I don't have a speedometer on any bike I own, (except the Army bike, and it don't work). This '54 I'm building has original H-D tanks, original H-D dash - and it seemed a shame to use a Chinese speedo, so I found an
H-D Stewart Warner Police Speedometer (at a decent price, 'cause I'm kinda cheap).
Now here's the shitter . . .
Upon research, I found I had the wrong speedo worm gear pressed on my cluster gear for the correct 1:1 ratio for this speedometer. I had a 7 tooth, and needed a 4 tooth . . .
I had the transmission all done and assembled. Shit. I had to strip it all down, and remove the countershaft and press off the old gear, and press on the correct gear - then we indicated the gear by placing the countershaft upright on-end . . . on a machined/precision parallel bar. The speedo gear face was corrected (to minimal run-out) by lightly pressing and tapping at the high spots. It runs true now. The correct 13T drive unit was installed and tested. It runs nice, quiet and true. This will extend the life of your gears, and possibly the speedo itself by allowing the cable to turn free with minimum vibration.
Now when I get hassled by The Man ......
they'll just get me for No Mufflers.
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1937-1980 Big Twin 4 Speed Transmissions
1937-1961 = 11T Trans Gear 7T Speedo Drive
(for 2:1 speedo with internal female threads)
1962-1969 = 4T Trans Gear 13T Speedo Drive (1:1 speedo male threads)
1969-1980 = 7T Trans Gear(fine tooth) 23T Speedo Drive(fine tooth)
(1:1 speedo male threads)
I believe all front wheel drive speedometers are 2:1 (corrections always welcome !)