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Smiths mechanical govenor speedometers
#1
I know information is rather scarce on these but does anyone know if they made a PN 100 mph version ?
This is the one with the 45 degree drive as fitted to Ulsters,earlier Chummies etc
The reason I ask is I have just bought one but suspect it might just be a clapped 60 fitted with a new 100 face.
Any advise please
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#2
As a supplementary question, is it possible to recalibrate these. I have a good PA @ 2240 turns per mile, which I’d much rather worked at 3360.
Alan Fairless
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#3
Is that for a belt driven speedo drive,I think they are an A and not too uncommon.
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#4
Yes it is.
Alan Fairless
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#5
(27-01-2019, 11:00 PM)Alan Wrote: As a supplementary question, is it possible to recalibrate these. I have a good PA @ 2240 turns per mile, which I’d much rather worked at 3360.

I think a TN is pretty close to that, they seems to come up regularly.
Cheers

Mark
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#6
The standard reply to the question of changing the range of a governor speedo is "make a gearbox".

Which, I am sure, is the best solution.

On mine, I changed the spring that the weights move against, trying different springs made from whatever wire I had around.

It has worked, reasonably well, for a long time.

Simon
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#7
Thanks, Simon, but I really need the mileage to be correct as well. Speedograph Richfield will sell me a correction box for about £100. That will do the job but I’d rather have the speedo recalibrated if it’s possible. I suspect the economics might rule it out though.
Alan Fairless
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#8
How about changing the pulley sizes instead
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#9
Dave/Alan

Have you seen this?
http://www.magnetic-speedometer-repair.c...rWorks.php

It would seem that much is possible, if you're brave.

Charles
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#10
I spoke to him a year or more ago.He would only recondition not recalibrate.A recon was I believe about £250.
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