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Rubbing rear brake Diagnosis and adjustment.

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1967 R502
Posts: 143
Joined: Thu Jan 25, 2018 11:47 am

Rubbing rear brake Diagnosis and adjustment.

Post by 1967 R502 »

The top rear brake shoe on my R50s seems to rub on a particular part of the hub. I say it is the top shoe and pad based on that is where I hear the friction coming from.

I can run the thumb screw on the brake rod all the way out and still get friction.

I do not think the drum is oval. Why? It honestly has not seem that much use since restoration and the rubbing is asymmetrical. The spot 180 degrees across does NOT seem to rub. Maybe this means nothing. Maybe I should expect asymmetry. I don’t know.

The wheels were recently balanced as well.

Visually, of course, there is not much to see, with the wheel on or off the bike.

Any suggestions on how to proceed and how to adjust would be appreciated.

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plusvee
Posts: 31
Joined: Sat Apr 22, 2023 7:36 am
Location: Italy

Re: Rubbing rear brake Diagnosis and adjustment.

Post by plusvee »

My two cents:
You have to proceed by exclusion. Does this noise also occur when you move the bike by hand with the engine off? If so, disassemble the wheel and remove the brake shoes, reassemble the wheel without brake shoes and move the bike by hand (with the engine off) for a very short distance. If you can still hear the noise, it's not the brake shoes. If you don't hear the noise, there are two clues: the brake shoes are not installed correctly[1] or the brake spanner is not installed correctly (this happens when the brake rod is also removed when replacing the brake shoes, sometimes the brake spanner rotates slightly; if it is installed in that way, it's not in the correct position even though it appears to be! This causes the brake shoes to be wider than normal, producing friction on the drum even if you are not braking) Time required for this check: 15-20 minutes.



[1] I assume are not oversized pads.
Marco

R50/2; R60/2; R69S; R12; R71;

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