I agree with getting a second opinion about the speedo calibration,
but as a old-time rallyist I wouldn't trust anything other than a
stopwatch and a measured mile.
My favorite method is to find a fresh stretch of highway. One that
hasn't been torn up too much, because they tend to rearrange the
mileage markers when they do construction.
Motor along at exactly 60 mph which translates to one minute per mile.
Measure the time. If it takes you 66 seconds to travel one mile
(which ideally should be traversed in 60 seconds) then calculate
66/60 x 100 = 110% (as an example).
Try this at several different mileposts to get an average because,
as I said, the highway dept (and intoxicated drivers) move the markers
around a bit.
For the best accuracy I prefer to visit the local cop shop and ask
where THEY calibrate the police car speedos.
They usually have a measured mile somewhere in town. The only
downside is that they often start to ask you a lot of questions.
They think you want to organize drag racing there or something, and
if you let slip that you have a "sports car" you're in for it.
Tell them you're training for the Olympics (although with my frame
that's a stretch).
If the measured mile is in town and you can't do 60 mph conveniently,
the factor for 30 mph is 120 seconds per mile, and for 45 mph it's
90 seconds.
Happy Motoring
Joe DeLuca
Sparta, NJ
'62 yellow 4/4
-----Original Message-----
From: John T. Blair [mailto:jblair@exis.net]
Sent: Monday, July 20, 1998 5:23 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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