The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: RoadRunner on 21.02. 2011 21:55

Title: Plunger Gearbox differences?
Post by: RoadRunner on 21.02. 2011 21:55

Hi,
A question has arisen more out of my curiosity than a problem; I've got two gearboxes for A7/10 Plungers and I've noticed a difference on the RHS. The g/box used on my bike doesn't have a grease nipple (28-2080) beneath the clutch operating lever neither does it have Kickstarter spring screw locknut (27-4401) near the rear of the box. The spare g/box has both of these features as illustrated in the BSA spares manual.
Is one an earlier version or off a different model and if so what is what? Presumably the internals are the same??
Any thoughts would be appreciated?? Just interested really - serves me right for getting a spare box!

Cheers
RoadRunner

Title: Re: Plunger Gearbox differences?
Post by: trevinoz on 21.02. 2011 22:25

Early boxes have no grease nipple and have a flat section clock spring for the kick start return.
Trev.

Title: Re: Plunger Gearbox differences?
Post by: RoadRunner on 21.02. 2011 22:35

Thanks Trev,

Thought it might something like that (well hoping) - the later g/box with grease nipple arrived with a set of early A7 longstroke cases (know that doesn't mean much), and the earlier g/box is on my '55 bike!

Any idea what date the improvements were made?

Cheers
RoadRunner

Title: Re: Plunger Gearbox differences?
Post by: bikerjohndavies on 22.02. 2011 08:09

Hi Roadrunner, Slightly off track but what happened to the long stroke cases ?

Cheers, John

Title: Re: Plunger Gearbox differences?
Post by: RoadRunner on 22.02. 2011 08:35

Hi John,

Nothings happened to them - they're just sitting here. My BSA has a A10 GF plunger '55 frame and A10 cases but with A7 top end. Was thinking of swapping cases at some point so the engine number actually matched the top end. But as you know the early cases are different regards the internals so cannot swap without buying more bits (a lot more bits)!

Oh, and I've a reground crank plus new bush and shells to go with it.

Why?? ;)

Cheers

RoadRunner

Title: Re: Plunger Gearbox differences?
Post by: trevinoz on 22.02. 2011 20:21

RR,
         I am thinking 1953 for the modifications. There was also a seal fitted to the output sprocket instead of the tin shroud.
              Trev.

Title: Re: Plunger Gearbox differences?
Post by: RoadRunner on 23.02. 2011 09:42

Thanks Trev,

As long as the g/box without the mods works and doesn't look out of place that'll do me!

This is a real journey of discovery about BSA A7/10s - won't to buy any other bike now due to gaining such knowledge and tools; but that can't be bad......

Thanks again for putting my mind at rest. ;)

Cheers
RR