B31 rigid rear wheel hub sourcing

[KiwiGF]

Hi, I've got a B31 rigid project but no correct rear wheel. Just a plunger one.  Ive been looking for a while but thought I'd ask here for advice. In one of the pics is a rusty hub seen on ebay and said to be m20 or b31 but its pricy and in the uk and probably has a worn sprocket anyway, there are 2 pics of a hub that came with the project, but it has different size spoke flanges to the ebay hub.

 So my first question is can anyone identify the hub I have? (With different size flanges).

Second question, can anyone suggest a way to make up a wheel starting from a bare hub without the drum and sprocket riveted on?

The rigid wheels are type 9 on the draganfly site and are an odd design as the sprocket is riveted to the hub making replacement of the sprocket difficult, I'vd heard of worn sprockets being machined off in situ and a new sprocket ring welded on.

[bikermike]

did you ever get a reply ? as i have a wheel for my project deep in my garage if you need it sizeing mike

[KiwiGF]

hi mike, no answers but then this an a7/10 forum!

Things have moved on, I found someone who had a large stock of old parts and after hunting through ariel and triumph stuff I came with e a complete wheel and brake with different size spoke flanges (larger flange is on the drive side, smaller on non drive side), which now Ive got it home I am increasingly convinced is either from the bsa b20/21/23/24/25 range or another brand of bike. Would be great if anyone could confirm what it is.

But the good news is I also picked a hub that looks like a b31 rigid hub eg 2 spoke flanges the same size, as picured in my earlier post, and it has a riveted on brake hub, but it has slots for a rear wheel speedo drive which is odd for a b31 age bike, and it needs a new sprocket and bearing housing repair, obviously also rims and spokes.

if you have a pic or sizes of a b31 hub that would set my mind at rest that I have found the right one.

Ive given the hub with same size spoke flanges o a local engineer to fix up but would like to hear from anyone who has fitted a new sprocket teeth to the riveted on hub? He has done it before but was undecided on whether to try to use small screws to fit a slightly larger sprocket on, 44 teeth versus the std 42, or weld a 42 tooth on and risk distorting the drum.

Ive heard some people perfrom a similar repair to crinkle hub wheels S fitted to a plunger a10 even though new drums/sprockets are available for those?



The b20 wheels and hubs, pictured below, and if thats what they are, I will try to find a home for in due course.....

[Brian]

I dont know if this will be much help but here are a few photos of the rear wheel in my rigid B31 (1947 XB31).

I made the axles and nuts etc myself plus did a modification to the frame to get rid of the snail cam adjusters.

[bikermike]

hi, i see we have input from Brian with nice pictures thank you , Brian's wheels look the same as mine my bike a zb .right i don't pretend to know what i am on about for a start but here is my input the equal sided wheel you have sounds like a earlier model ie no gearbox speedo drive ,the earliest bsa i have with girders drives on the front wheel. now if the wheel you have is exactly the same size as the b31 one that needs work can you not press the spoke side plate off and swap them over ? is seem to remember there is a sprung ring it sits on. maybe make a small cover over the speedo cut outs. hope this makes sense mike         

[KiwiGF]

Thanks Brain and Bikermike, this really helps, it looks like I can refurb the wheel with different size spoke flanges and fit that, I'd better go and tell the engineer pronto!

I have the axle and bearings for that wheel, but it still needs a new sprocket,

Couple of more questions tho!

Is the rear drum a 7 inch? Is so what width is it ? (I ask as the 2 drums I have are slightly different width).

The bearings are smaller outside diameter on the wheel with different size flanges, I'm told some wheel bearings are "unobtainium" so my question is, is it the smaller type or larger type bearing that are impossible to get. Or both!

By the way the usual source of info on this sort of topic Draganfly only show the one rear wheel, not both types that appear to be found on b31s, so Im going to have to careful I get the right spokes and bearings when I order them. The spokes Draganfly list are different lengths which one would expect if the spoke flanges are different diameter.

[bikermike]

hi, i hope i have not miss lead you but i think there is just one true rigid b31 rear wheel that is as Brian has shown ie the big and small flange type. but saying that the early rigid  frame had quite a few differences mine is the late zb type . yes i do know the brake is 7 inch i will have to get to the back of my shed to get you the width and bearing size,so may be a day or two. i do recall the bearing were hard to get at one time but i seem to remember a alternative was found . please don't take all  i say as gospel im no expert . mike

[Brian]

The original set up has tapered roller bearings. When I did mine they were available but at a horrible cost so I modified my hub to take modern metric ball bearings and made a new axle etc. Mine was well and truly mangled so I had to make new everything anyway so decide to do the modification. I also changed from the original snail cam adjusters to the bolt type, so far no one has noticed.

[orabanda]

Brian,
I noticed!!!
Richard

[duTch]

  Not the clearest, photo from computer screen- may be a bit hard to read, but any help...?

   From original parts book,ust says B31 '49-'53 Rigid

  Cheers

[Brian]

Richard, that would be right, there always has to be someone 

Actually its a good little modification as it makes the rear wheel a lot easier to adjust and align correctly.

And yes I know its not original but hardly any of my bikes are. So shoot me 

[orabanda]

Brian,
It's OK; our little secret!

[KiwiGF]

thanks everyone, yes dutch that helped but if only bsa had shown both spoke flanges not just the non drive side I would have not been in this quandary!

 I'm going with the hub that has the different size spoke flanges, I'm not sure on how the sprocket will get renewed though, any experience of doing this anyone so I can give the engineeer some tips on how to do it?

By the way draganfly have the taper bearings listed at 27gbp each, which is more than bearings usually cost but bearable (no pun intended). If they dont have them in stock I will get the hub converted to ball races.

Im a bit tempted to do the chain adjuster mod as well as otherwise I would have to repair the frame as the pins which work with the snail cams have been ground off by a PO.

[Brian]

If you do decide to do a ball bearing conversion here are a few more pics that might help.

I used metric bearings and machined the hub to accept them. It was few years ago now and I cant remember exactly what size they were. I think they had a 12mm inner dia. The nuts have a inner boss to locate in the frame so the slightly smaller dia didnt matter, the original is 1/2" (12.7mm).

If you look carefully you will see I made the nuts that screw up against the bearings with a flat surface with two holes in them, I then made a tool with two prongs that located in the holes to tighten them up. If you retained the snail cam adjusters you would need a different set up. If you do modify the adjusters as I did you need to make the outer nuts with wider surfaces so the adjuster bolts push against them.

Rebanding a sprocket is not all that difficult and your machine shop should be able to do that . They will machine off the old one and weld a new band on and then machine the drum as welding on the new sprocket distorts it.

If your existing axle etc is all in reasonable condition 27 quid each for the new bearings will be the cheapest option.

[bikermike]

well if nothing else i got you some in put . been to the back of the shed dragged my wheel out removed spindle only to find my vernier battery flat so this is approx but will satisfy you yours is correct . tube part of hub internal diameter approx 41 mm. spindle 1/2 inch. tapered bearing ,number timken OCC8OX, the first c has a dot above it  also its a eight not a b and lastly i think that's a x on the end .  now brake drum ,riveted on with 8 rivets over all width 35 mm . from out side to out side of sprocket 30 mm , any help ? mike