BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Gibbs on 23 Aug, 2026, 11:27

Title: M21 gearbox
Post by: Gibbs on 23 Aug, 2026, 11:27
Hi,
 I am finally getting some great miles under my belt on my 1947 M21. I've had to do a complete gear box rebuild using another box to mix and match. Getting into gear and changing down are a bit of a mission and I can't help thinking that I've done a bad job on the rebuild. Does anyone know of someone who could look at the gearbox and clutch and sort out my mistakes? I live in Northern Ireland and would have to send the offending parts in the post.
Rob Gibbs
Title: Re: M21 gearbox
Post by: Jim S on 23 Aug, 2026, 15:21
Before you remove the gearbox, have you checked that the clutch isn't dragging when it is disengaged? A dragging clutch can cause shifting problems.

Jim
Title: Re: M21 gearbox
Post by: limeyrob on 23 Aug, 2026, 17:44
I'm thinking the same, make sure the clutch is right before digging into the box.
Title: Re: M21 gearbox
Post by: Gibbs on 10 Oct, 2026, 10:29
Thank you chaps! That's the plan, parts can be tricky?