Sounds from brake drum

[Athame57]

I've been getting a long strange sound from the rear brake drum under gentle braking.    This stopped a while after fitting new shoes    but it soon started coming back again.    I'm wondering if the drum has started to go oval. Could that be the cause and can it be repaired?

[Bryanj]

Only oval if the brake pedal pulses under your foot.
The noise could be dust in the drum

[Athame57]

Only oval if the brake pedal pulses under your foot.
The noise could be dust in the drum

A bit of a relief, thanks Bryan. I have misplaced the dust seal I got of Julie, so it never got fitted. Maybe I should order another one off her when she gets back!  

[exvalvesetdabbler]

A good clean up inside the drum, (Caution!!!! - do it with a wet cloth, bag and bin it as it might be asbestos dust), particularly in the void beyond the brake drum that seems to collect a lot of muck that might now have got dislodged and ended up between the shoes and the drum. Degrease the braking surface and shoes to remove any oily thumb prints.

Also worth checking that the new shoes have a decent chamfer on the leading edges.

If the drum has a wear ridge, the difference in diameter where the shoes rub compared to the edge of the drum that don't contact the shoes, it could just be the edge of the shoe rubbing on that before it drops into the drum under heavier braking. Only need the new shoes to be fraction of mm wider or offset than the old shoes.

On old cars with drum brakes it was a common theme and usually come down to grinding down the ridge a bit, and was sometimes a ball ache getting the drums off if the ridge had swelled up due to rust and the adjusters couldn't be slacked off enough.

I would give them a chance to bed in and hopefully the sound will go away.

Regards
Dave

[Athame57]

particularly in the void beyond the brake drum that seems to collect a lot of muck that might now have got dislodged and ended up between the shoes and the drum.

Thanks for this Dave, I never thought of that. I had better get the back wheel out again I think, I'll wait until I find this dust seal I have or get another one though.

[exvalvesetdabbler]

As well as the dust seal make sure the 14mm washer is there as well. #392 on the drawing below.

When attaching the brake arm onto the splined shaft make sure that it is fully on and there is no in/out movement on the shaft.  You need to squeeze it from both ends by hand before tightening up the nut.

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Regards
Dave.

[Athame57]

As well as the dust seal make sure the 14mm washer is there as well. #392 on the drawing below.

Thanks for this Dave. The washer ( part # 90549121000 ) doesn't look like just any 14 mm washer, can't be had on cmsl or DSS, nor did google and ebay search help.  I guess I'll have to improvise!

[exvalvesetdabbler]

Looking at the limited images for this, it looks like a thin shim washer or just a skinny flat form washer. perhaps someone reading this that has one to hand cold get their calipers out and report back.

This any use?

https://www.accu.co.uk/shim-washers/62804-HSHN-14-20-1-A2

Dave

[Athame57]

Hi Dave
I've ordered one, we'll see what happens then! 

[exvalvesetdabbler]

Just been  trying to find my spare brake plate but it might be hiding in the loft.

Honda part code beginning 905 is a non standard item so as you suspect a bit of fettling might be needed.

I suspect the washer goes into a recess together with the dust seal and is probably there to keep the dust seal in place and not get chewed up by the break wear indicator plate.  Don't think the absence is responsible for the noises heard, just means the dust seal may work its way out a bit and not do it's job long term.

Might be worth having the bike on the main stand and spin the wheel by hand while gently applying a little brake , is the noise kind of even all the way round one wheel rotation or just a tight spot in one place.

Regards
Dave.

[Athame57]

Thanks for that Dave, I've ordered one. 

[McCabe-Thiele (Ted)]

Reading this thread does make me think that as long as the main brake pedal is not fluttering as per Bryans post it's no surprise that under gentle braking there is some noise most likely from the leading shoe.

Both rear brake shoes are activated by the turn of the shaft that effectively means there is one leading shoe and one trailing shoe. Under very light braking the trailing shoe does very little, the braking starts on the leading shoe hence possibly  the longer noise. With the removal of asbestos in modern linings that might also account for the noise under very light braking. I would not be too worried myself once you are sure it's not linked to accumulated brake dust.

[exvalvesetdabbler]

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Removed the arm from the spare brake plate I had stored,  nothing,  no dust seal, no washer

Regards
Dave.

[Athame57]

EEEEK!  Mine isn't that bas Dave. However the bits arrived today, but after nearly earning myself a hernia fitting my new header pipes/collecter box I've done enough for one day! 

[exvalvesetdabbler]

If the headers are on and you still have all the skin on your knuckles the I would chalk it up as a win. 

Just keep an eye on the nuts that hold the headers on, they might just need a quarter turn once things have settled in or if you hear a bit of a crackle around them with the engine running.

Regards
Dave