Norton numbering system

I have just searched the website in vain for this as I had a hunch it was in the History section.  I want to date a couple of 'dolls head' gearboxes I have and hoped to find numbers and dates listed.  I have Bruce Main Smith's "Norton Motorcycles 1928-1955" and Roy Bacon's "Norton Singles", both of which give details of the system of year letters and engine and frame numbers relating to years, but nothing on gearboxes.  It would be very helpful to have all this info' on the website to help with dating 'basket case' and incomplete bike parts.

Andy Mullins

Unfortunately, the stamped boxes were not assembled into complete machines in any particular order and were often hundreds or even thousands out of sequence. The club should be able to advise on particular boxes from the factory records database. Searching for them in the ledgers 'manually' is very time consuming.

It goes without saying that the vast majority of Dolls Head boxes were originally fitted (or supplied as spares) to WD machines and few of those factory ledgers have survived.

The drain plug doesn't seem to have made its appearance until wartime production, as did the brass gear position indicator so although the cover can be changed, that is an indication of WD origins (or else the limited post-war use such as 500Ts)

Just to give an idea, Gearboxes were being numbered in the high 5000s during July 1935 and had reached 29000 odd by October 1939 (although I see one on the page that is 26000 odd). By November 1940 which is when the last WD build book ends, gearbox numbers had reached just over 52000. Anything higher will probably be WD and can perhaps be guesstimated by calculating WD 16H and Big 4 production.