This is the large oil retaining shim that is fitted between the mainshaft sleevegear and main gearbox bearing on all upright and laydown Norton gearboxs from the 1930's to late 1950's (i.e. pre-AMC) - as per original fitment. Price Is Each
This shim is shown in both the pre-war (part no 9665) and postwar (part no A2/317) Norton Spare Parts Catalog, and is unusual in that the original shim outer diameter was so wide, it virtually covered the gear teeth of the sleevegear. I believe the intention of this shim was to prevent the loss of oil through the main gearbox bearing - which was normally unshielded.
Although original Norton sleevegear's had a very slight lip at the extremity of the shoulder (so that the teeth were inset from the outer bearing ring) - invariably the original shims rub against the teeth and main bearing outer race and wear away. Therefore, it is most normal to find when stripping down an old Norton gearbox that this shim has been omitted, or is present and started to break up with heavy wear.
These shims have been replicated from good quality shim steel from an original Norton pattern (which had all the signs of wear described above!).
Additional Background Information Feb 2020:
I have been asked on multiple occasions by customers over the years if I can supply this original type shim, so am pleased to now be able to offer it. If you have an original style gearbox main bearing - which were unshielded, then this is probably still the best way to ensure excess gearbox oil does not leak over your garage floor!
However, in modern times - it is not unusual for Norton gearbox's to have main bearings fitted with either modern sealed bearings (i.e. a nylon ring encasing the ball cage), or a shielded bearing - of the type we sell for the Norton gearbox (Item 0029). Like most longterm Norton owners - I have questioned the validity of using this large shielded shim, if using a caged bearing - which itself goes some way to prevent excess oil escaping . . . but I cannot recommend either way, I think it is personal choice - but it was always fitted by Norton's themselves as far as I can tell until the mid 1950's.
If like most people you want to fit the original fitment shim - then this is the correct dimensions and type. However, we do also offer Item 0854, which is based on the shim used on pre-war gearbox's on the other side of the bearing - which has a reduced outside diameter. If you just want the correct thickness shim between sleevegear and bearing - but do not want to fully cutoff the supply of gearbox oil to the main gearbox bearing - then you may want to consider using Item 0854 instead . . . I will leave that to you, I am not too fussed which one I use on my own gearbox's!
It is important to note though - if not fitting any shim at all in this position, it may result in their being excess play on the mainshaft - so it seems prudent to fit one of them.