The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: ADP91 on 14.06. 2015 21:27

Title: Gearbox differences
Post by: ADP91 on 14.06. 2015 21:27

Hi all,

quick question about the differences between a10 gearboxes. I am aware that the rigid and plunger gearboxes mounts directly to the rear of the engine but I'm wondering if the actual casings are different between plunger and swingarm models. I have a '59 engine and bought a gearbox that has STD and 42-3006 stamped on it.

Can anyone tell me if this model of gearbox is an older plunger model or a swingarm model? is there a difference?

cheers, A

Title: Re: Gearbox differences
Post by: beezermacc on 14.06. 2015 21:42

The casings are completely different. The plunger box has a big square casting at the front with a hole in each corner for the mounting bolts to the engine. The swinging arm box has lugs top and bottom for the main mounting bolts to slide through. The outer and inner covers are also slightly different due to the different gear lever return mechanism.

Title: Re: Gearbox differences
Post by: duTch on 15.06. 2015 13:59

 In addition to what Beezermacc said, the 'STD' just means 'Standard Ratio' gears and according to the parts list, it's a swing arm box so will go with that engine

Title: Re: Gearbox differences
Post by: ADP91 on 16.06. 2015 02:33

Fantastic, thanks for the information.

-A