Date:         Wed, 12 Aug 1998 09:51:07 +0200
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: Speedo calibration
Comments: To: lcarter@cowichan.com
Comments: cc: van <vanagon@vanagon.com>
In-Reply-To:  Msg <B0058669097@www.cowichan.com> of 1998- 8-11 12:15:25 -0000
              from lcarter@cowichan.com
Content-Type: text/plain; charset=us-ascii

Hi Larry and all you other listees,

On Tue, 1998-08-11 12:15:25 -0000, Larry Carter wrote:

> ...
> I have an 87GL, the little number under the VDO is 500.

Hummmm ...  Though I can remember having   read myself that  this little
number specifies the number of revolutions of the speedo cable necessary
to increment the odometer by one, I slowly start to  doubt that (way too
many  different numbers for  otherwise identical set-ups with respect to
measurement systems and tire sizes) ...

> ...
> In my GL the speedo cable (inner) plugs into a square hole punched in the
> left front outer wheel bearing dust cover, from there the cable goes
> directly into the back of the speedometer, there are no gear reductions
> along the way.

Please excuse my impropper wording (and my lack of knowledge of American
technical terms; I'm trying  to catch up, though :-).   What I wanted to
say is that  there is some sort   of simple mechanical gear involved  to
convey the rotation of  the (more or  less) horizontal axle stub of  the
front wheel to the (again  more or less) vertical  speedo cable.  And in
chosing  the  diameters appropriately you  can   do anything here,  from
spinning the speedo cable N times while  the front wheel turns only once
to turning the speedo cable one time while the  front wheel is turning N
times.  And because a speedo is probably  more expensive (and more bulky
to  store)  than  such  a  simple gearing  device,  and because  in some
countries  there  might also be  legal  constraints against exchanging a
speedo (because  of  the odometer) I think   VW has chosen  to have only
rather  few  different types  of  speedos  and  to   do  all the  "math"
associated with miles, kilometers, and tire sizes using different speedo
gear assemblies on the front wheel.

I Hope this clarifies a bit what I wanted to say.

Sincerely
 Rainer

PS: Going on  vacation this  Friday for four  weeks I've  set my Vanagon
list options to NOMAIL (aproximately one hundred messages a day times 28
days would otherwise sum up to having to wade  through almost 3000 mails
just from this list  upon returning  :-).   Thus, if I don't  any longer
engage in  this discussion  (or  any other  discussion for that matter),
it's  not because  I lost  interest,   but rather because I  temporarily
turned to more important things than sitting in my office ... :-)

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| Rainer M Woitok                  | Phone: (+49-9131) 85-7811, -7031  |
| Regionales Rechenzentrum         |                                   |
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