BSA B31 Gearbox Gearshift Problem Part 1

Been having an intermittent gear shift problem with the B31 so it's time to strip the gearbox and have a look if there's anything obvious.

[@retromechanicalengineer]

Interesting job Ian. Looking forward to the next installment. Best wishes, Dean.

[@a65builder67]

hi Ian the joys of motor biking, please could you tell me the year of the b31 the reason I ask is that I'm having the same kind of thing go on with an a10 a friend dropped off at my garage. I have not opened the gearbox yet but hoping the inner's might be the same? kind regards Adrian.

[@InTheShedUK]

Hi Adrian, the engine is 1955 and the frame is 1957, gearbox is either 55 or 57.

[@Cobra427Veight]

Would shimming between those two gears reduce the amount of dog engagement ? Wouldnt the shim be be better on the other side of the gear to the outer case or shim the outer bush in a bit ? Im not any sort of guru on british gearboxes , but some of these gears can be expensive, i think there is a video of a norton box on Utube with a similar issue , i hope you get it sorted ive found extra neutrals on my B33 to 🤔 . Cheers .

[@InTheShedUK]

Yes, some experimentation definitely required!

[@a65builder67]

hi Ian thanks for your reply, the a10 is a 53 so may or may not be the same I beleave some have adjusters on the gear change quadrant we'll after see anyway thanks again Ian take care.

[@InTheShedUK]

Yes, probably different gearbox, 53 will be rigid or plunger frame. I think they went to swingarm in 1954.

[@a65builder67]

hi Ian yes its a plunger@@InTheShedUK