[Healeys] Speedometer gearing

[Per Schoerner]

Hi again
I guess what I'm trying to say is that there is a difference in the gear 
ratio of the speedometer drive (the thing on the gearbox output shaft 
that drives the speedometer cable) on cars with overdrive versus cars 
without overdrive.

Per from Sweden

John Vrugtman skrev 2011-05-16 01:17:
> If you will check the parts manual, it will show a rear end ratio of
> 3.545 for non overdrive cars and 3.90 for those fitted with overdrive.
>
> John
> 64/66 BJ8s
>
> On 5/15/2011 4:25 PM, Per Schoerner wrote:
>> 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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