Author Topic: 1949 B31 Gearbox  (Read 336 times)

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Andmaxjar

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1949 B31 Gearbox
« on: 20 April, 2017, 14:16:27 »
Hi All,
Have started to rebuild a gearbox for a 1949 B31 and have found when I pulled the box apart there did not appear to a sprocket oil seal that is shown in the parts book.
I purchased all the bits I needed from Draganfly but when I started the reassembly it did not seem that there was enough room for the bearing and seal.
So I just put the bearing in as before, tapped in the sleeve gear, placed the sprocket on and fitted the retaining nut and found that the nut only just covered the threads which is fine.
If I tried to fit the bearing seal this would cause the bearing to sit further into the box moving the sleeve gear in as well causing the amount of threads for the nut to retain the sprocket to be minimal.

So after all of that my question is did this type of gearbox not have the oil seal even though it is shown in parts book.
By the way I used a bearing with seals so oil leaks should not be a problem.
This is my first BSA single so a bit of a learning curve.
Cheers
Andy

JulianS

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Re: 1949 B31 Gearbox
« Reply #1 on: 20 April, 2017, 15:35:34 »
The parts illustration used by Draganfly looks like it is from the 1949-53 parts book.

That book does not give all the information for the earlier models.

I have checked the 1949 and 1950 parts books, which were issued at the time and which covered all models in the range.

The gearbox page notes that the oil seal, part 65 3508, was fitted on and after frame number ZB31 7840 for rigid frame and on and after ZB31S 6032 for plunger frame, which puts the change sometime during the 1949 or 1950 season, boxes without the oil seal would have sprockets with an oil scroll.
« Last Edit: 20 April, 2017, 15:45:44 by JulianS »

JulianS

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Re: 1949 B31 Gearbox
« Reply #2 on: 20 April, 2017, 17:00:58 »
This is the page from 1950 parts book.

Andmaxjar

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Re: 1949 B31 Gearbox
« Reply #3 on: 20 April, 2017, 22:33:31 »
Hi Julian
Thanks very much for your reply, the engine I have is an early number #173.
So that explains why everything lines up and would not if I fitted the seal, one less thing to worry about.
Cheers
Andy