How do you identify the correct speedo , ive got the early underslung cowling and road rocket headlamps , some speedo have the bolts for fixing , one has none , there also seems a 8 inch cable to reset the trip , are the part numbers stamped on the smiths
instruments anywhere , phil.
Mod edit: title edited. Please always use a descriptive title in the tech boards (forum rule).
As a general rule if you get your hands on any smiths chronometric of the right size (80mm) and era (50’s and 60’s) you will be able to get it modified to look correct. I am not sure if the 80mph versions are different from 120mph so it might be best to look for 120mph unless someone else on here knows about this. You could spend a long time finding the “correct” speedo, and then find out the dial has been replaced and the internals are not correct anyway.
New dials can be printed with any part number nowadays, if you want to go to the lengths of getting that right.
ODO resets can be on the side or bottom, in NZ it’s not easy to get a conversion done to side reset as the additional internal parts needed are hard to get (or at least they were when I last tried to get it done).
For a cowl mounted speedo where the speedo is mounted in rubber you need the type of bezel with a flange, speedos (rear) bolted on have bezels without the flange as they need to look nicer. Both types of bezel are being reproduced nowadays.
Needles, the other part needed to look correct, are being reproduced.
The internals can easily be adjusted such that the speedo reads speed accurately, getting the ODO to read accurately is not so easy, others may know more about that.
Chronometrics are not cheap, and neither is their restoration. A good restorer should be able to take pretty much any chronometric and give you back a restored speedo of the correct spec, reading speed and distance accurately, you may not get back the same speedo you gave them though.
For my B31 speedo, which was battered but appeared to work ok, I bought a needle, glass, rubber seal and bezel from the UK, and fitted them myself. It looks the part (but has the wrong part number on the dial), but over reads speed and distance by 20% but that doesn’t bother me.
For my A10 the speedo did not work and was missing dial and needle, and I gave it to a restorer who gave me back an immaculate speedo which worked and is accurate for speed and distance, it doesn’t have the right part number on the dial though.
Just my 2 cents worth!
