the dreaded Chinese Puzzle

[urquattro]

> Note that it is just as easy to install it wrong as it is to install it
> right:  No difference in effort to assemble required!   BTDT!!!
>
... I can attest to that as well ... in my case I noticed a definite "snap"
as the inner CVJ locked up, so I knew that something was wrong!  I don't
remember how long it took me to get it back apart!

Marc did a good job of explaining the situation ... if you look at the
"cage" you will see that the part that holds the ball in place has an oblong
shape ... this allows the balls to move radially as the inner and outer
pieces move in and out relative to each other ... and preventing any
rotation between the inner and outer pieces themselves in the process.  I
was impressed when I figured out how the thing worked (I was changing the
inner boots on the Fox) ... especially knowing that other FWD cars like my
Dad's Horizon had a rather funky "tripod" joint that attempted to do the
same thing.  The way I explained it was to say that each of the pieces had
three sets of "V" grooves in them ... when you assemble the joint
incorrectly the "V" in the inner piece lines up with the "V" in the outer
piece and then the two are not free to move back and forth relative to each
other.  When you do this you will find that the balls and cage can actually
move back and forth inside the CVJ, but the inner and outer pieces remain in
effectively one position!  You need to make sure that ball that rides in the
"\" of the "V" on the inner piece lines up with a "/" of a "V" on the outer
piece.  When correctly assembled the cage and balls remains in a single
position relative to the center of the overall joint, and the inner and
outer pieces will move back and forth freely ...

As an engineer and a tinkerer I found the operation of the inner CVJ quite
impressive ... while the outer CVJ is interesting in that it can smoothly
transfer power while allowing so much angular displacement between the input
and output, the joint is relatively simple inside.  I heartily recommend
anyone interested in that sort of thing find an old inner CVJ and see for
yourself how it works.  BTW, I've got a torsen diff in the garage ready for
me to gain a deeper understanding of its workings ... someday ... :-)

Cheers!
Steve Buchholz
San Jose, CA (USA)