Rainer:
There have been about half-a-dozen people on the list who have tried to
re-build their driveshaft by replacing u-joints.  All who have reported back
(3, to my memory) had the same result as your friend.  the seem to get the
right u-joint, they seem to get it balanced properly by competent people,
and all seems fine when they reinstall it....but fairly soon thereafter, the
vibrations return.  I know one guy in Conn. (Tim) had the shop re-do
everything 3 times, trying digfferent joints, experimenting with shims,
etc., all to no avail  Budd Premak had the same problem.

Two others on the list recently reported having replaced u-joints and
re-balanced, and i mentioned to one the history above....but they have not
reported back on the results.

I thought you might be interested in this background info.  Sorry i can't
help with the techinal info you seek.
steve
p.s. will you guys who recently rebuild your drive shafts let us know how
they are holding up.

"Dr. Rainer Woitok" wrote:

> Syncronauts,
>
> recently    another German  Syncro   driver  contacted  me  because he's
> permanently having problems with his drive  shaft.  The viscous coupling
> was replaced due  to the  grooves  where the  input shaft enters   being
> totally worn  out.  Later he observed  severe vibrations which he traced
> back to the drive shaft.   He removed it  and took it  to a special shop
> for balancing.  After putting the drive shaft  back in everything seemed
> normal for  a few weeks, but  then the vibrations  were back.  Currently
> he's driving with the drive shaft removed.
>
> Some months ago we had a discussion on this list about universal joints,
> and I faintly remember that at least one  person mentioned that when you
> mount the u-joints onto a shaft the wrong way you're into trouble due to
> the different rotational  speeds occuring at the  different  ends of the
> shaft at different times and thus placing severe stress on the material.
>
> I've never yet disassembled my drive shaft, so my  question here is: can
> one mount the  u-joints on a Syncro's drive   shaft the wrong  way?  And
> what has a Syncro's drive shaft  with correctly mounted u-joints to look
> like?  And could a wrongly assembled drive shaft cause these vibrations?
> Or should he check for other causes?  Which ones?
>
> Any input will be greatly appreciated and passed on to the owner of said
> castrated Syncro :-)
>
> Sincerely
>  Rainer
>
> '89 Caravelle GL Syncro 16"
>
>  ----------------------------------------------------------------------
> | Rainer M Woitok                  | Phone: (+49-9131) 85-27811,-27031 |
> | Regionales Rechenzentrum         |                                   |
> | Friedrich-Alexander-Universitaet | Fax  : (+49-9131) 30 29 41        |
> | Martens-Strasse 1                | Telex: d 629 755 tf erl           |
> | D-91058 Erlangen                 |                                   |
> | Germany                          | Mail: Woitok@RRZE.Uni-Erlangen.DE |
>  ----------------------------------------------------------------------