Date:         Thu, 10 Dec 1998 15:19:09 +0100
Reply-To:     "Dr. Rainer Woitok" <woitok@RRZE.UNI-ERLANGEN.DE>
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Dr. Rainer Woitok" <woitok@RRZE.UNI-ERLANGEN.DE>
Organization: RRZE (Regionales Rechenzentrum Erlangen)
Subject:      Re: Viscous Coupling Test
Comments: To: Per Lindgren <lindgre@online.no>
Comments: cc: vanagon@VANAGON.COM
In-Reply-To:  Msg <36703718.3BC2EAC8@online.no> of 1998-12-10 13:03:21 -0800
              from lindgre@online.no
Content-Type: text/plain; charset=us-ascii

Per and all the others,

On Thu, 1998-12-10 13:03:21 -0800, Per Lindgren wrote:

> ...
>        It has to give some to be operatable at normal road conditions, or else VW
> would have to replace all VC within the first year. If it cant cope with
> differently worn tires, it would lock totally at the smallest turn of the steering
> wheel, not at full turn as it does now.

Mind you,  I'm not the  designer of the  viscous coupling, rather I just
repeated what  I  was  told  by  generally pretty  knowledgable  people,
syncro-wise.  And  there is an  obvious difference between the VC having
to accept different rotational  velocities between its input  and output
side for  a few seconds  while cornering and  then having ample  time to
cool down again or the VC being strained  constantly because there is an
inherent difference in rotational speed between the  front and rear axle
due to differing tire circumferences.

Different rotational velocities in  the VC produce heat  and the heat is
what makes the silicone in the VC stiffening and transfering more torque
from  the input to the  output side.  For the VC  to yield, for instance
while cornering, it's important that  the heat is dissipated faster than
it is produced and that the heat is not produced over a prolonged amount
of time.

Hope this clarifies things a bit.

Sincerely
 Rainer

'89 Caravelle GL Syncro 16"

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| Rainer M Woitok                  | Phone: (+49-9131) 85-27811,-27031 |
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