[Healeys] Speedometer gearing

Per Schoerner healeyguy at bredband.net
Sun May 15 14:25:54 MDT 2011


Hi
I'm trying to figure out the speedometer drive gearing inside the 
different gearboxes. I'm helping a friend with his speedometer. He has a 
100-6 which was delivered without overdrive. My own car is a 3000 mk2 
with overdrive. The rear axle gear ratio on these cars are the same, as 
far as I understand, according to Clausagers book. But the speedometers 
are different. The 3000 speedometer needs 980 revolutions per minute to 
show 60 (MPH) and advance the odometer 1 mile in one minute. The 100-6 
speedometer needs 1575 revolutions per minute to do the same thing. Note 
that both cars are imported from the states, so both are speedos are in 
miles.
Does anyone know what the difference is? Well, I can calculate it of 
course, but I thought asking on the list would be safe in case I have 
got something wrong.

Best regards, Per from Sweden.


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