Speedometer identification

I purchased an ex New Zealand police '71 Commando in the mid '70s fitted with a cronometric, and later purchased a 650SS also ex NZ police fitted with a cronometric, apparently the cronometric's were more accurate than the later magnetics'.

It looks like the Singapore Police turn their bikes in when they reach 20,000 miles?

Norton changed from the Smith's chronometric instruments to the magnetic type I think from 1964. The Mercury would have had a SSM3001/00 and used a rear gearbox drive with ref BG.5330/257, which  is a 2:1 ratio(same as 650SS/99

Should be  similar to the picture attached of the one fitted to my ‘68 Atlas

 cheers Simon

Yes but as I have stated previously Bikes that were supplied for police use here in New Zealand at least were supplied with cronometric speedo's, I would be interested to know what was fitted to Interpols? cronometrics as are more accurate. 

Not keen on the word 'ugly'! It's the 'classic' chronometric as fitted to countless British bikes for well over 30 years, except yours is an export model without the white bar marked at 30mph which they have in UK.

Commando Interpols had the econometric speedos fitted, parts book confirms.

I've just realised!  That's the famous large one as used on Vincents (and, presumably, the police)!  You could probably buy a new  motorbikes (maybe not a Norton) for the second hand value of that.  It's near enough a mythical beast - I'd keep it or sell it - I certainly wouldn't take it off and stick it on a shelf somewhere.

There is one on Ebay right now at £1200.  (not yet sold...!)  Although the Vincent one is 150mph, so maybe yours is not that good, sadly.

The speedo on my -68 650SS is a grey face 190km/h SSM5001/01A. Could be same on a Mercury. I think it's nothing wrong with your speedo if fitted on a better looking plate. That 5" speedo would look nice on my Vincent Comet, making  it look a bit more like it's black big brothers.

if you aren’t too worried about originality and assuming you are keeping the Mercury to standard road spec there are modern electronic versions of the grey faced Speedos available. A quick Google or Ebay search should find one. 

Hi Terry,

   Your speedo looks quite old, probably 1940s or '50s, and if it is 5" diameter with the mid speeds at the top of the dial, I would guess this is from a car such as a Jaguar or sports car. I don't know how this would work though as most car speedo's run from the gearbox and the calibrations will be completely different.

Sorry I did not note it was 5" the ones I have seen have been std size.