Rigid B31 rear wheel

[Reggiesdad]

I have a 1949 rigid B31. It appears to be impossible to find a new rear brake drum/sprocket for this model. They do seem to be relatively easy to find for the rear wheel in the plunger framed bike.
There is currently a B31 on ebay which appears to have the QD rear wheel out of a plunger framed bike. It makes me wonder how easy it is to fit the rear wheel of a plunger framed bike into the rigid frame.
Anybody out there tried this?
https://www.ebay.co.uk/itm/394549428302?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=zwzot_njrom&sssrc=4429486&ssuid=M7UiSpqaT6i&var=&widget_ver=artemis&media=COPY

[idie]

You may have to check spindle diameter. I was going to do this on my M33. I think the swinging arm QD hub is a better fit. The swi gi g arm hub is the same as the A10 ridgid one.

[Reggiesdad]

Thanks for your reply. My rear sprocket is still OK, but I wish they were easier to replace when worn out.

[Derek996]

I'm in the same boat with a rigid framed 1948 B32 Competition. As well as the spindle size there is the width of the frame across the wheel mount lugs and the chain alignment to take into consideration.
The rigid frame measure 6 ½" across the lugs, the plunger frame is 9 ⅞" between them and the M20 is 7 13/32". I can't see any of the QD wheels fitting into the rigid frame.

[Reggiesdad]

I know, Derek. This is what puzzles me about the rigid bike on ebay with a QD wheel fitted. How did he do it, I wonder.

[Derek996]

Perhaps he just sprung the frame to get the necessary width? But thinking more about it there are distance pieces on either side of a crinkle hub and at least one of them is fairly long, about an inch and a half if I remember correctly. What we would need to find out is the width of the hub and brake drum / sprocket assembly without the spacers. If it is less than 6 ½" then it might be possible to fit with spacers to suit although the slots in the frame would need widening to accommodate the larger diameter spindle.

[neil1964]

I have couple of bikes with crinkle hub and the as pointed out above the brake backplate is hard against the swing arm with the brace plate over the outer side of swinging arm and the nut that holds the dummy spindle that sits inside the hub. If your can hold a drum to your frame to check chain alignment that is first step.
Then you need to check the wheel alignment once you offer the hub into the brake assembly.  The s/a models have the long spacer mentioned above that goes between the dust cover and the swing arm inner face.
I presume you've looked on Draganfly preunit spares page as there is a good explodes diagram of each.
The reason I'm familiar is that my second bike had no rear wheel and I am assembling hub/brake assembly from bits using my existing bike and parts books for reference!  If you are lucky to find a complete wheel hub from a later swing arm model (B31/3 or B40 etc) the worse thing that might be needed is a wheel rebuild with different offset for wheel alignment (I think the twins have issues with this?).

[Derek996]

Thanks for that useful information Neil. I think I "may" be able to borrow wheel and brake/sprocket that I can try out over the winter to see how it can be done. Wheel offset doesn't worry me, I do my own wheel building, as long as the chain alignment can be achieved.