

| Subject: | Re: Speedo calibration |
| From: | Dr. Rainer Woitok |
| Date: | Wed, 12 Aug 1998 09:51:07 +0200 |
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 ... :-) ---------------------------------------------------------------------- | Rainer M Woitok | Phone: (+49-9131) 85-7811, -7031 | | 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 | ----------------------------------------------------------------------
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