Well, now that you mention it:
I ahve found out that you CAN recalibrate a speedo in a limitied
fashion. I did it when I made one good one out of two bad ones by
swapping parts around in a couple of 1280 rpm speedos. One of them had
a bad odometer, the other had a bad speedo. Anyhoo I mated up the good
parts but the speedo read ~10% high. On my units, the speedo needle is
a press fit on the shaft coming out of the rotating drum and the drum
can be rotated by hand, form the side, when the instrument is out of the
case. There is a clock spring behind the instrument's face that
provides tension for the drum to rotate against. The spring tension
increases as the speed reading increases. The drum on mine has a dab
of black ink on its edge that shows from the side when the needle is at
0. I found that I could fine tune the reading by removing the needle
while holding the drum stationary, then rotating the drum a bit and
reinstalling the needle. More tension to lower the reading and
vice-versa. It was strictly trial and error - change the tension,
reinstall it, go drive it, etc. - and I had to tweak it several times
but it reads correctly now.
This is just for info. I'll take no responsibility if you break it
trying this but it worked for me.
Charley Robinson
'69 B
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