Date:         Sat, 4 Dec 2004 10:25:26 -0600
Reply-To:     John Rodgers <inua@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <inua@CHARTER.NET>
Subject:      Errors in CV Rotation Article at Volkscafe website
Content-Type: text/plain; charset=windows-1252; format=flowed

I don't want to set off a firestorm here. Just trying to sort out CV
rotation.

Sam Walters prompted me to have a look for myself at the Volkscafe article.

I took a look at the article find the article to be really well done.
Extremely informative. Volkscafe and Ben McCafferty's efforts are most
appreciated.

However, in the part of the article on the discussion about CV bearing
rotation I perceive errors. I have double checked it, and I set up a
model to analyze it, ( axle with bearings marked with arrows indicating
direction of rotation) and I still came up with the conclusion that
there are some basic errors in the assumptions. If I am wrong, if I have
missed something, I hope someone will clarify it for me.

Credits to: http://www.Volkscafe.com and Ben McCafferty
(for the whole article - http://volkscafe.com/main.jsp?pa=ip&ip=1150562894 )

* Constant Velocity Joints (CVs): Diagnosis, Maintenance and Replacement*
By Ben McCafferty

*Quote:*
"CV's take wear on one face of the ball hubs only (except when you drive
in reverse), so they can be made to run in the opposite direction to
extend their life. There are two ways you can accomplish this. Assume
you’re looking at the back of the van, and the CV's are labeled with
letters, like this:

/A------B Transmission C------D/

You can move the axles so that the letters now read:

/C------D Transmission A------B (option 1)/ OR
/D------C Transmission B------A (option 2)/

These two configurations will result in the forces being applied to the
CVs being reversed. Note, however, that the following configuration will
NOT reverse the forces applied to the CV joint rotation:

/B------A Transmission D------C/

In other words, if you move the axles to the other side of the van, the
forces being applied to the CV's will be reversed. If you keep them on
the same side of the van, they won’t. On a Syncro Vanagon, since the
outer front CV's are not interchangeable with the inner front CVs, the
front axles must be rotated according to option 2 above."

*End Quote!*

Given that the goal is to reverse rotation;

it follows

Option 1: Incorrect
Analysis shows this course of action results in no reversal of
axle/bearing rotation. It remains in the same direction.

Option: 2: Correct
Analysis shows this course of action to result in a reversal of
rotation. Note that the axle shaft assemblies AB and CD were flipped 180
degrees for this configuration.

Refer again to the diagram:

/A------B Transmission C------D/

Quote:
"Note, however, that the following configuration *will NOT reverse* the
forces applied to the CV joint rotation:

/B------A Transmission D------C"
/

The above statement is incorrect.

The above configuration *will reverse* the direction of rotation of the
bearings. Note that B-A has the same direction of rotation as B-A in
Option 2 - which is correct, as does D-C have the same rotation as D-C
in Option 2 - which is correct, by virtue of the fact that the shafts
have been flipped 180 degrees.

I believe it is easy to get confused on this "CV Direction of Rotaion"
issue, and this discussion above is an example of my point.

It is my hope that this has helped to clear the air a bit on the subject.

In summary the following configurations result in reversal of rotation.

Original:
/A------B Transmission C------D
/

/Reversal configurations://
B------A Transmission D------C
/D------C Transmission B------A

//

Regards,

John Rodgers
88 GL Driver