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[rustygman]

After work yesterday when I applied my back brake there was a solid clunk sound and my rear drum locked solid. I loosened the adjuster, pressed the pedal a couple of times, readjusted the brake and off I went. Now the brakes had fairly recent new shoes and my annual post winter greasing of the brake cam. It had rained very heavily in the morning so I think there is a link here, the brake is fine again today. Any ideas what is happening here, it is a bit dangerous but I am sure it is linked to water ingress. Its a 2007 indian bullet with 30k under her belt. Any advice welcome (all my posts seem to end with that line). Thanks.

[sofiaspin]

Had that nasty surprise. Danp expanding pads in my case

[ric]

Check the tightness of the pivot pin nut.



Sounds like the brake plate has rotated and the brake arm has moved, the brake rod hasn't lengthened so what happens is the brake activates, with no slack in the system the cam locks the shoes hard against the drum.
You've slackened off the rod adjusting nut allowing the brake arm to reposition itself thus restoring the status quo.


I always tighten the big nut first with the pedal pressed down to centre the shoes, then with the brake still applied rotate the wheel in its normal direction of travel to ensure the pivot stud is hard against the lug, then tighten the pivot pin nut with the brake still applied. Unless the nut works loose the brake plate cannot rotate.

[PeteF]

Wet shoes can make brakes very grabby.

[Tim NZ]

Locking rear brake?


a: the cam binding/seizing in the housing?


b: weak or broken springs; brake shoes and or lever?


c: the rear brake lever has been repositioned so that angle between rod and lever is brought back from 45 deg to 90 deg; AND one of the linings is worn out?
d: broken pce of brake shoe heel floating in the drum...


e: incorrectly assembled plate and shoes, (croocked to axle and drum) spacers missing or in wrong place, anchor/pivot nut loose, buckled/distorted brake plate.




Water in the drum? You wont have any brake...


Too little free play in the system will cause the brake to drag when the bike is loaded or used over rough surfaces...


In which event the Linings will have been burnt, Cush rubbers melted, Drum 'blued' and the Hub bearing cooked...

[Bullet Whisperer]

It might be a damp atmosphere has very slightly rusted the inner surface of the brake drum, making the brake 'grabby' the first few times it is applied. If you watch just the first minute of my video, you will hear a grating noise from the rear brake 3 times before I cross the railway line. A lot of them do it and it can be quite alarming, but it settles down. A lot nastier was when a double sided Grimeca front brake did it on a race bike a few years ago and fired me over the handlebars, while I was push starting it! Best to apply the brakes gently a few times at very low speed when setting off to avoid this taking you by surprise later, at higher speed. Regards, Paul https://www.youtube.com/watch?v=WfSz1z1iz1M

[jefrs]

Binding, shoe alignment and brake adjustment - If the lead shoe throws too far onto the drum, it can stick there (it can also bind if the spring has come off). And new shoes do need to bed in.



There are two small screws on the brake arm pivot. These are usually painted into place. The design is supposed to move to align the shoes, that's why the two small screws have lock nuts on the outside, the screws are not supposed to be fully tightened, nor painted in place. Hence scrape the paint off and free the screws up and nip them up so the pivot plate can just be moved by foot pressure on the pedal, then nip up the lock nuts. It does want to slide but does not want to be slack, maybe a tiny smear of copper grease under the pivot (not paint). Stomping on the brake pedal will align the shoes, now adjust the brake pedal rod so there is the normal slack before the brakes come on. Having both shoes working makes a lot of difference.

[rustygman]

Just an update. Have not had time to check anything as yet as working long hours but used the bike every day since and the brake is operating perfectly so I am thinking it must be something to do with wet shoes and rust forming over the day on the drum (maybe?). Bloody extreme grabbing though, it was a solid locking of the rear wheel. I have dabbed the lever a couple of times before starting just to make sure and will see how it goes. My mechanic had the bike about a month ago to fit new shoes and I would be amazed if he had not put everything back properly - he has been working on these things since the 1950s. Thanks for all your comments.

[steve hunt]

Same thing happened to me luckily just yards from home tested brakes and back brake locked up solid. striped down back brake and found pieces of brake lining, buckled back plate, broken brake shoes, and bent pivot bolt. I think the previous owner hadn't chamferd the end of the shoes, and I hadn't had any reason to check them. I had a lucky escape as only doing about 5mph. steve