Author Topic: B 31,33 gearboxes  (Read 209 times)

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MGI

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B 31,33 gearboxes
« on: 13 January, 2020, 17:16:19 »
I am aware of the year of my frame and I am aware of the year of my engine (vastly different) but I am curious as to if the year of my gearbox can be identified, I know that the shape of the gear box, or possibly only the lugs changed when the swinging arm frame came about, Is it the fact that since the inception of the SA frame. circa 54/5 all the subsequent gearboxes were interchangeable? Do they have numbers stamped on them somewhere to allow dating?

Thanking you in anticiation..

JulianS

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Re: B 31,33 gearboxes
« Reply #1 on: 13 January, 2020, 17:31:48 »
All the swinging arm B31 B33 A7 and A10 and Gold Star gearboxes interchange in swinging arm frames. The earlier boxes dont fit these frames.

The first were introduced in late 1952 when the swinging frame was introduced for the 1953 season Gold Star models.

There are no dating codes on the boxes.

You dont say what year or suspension your bike has.
« Last Edit: 13 January, 2020, 17:47:18 by JulianS »

MGI

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Re: B 31,33 gearboxes
« Reply #2 on: 14 January, 2020, 16:40:27 »
The frame is 1958, the engine is 1947 and the suspension is swinging arm. It has the larger single sided front brake and it does not possess a full size front hub. It has a  magdyno which  is retarded by pulling the lever backwards. It appears to be a real 'bitsa'! Other than the foregoing is seems to be a nice example, bearing a passing resemblance to a RGS.

JulianS

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Re: B 31,33 gearboxes
« Reply #3 on: 14 January, 2020, 17:54:47 »
Your front brake is probably the best of the BSA single leading shoe brakes, much better than the 7 inch full width hub used for 1958 models.

MGI

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Re: B 31,33 gearboxes
« Reply #4 on: 15 January, 2020, 15:12:09 »
I also possess a 1956 B31 which has the full width Aeriel hubs and a single leading shoe front brake. This brake appears to be singularly ineffective. I do have a TLS wheel/brake assembly which looks identical to the unit fitted to some Triumphs and BSAs around 1960. Does anyone know if it possible to retro fit such a unit to my B33, either by changing the lower fork legs and shrouds or failing that, the entire front fork assembly?