[Vwdiesel] Spalling on Outer CV Joint

[Gavrik Peterson]

Hagar.

>Take a close look at the chrome ---- is it chromed?

Nope.  I think I am just looking at metal.  The part of the joint that
is exposed to the elements has a thin coating of rust.  Do they
sometimes chrome CV joints?  This one is made by Lobro in Germany.

>It sounds to me that you do not have "Spalling" in the normal
>sense of bearings.

The spalling or pitting I am talking about is deep -- not just a
surface coating that has flaked off.

Looking at the joint (I am talking about the outer part of an outer
joint) I see places where the grooves have an area that looks and
feels rough.  You can place a fingernail into one of these patches and
feel the roughness which is on the scale of sand.  Clearly, a
significant amount of metal has been removed.

I notice that small patches are located near the rim of the groove.
Larger patches always extend from near the rim down toward the groove
bottom.  This makes me think that the spalling starts near the groove
rim and then progresses down as the patch grows.  This makes some
sense because when a joint is delivering large torque the balls load
the side of the grooves.  When the joint is delivering zero torque the
balls just contact the groove bottom.  This may explain why an
assembled joint operates smoothly when you move it by hand, even
though there are rough patches on the sides of the groves.

In the past other joints have had this kind of wear.  I have only
observed spalling on the outer part of an outer joint.  I never see
significant wear on the balls or the inner part of the joint.

>This VW  masterpiece beats them all.

Can't say how VW CV joints stack up as they are the only ones I have
worked on.  They sure have some tricky to machine surfaces in there,
and I must say that I find it amazing, how well they work.

Thanks for the response.


Gavrik Peterson