Hi all...I am restoring a 1941 m20 that has a three speed gear box. The gear box looks exactly like the JHL four speed box. I fairly sure that the m20's where not produced with a three speed box. Does anyone know the history of the BSA three speed gearbox?

Bryce,
Does the inspection cover say it is a three speed, as that may be a cover off the earlier three speed box.

Hi Bryce...It is most likely that you have a 3 speed gearbox plate fitted as Darren suggests. The WD M20 was never fitted with a 3 speed box.

If the box has a gear indicator plate fitted where the gear lever fits that will be marked correctly (1234) for a 4 speed box...Ian

email (option): ian@wright52.plus.com

It has no gear change indicator plate, but you could be right that its a three speed plate on a four speed box. Only one way to find out, I will take off the inspection cover. Thanks four the replys.