The 1949 and later rigid rear brake drum/sprocket, are they available?
Not the WD rear brake but the 1949 and later one as fitted to rigid M series bikes. The one as fitted to the plunger frames is also different so won't fit.
The brake drum and wheel hub are riveted together and you have to remove the spokes and rebuild the wheel to fit a new one. BSA never sold the brake drum as a separate part and you had to get brake drum/wheel hub as one part.
Mine was OK when I got the bike 30 years ago but is nearing the end of its life.
The part number for the drum/hub assembly is 66-6259.
Lots of searching has turned up nothing. I am in the USA and am wondering who in the UK may have one?
Hi Bruce..Like the early post war B31, which has a similar set up, sprocket/drums are not available for these wheels..Retoothing or replacement with a better example is the only solution...Retoothing is not easy due to the proximity of the root of the sprocket teeth to the drum and the thin drum walls...I ran an early post war M21 for a number of years with this set up and when the rear spindle broke (another problem that is not unknown with the type) I replaced the entire thing with a WD wheel for which parts are more readily available..You can retain your original brake plate/shoes for this conversion if memory serves...Ian
Thank you for the information Ian. The bike is a 1950 M21.
So it looks like if I want to keep the current wheel, I will need to make a new brake drum. I was hoping to avoid that but as I have a lathe and mill at home, it is not an impossible task.
As BSA used this wheel for more than 10 years, I wonder why no one makes new brake drums for it? I can't be the only one who needs one.
Now a more important question, the axle on this wheel can break??????? Where does it break on the axle so I can inspect it for cracks? I will be riding 300 miles on the bike this Saturday and now have another thing to worry about!
