friction between the face of the CV and the flange it is clamped to by the bolts. NOT the bolts.

Therefore, both he flange and the face of the CV should be as clean and free of any lubricant a possible, right?

Yes !

[DSR3]

I'm a bit surprised that I don't see more of these in use.

[Charlie Schmidt]

willing to be proven wrong, but....
I always thought the torque load was handled by the bolts in shear
clean + dry for sure, but only so that you get a good fit
The 2 hole washers are necessary to keep the bolt heads from trashing the flange on the boot
they are hard, so you can torque things properly, and they protect the flange from the bolt heads
if not using the washers, you can't maintain torque value

[Rick Kirchner]

I'm surprised that a similar washer was not developed for the tripod joints.

[DaveW]

I have a rather silly question: I believe that the torque is transmitted by the friction between the face of the CV and the flange it is clamped to by the bolts. NOT the bolts.

Therefore, both the flange and the face of the CV should be as clean and free of any lubricant a possible, right?

willing to be proven wrong, but....
I always thought the torque load was handled by the bolts in shear
clean + dry for sure, but only so that you get a good fit
The 2 hole washers are necessary to keep the bolt heads from trashing the flange on the boot
they are hard, so you can torque things properly, and they protect the flange from the bolt heads
if not using the washers, you can't maintain torque value

Both bolt shear strength and friction are important for keeping things tight.

The way torque is transmitted is similar to the drive pins on a wheel hub. Both clamping load and resultant friction between wheel and hub must be enough to stop any sliding between the two once max torque direction has rotated the wheel against the drive pins. So the pins/bolts handle shock loads (rough shifts, tires skipping over rumble strips, etc.), but friction keeps the assembly from shifting back and forth, keeping it from loosening.

So both pin/bolt shear strength and contact friction are critical in the function of this type of joint. If the pins/bolts did not provide a hard limit to travel, friction alone would not be capable of preventing slippage even with perfectly clean, dry surfaces. If pin/bolt travel limiting was not necessary, we wouldn't need wheel drive pins.

I seal the CV's with RTV between the mating surfaces and any other place grease could leak out, and I have never had any issues of CV's getting loose because of this. GR8 bolts shear strength and clamping-load (18 lb-ft on 5/16-24 screws in my Lobro CV's) provide both sufficient friction and shear strength to do the job.

Caveat on using RTV - see the following post.

[DaveW]

...I seal the CV's with RTV between the mating surfaces and any other place grease could leak out, and I have never had any issues of CV's getting loose because of this. GR8 bolts shear strength and clamping-load (18 lb-ft on 5/16-24 screws in my Lobro CV's) provide both sufficient friction and shear strength to do the job.

A caveat I should have mentioned above that is VERY important when using RTV to seal CV's or any other stressed joint:

The key to making RTV sealing not degrade the ability for the ass'y to remain tight is that the nuts/bolts MUST be fully torqued before the RTV begins to cure to assure RTV is fully squeezed out from contact areas.

If the RTV cures significantly before the fasteners are torqued, and some RTV remains between contact points, that RTV will stress relax, the joint will lose some of its clamping load, and eventually, failure could occur.