Date: Sun, 19 Jun 2005 22:10:38 -0500
Reply-To: Stan Wilder <wilden1-1@SBCGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1-1@SBCGLOBAL.NET>
Subject: Re: Speedometer -- the straight scoop
Content-Type: text/plain; charset="iso-8859-1"
Speedometer error is a common thing with all cars.
The variables are caused by different tire sizes, wear and resistance in
speedometer parts.
My 92 Crown Vic registers 75 when it's doing 70 because I use a lower
profile tire that OEM size.
My 86 Oldsmobile reads right on the money even though it's 19 years old,
can't say why.
My 76 Porsche had built in speedometer error that was mentioned in the
owners manual but with the conversion to 15" wheels and late generation
tires it seemed to be exactly right when reading a stop watch against ten
mile markers or just the one mile intervals.
Stan Wilder
Engine Ceramics
214-352-4931
www.engineceramics.com
----- Original Message -----
From: "Mike Collum" <collum@VERIZON.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, June 19, 2005 9:02 PM
Subject: Re: Speedometer -- the straight scoop
> The speedometer in my 2000 Beetle reads 67 when the GPS says 63 (4 miles
> per hour difference at that speed ... on the safe side).
>
> I used the GPS in my '85 Westy, during the trip to BusFusion, and (Boy
> was I surprised) the GPS consistantly showed 66 whe the speedo said 65.
> Just the opposite of what it "should" be. At least now I know.
>
> There are speedometer shops that can calibrate them but I don't know
> what they charge.
>
> Mike
>
>
>
> Michael Elliott wrote:
> > I know this is a done-to-death subject, but I searched the archives and
> > didn't turn up what I was looking for:
> >
> > The facts, as I know them:
> >
> > According to yesterday's "speedometer check" signs posted by the side of
> > Interstate 8, my odometer is a smidge optimistic: when I had traveled 4
> > miles, the odometer read 4.1 miles. Close enough for me. 2.5% error.
> >
> > The speedometer reads pretty low. According to the "Your Speed Is"
> > automated trailers with giant speed displays parked on the streets AND
> > according to my GPS, the speedometer is WAY optimistic: when I'm going
> > 65mph the speedometer thinks I'm going 75. This is a fixed percentage:
> > as I go slower, the mph error is smaller but the percentage error is the
> > same. About 8 - 9%.
> >
> > So the odo is acceptably accurate, the speedo is not so accurate.
> > Anything a fellow can do other than just mentally correct the speedo
> > reading?
> >
> > --
> >
> > Mike "Rocket J Squirrel" Elliott
> > 71 Type 2: the Wonderbus
> > 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> > Carlsbad, CA
> > KG6RCR
> >
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