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Luddite
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My R50 has always suffered from brake squeal. It’s the type of squeal which wakes neighbours up when I pull the bike up outside my house, they have informed me. So I need to do something about it really, before a polite complaint becomes a punch on the nose.

I’ve checked the cam pivot shafts for radial and axial play, they seem OK; I’ve changed the linings, and chamfered the ends properly, and it’s still there. The drum liner is uncracked, clean and shiny with no unusual grooves. I’ve tried packing the brake anchor to remove any clearance to no effect. I’ve centred the backplate, and checked the wheel bearing clearances.

What am I missing?

Twocams
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VBMWMO #8750
Joined: 03/16/2014
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The drum is "clean and shiny"

The drum is "clean and shiny" that could be your problem. You need to kick some dirt on it. kidding. If you have ever seen a brake drum or rotor after it came off a brake lathe. They are dull to look at. I would take some heavy sand paper (by hand) and ruff up the inside of the drum/ shoes. Its like taking a piece of glass and rubbing your finger across. Are both doing it or just one?

twocams

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Twocams
69 R69S 03 K1200GT
92 R100RT

Luddite
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By 'shiny' I meant 'not

By 'shiny' I meant 'not rust-pitted'. I've broken the glaze on the drum when I stripped the front wheel, however, that is one thing I haven't covered properly, so I will crosshatch the drum and see what happens. Or hear what happens.

Twocams
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VBMWMO #8750
Joined: 03/16/2014
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Also If the drum its self is

Also If the drum its self is getting to thin can cause noise problems. Not necessarily stopping trouble. Also the type of shoe material being used. In the old days it was a lot of asbestos material. Now they are using different bonding materials. They say and have been for the last 50 yrs. to ark the shoes to the drum. I have never found it necessary but who knows. Have you tried taking the shoes off the backing plate and putting them inside the drum? Then just pushing them around inside to see how they conform to the inside of the drum. Im not talking about taking the rivets out/just the springs off. I know it can be annoying, my 92 R100RT front disc brakes were bad. think I got it for now tho.

twocams

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Twocams
69 R69S 03 K1200GT
92 R100RT

jambo
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VBMWMO #9208
Long Island
Joined: 11/23/2016
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Show material?

What shoe material did you use when you replaced it? Did you go with the Ferodo lining or the original type?

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James W.
1966 R50/2, 1963 R27 and 2018 R1200GS

Luddite
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I used the standard linings

I used the standard linings from UK company Saftek. They look pretty much like most nonwoven modern linings, I chatted with the guys from Saftek about bike usage, weight etc before arriving at that lining.

Luddite
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STILL SQUEAKY

After yet another rebuild, the squeal is still there.

Glaze removed from drum, surface crosshatched. Shoe contact patch checked and found even and equal. Chamfer redone. Pivot points re-re-re checked and still found OK. Cable smooth. Shoe gap reset, cable reset. All this and it still squeals!

What am I still missing?

Twocams
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VBMWMO #8750
Joined: 03/16/2014
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Sounds like you have covered

Sounds like you have covered just about everything. I assume it has spokes. Are any to tight/or to loose. It would only take a couple.
How about tire pressure? Have to tried as low as say, 28 psi Maybe as high as 35-40 psi. Hey, Im just "grabbing at straws" see if anything sticks. Have you tried moving the wheel back to front....or switching the drums around. i know some of the pre 70s can be. So it sounds like a drum problem to me.

twocams

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Twocams
69 R69S 03 K1200GT
92 R100RT

mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
Could be spring vibration.

Could be spring vibration. Later BMWs used a sleeve over the brake spring (rear brake naturally) to combat noise.

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Mark
qualitycycleservice.com

c8h18
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Joined: 10/14/2012
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A last resort, but it worked

I had the same problem, and like you all things were in their place and well accounted for. Don't ask me why but, as a last resort, we switched the wheel positions. Front to back and moved the back to the front and cut the noise by 95%. Virtually noise free. Go figure. I am sure there is a logical explanation that someone smatter than me can conjure and yes it was a total PITA. But like I said. A last resort.

Captonzap
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Check the tension on the

Check the tension on the spokes, and see if they are the same on both wheels.

CZ

Luddite
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OK, early days yet, but I

OK, early days yet, but I seem to have eliminated my squeal by shimming the pivot posts for 0.2mm clearance between shoe and backplate rib, andso there's no axial clearance but still smooth movement. In an hour's backlane riding, not a squeak. My neighbours will be so pleased!

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