Author Topic: B31 rigid rear wheel hub sourcing  (Read 7233 times)

Online KiwiGF

  • Last had an A10 in 1976, in 2011 it was time for my 2nd one. It was the project from HELL (but I learned a lot....)
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Re: B31 rigid rear wheel hub sourcing
« Reply #15 on: 20.01. 2014 09:26 »
thanks bikermike, that info has absolutely convinced me I was lucky enough to buy the right wheel for the b31, my sprocket has 40 teeth but is dimensionally the same as yours.

Thanks Brian very much for those pics, I will print them out and show them to my engineer guy, I have a lathe (pre war southbend) but I cannot get the accuracy to make those parts myself.

Once I get the wheel done can get on with the rest of the bike, it did look at one stage I was going to have to adapt a plunger wheel to fit!

I'm really glad I asked for help on this forum, as far as I know there is no forum for the b31/33 range, Ive done quite a bit of searching but not found a specialist forum for the pre unit bsa singles.
New Zealand

1956 A10 Golden Flash  (1st finished project)
1949 B31 rigid “400cc”  (2nd finished project)
1968 B44 Victor Special (3rd finished project)
2001 GL1800 Goldwing, well, the wife likes it
2009 KTM 990 Adventure, cos it’s 100% nuts

Offline terryk

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Re: B31 rigid rear wheel hub sourcing
« Reply #16 on: 23.01. 2014 13:42 »
Keep asking B31/33 questions here on this forum there are many members that have extensive knowledge about them and are only to willing to help. There is no B31 website forum you can also ask question on the M20 website lots of help there as well.
1950-53 A10 rigid/plungers, 1958-61 A10 super rockets, 1947-50 A7 longstrokes, 1949 Star twin,
1951-54 A7 plungers, 1940s M21, WDM20s,
1948-50s B33s rigid/plunger/swingarm, 1948-50s b31s rigid/plunger/swingarm

Offline smellybeard

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Re: B31 rigid rear wheel hub sourcing
« Reply #17 on: 23.07. 2024 16:31 »
I'm planning this job at the moment.
Somewhere in the shed, I think a spare worn out drum/sprocket is hiding. My plan was to tackle it first and then the rest of the wheel.

To anyone who's done this job, is removing and re-riveting the drum-sprocket to the hub practicable without re-spoking the wheel?
Am I looking at basically building a new wheel?

Online limeyrob

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Re: B31 rigid rear wheel hub sourcing
« Reply #18 on: 23.07. 2024 18:17 »
A coupe of points:
Nails are very close in steel grade to solid steel rivets so it you can find the same size nails (dia) they make very good rivets.  I used this method to re-rivet a clutch basket to the sprocket and it worked very well.
Be careful with the rear sprockets on a B31, some ar only 1/4" wide, they vary by year.  If you can get the whole front/rear/chain set off a B33 or A10 as the 1/4 wide chain is undersized.
Yes I think you could do it with the wheel assembled, but building a wheel is not hard so be prepared to take it apart if its getting in the way.
Slough 59 GF/SR