John,
Maybe I'm missing something here, but would your calibration procedure not
have to assume that the "other car's" speedometer is correct? I can imagine
all sorts of arguments as to whose speedometer is right if there is a
discrepancy.
Around Winnipeg and on the prairies, there are country roads at one-mile
intervals (even though we have gone metric in Canada; it's hard to move
these country roads to one-kilometre intervals). I have calibrated my
speedometer by having a passenger time the distance traveled between a
number of intersections with these country roads. Most US Interstates have
mileage markers and you can use them to measure the time traveled over a set
distance.
At a speed of 60 mph, you should cover 10 miles in ten minutes. Assuming a
one-second delay due to poor reflexes, this method would give you an error
of 1/600 or 0.16%. This is much less than the error in reading the
speedometer.
Chuck Vandergraaf
Pinawa, MB
'52 +4
> ----------
> From: John T. Blair[SMTP:jblair@exis.net]
> Sent: Monday, July 20, 1998 4:22 PM
> To: morgans@Autox.Team.Net
> Subject: Re: Speedometer calibration
>
> At 06:05 PM 7/19/98 EDT, you wrote:
>
> >My neighbour and I were exercising our Morgans on the highway last week
> >at what seemed to me to be a legitimate speed when we came upon a
> >gendarme parked on the median. My friend slowed dramatically.
> >Afterwards I asked why he had slowed when we were doing only 65. "We
> >were going close to 80" he replied. I had always thought my speedo was
> >reasonably accurate.....
>
> John,
>
> Are you sure that it was your speedo that was off? Before you go nuts
> trying to get your guage calibrated, take another, late model car, out
> and chase it. Instruct the driver of the late model car to signal you
> with 5 fingers and then a fist at 50 mph. Then when you wave back at
> him, have him move up to 55. Again signal you with 5 fingers flashed 2
> times. Repeat this procedure for 60 - 1 finger held horizontally and a
> fist, and 65.
>
> This will let you know that it was YOUR speed o that was off and not
> the other Morgan you were chasing.
>
> John
>
> John T. Blair WA4OHZ email: jblair@exis.net
> Va. Beach, Va Phone: (757) 495-8229
>
> 48 TR1800 65 Morgan 4/4 Series V
> 71 Saab Sonett III 75 Bricklin SV1 77 Spitfire
>
>
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