Barney,
I picked up a serviceable speedometer at a swap meet this weekend. My
C/GT speedometer has 980 on the face and this new one has, maybe 1230.
The C is supposd to have 3.7 gears (or 3.3) and mine has a 3.9. On a
road test the odomoeter is (surprise!) pretty darn close enough.
But the speedometer is 20% high. (At around 60 I'm seeing 70+).
So you wanna take a guess at how much material should be taken off the
end of the permanent magnet to bring the speed down 15-20%? Or at least
a good rule of thumb? Increase the air gap to the outer flange 15%? Or
should it be 7.5%?
The speedo was cheap; this is just a curiosity experiement.
Bob Allen, Kansas City, '69CGT, '75TR6
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