Smiths Chronometric speedometer numbers

[Greybeard]

Hello, folks.
Does anyone know what the final part of the model number signifies? Not an AMC question I know but there is a huge fund of knowledge here.
Im restoring a Panther M120 which needs a SC3303/17 (calibration number around 1650). Ive seen one that has a /35 number. What's the difference ? Hopefully it'll be something insignificant like the shade of red used for the 1/10th mile digit
The bike came with an inoperative 150mph jobbie - SC3303/01 (cal 1550). Even a mighty Cleckheaton 650 sloper may struggle to use any more than half the dial. I've no idea what it may have come from.

Steve

[39speedtwin]

SC3303/17 relates to a 1960 Panther 100, also 50 Sports Twin.
The important bit is the 1650, this is cable turns per mile and is derived from the gearbox which should be BG 2517/00.
The SC 3303/01 was fitted to Royal Enfield Bullet to Constellation 1961.
Again what the /17 /00 etc mean I don't know.

[Greybeard]

Thanks for that. Interesting that the 150mph one is an RE job. Ive just sorted an Albion g/box problem on a mate's 750 Interceptor.

Steve

[Pharisee]

Give Russell at Chronometric Instrument Sevices a ring (01159 206156) ... He's a ex-Smiths Instruments engineer and knows a whole heap about speedos and rev counters.

[Greybeard]

Will do. I did try today but could get no answer - mebbe on hols ill try again but thought I'd ask here first as the auction ends on sunday


Thanks. Steve

[clive]

If you find out please post here. I used to fix smiths speedos and despite looking at much of their paperwork i never was able to figure out the numbering system.

[Greybeard]

I will, Clive. It all seems to be closely guarded secret so far

Steve

[39speedtwin]

Steve,
As you have the 150mph Chronometric, have it repaired to the specification for the Panther.
Be very wary of those on Auction websites, I have seen some horrors, missing critical parts from the clockwork!
You can always PM me.
Dudley

[Greybeard]

PM on its way, Dudley.

Regards. Steve

[39speedtwin]

I have asked regarding the numbers and will post the reply.