A fellow has asked on another site( Britbike forum)if pre-war handchange box had a shorter mainshaft than positive stop boxes? By 3/4 inch.I presume handchange didn't have positive stop?

Hi Douglas...I'm not sure about this one. However, the kickstart ratchet assembly is on the end of the mainshaft in the WDM20 box so the length of the shaft is unrelated to the positive stop mechanism. That is connected directly to the gear selector quadrant by the adjustable tie rod.. On hand change boxes the selector quadrant shaft protrudes through the outer casing, which is narrower at that point, and the hand gearchange operating shaft connects directly to it.
So I would think the mainshaft is the same length on that end unless the ratchet arrangements differ...but don't quote me!...Ian

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

I have a 1934 BSA with the "external" foot change and it has a shorter main shaft - on the clutch side.

The 39 BSA spares list shows part number number 15-4260 for M20 std, M20 DL, M21 DL, M22, M23 & M24 but it doesn't mention any difference for hand change.

email (option): robmiller11@yahoo.co.uk

Hi Michel, The 34 BSA predates the M20 by 2 years so will have a different box altogether, much as the WB30 with its B Series box differs from the M20.....this too has a shorter mainshaft. ...Ian

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