Rear Brake

[Ozmadman]

I have just had to re-adjust the back chain on my bike due to fitting a longer chain to cope with the new 20 tooth gearbox sprocket and have noticed that when turning the back wheel by hand the brake shoes seem to be hitting/catching on something as the wheel turns. it's like the leading edge of the shoes are catching as the drum spins resulting in a clonk once every revolution. This isn't anything to do with the clonk when applying the rear brake that is the result of the slot in the brake plate/ spigot on the frame being worn as I had that part welded and machined to fit the plate so that is a perfect fit and anyway this is happening without using the brake. If you undo the wheel nuts a bit it lessens the clonk but it worse when they are tight any ideas?? i have all the washers and spacers in the correct places.

Thanks Paul

[Rob Harknett]

Watch to see if the chain has a tight spot riding the sprocket teeth, then clonking when it loosens.

[robcurrie]

+1 Rob, also, make a mark on the tyre and a mark on the chain so that you can see if it is linked to the revolution of the wheel or the chain.

Rob C

[Ozmadman]

Not the chain as it does it with the chain off, definitely something to do with the brakes/linings/brake drum/brake plate? Read somewhere about centering the brakes? Could this be the problem? Can someone enlighten me how you do it?looks like the full chain guard has to come off again, what a pain that is!!

[Janet]

I was thinking that if the brakes aren't centred and the drum is a little worn it could catch on every revolution. However, I'm useless at diagnosing causes.
To centre the brakes, loosen the lhs spindle and brake plate lock nuts. Apply the brake, hold it on and re-tighten the nuts. Repeat if required, perhaps after turning the wheel to a different position.

[Rob Harknett]

I assumed this would had been done. But not always it seems. I brought a lightweight CSR and the rear brake clonked every rev, the foot brake punched my foot. The Suzuki front wheel gave first class braking. I looked like a small Norton type hub wheel. A Jawa prop stand also fits in place of the nearside footrest.

[robcurrie]

Rex will tell you to check the springs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Rob C

[Ozmadman]

Rex will tell you to check the springs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Rob C

What's there to check?

[Janet]

Rex will tell you to check the springs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Rob C

What's there to check?

Perhaps he means the springs holding the shoes in place. One of them could have broken or come detached.

[Janet]

Are you absolutely sure the noise is coming from inside the brake and couldn't be something else, such as a broken spoke sticking out at the other side of the wheel from where you're looking? It could be coincidence that it's happening now. If nothing else, it's another suspect eliminated from your enquiries.