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[MajorMajor]

I finally bought a rear stand so I can now share my rear brake squeal (5 sec. video). Notice the noise near the end when I apply the brakes.



It's been doing this since it was a couple of weeks old. 3000 km on it now.
Keep in mind that the squeal you hear in the video actually goes on for a few seconds until the bike comes to a stop (when not on a stand).

Regen is set to 0 for the demonstration.

P.S Extremely sorry for the vertical video, I was balancing on one leg, giving it throttle, keeping an eye on wheel speed and pressing down on the brake. Slipped my mind

[BrianTRice@gmail.com]

That doesn't sound like the squeal I'm used to (for the 2013 DS), just a minor squeak, maybe just as your pads are wearing in. In the video, it doesn't sound louder than the power train, which is pretty quiet.

The squeal is when the pads resonated against the calipers, resulting in a loud metal-on-metal tone.

Have I heard incorrectly? Thanks for documenting this pretty well, in either case, and in doing it on a stand where it's easier to isolate issues.

[MajorMajor]

It's so loud that I'm embarrassed to use my rear brake at low speeds (speeds that regen doesn't work on).
The drive train might be louder than you expect because it's picking up speed really quick.
I'm braking at around 60-70 km\h.
I'd like to find a way to record the sound while moving but I'm not sure how to do it.
Maybe my wife can run after me for a bit...

[BrianTRice@gmail.com]

Okay, so the audio doesn't carry across how I expected, and you have a squeal. There's a recommendation that's been collected for brake squeal that works for some, basically a Loctite solution:
http://zeromanual.com/index.php/Common_Problems#Brake_Squeal

Otherwise, definitely check the brake pad section of the unofficial manual for a solution:
http://zeromanual.com/index.php/Unofficial_Service_Manual#Brake_Pads

For my 2013, I find that I just wind up periodically forcibly re-seating the pads once every few weeks along with a quick cleaning when a squeal occurs. My 2016 is somehow immune but others have reported the issue (fewer than for 2013-2014 at least).

[Richard230]

BMW motorcycles have had loud brake squeal off and on for years - dating back to drum rear brakes during the 1970's, in my experience.  Then when they changed to disc brakes, those sometimes squealed loudly, too on some models.  My recollection is that usually a change in brake pad material, as well as keeping the drum or disc clean of dust, typically solved the problem, eventually.  Oddly, the squeal only occurred on some bikes and not all of a particular model - which resulted in BMW not usually doing anything about the problem until designing a new version of the vehicle and likely making some modification to the brake components.

[MajorMajor]

I'd like to try fixing it myself before taking it to a mechanic.

How do I forcibly reseat the pads?
How do I clean it? There seams to be almost no distance between the pads and the disc.

[BrianTRice@gmail.com]

I'd like to try fixing it myself before taking it to a mechanic.

Sure, this should be easy.

How do I forcibly reseat the pads?

This is just about making an intentional braking pattern where you progressively press on the brakes (rear in this case) really hard. The idea is hopefully to push out any grime that's preventing the pad from sitting against the caliper properly. I just do this a couple of times when a squeal comes up.

How do I clean it? There seams to be almost no distance between the pads and the disc.

Oh, you want to clean the outside of the pad as it faces the caliper, not the disc side. That's where that Loctite formula above also applies. Just spray some WD-40 brake cleaner on it and wipe it down. (EDIT: WD-40 is a penetrant not a lubricant and this can cause problems if it gets into the brake system or just makes the surface worse at its job.)

I stumbled on this article googling which seems fine enough. They also point out that shims sometimes work.

http://www.popularmechanics.com/cars/how-to/a3092/4317748/

[Richard230]

Sometimes dirt can be washed away with a stream of water, other times the pads become glazed during use and need to be removed and sanded on a flat piece of glass to remove the glaze. Also, sometimes braking hard from a high speed might rub off some of the foreign material on the pads that might be causing the noise.  If none of these methods help, then new pad material is likely the solution.  Unfortunately finding the right pads might be a relatively costly trial and error procedure.

If it was me, I wouldn't get WD-40, or any other lubricant, anywhere near my pads or brake disc.

[BrianTRice@gmail.com]

You're right. The WD-40 suggestion was careless. Thanks.

[MajorMajor]

I'll start by spraying a stream of water at it and see if it helps.

Is soap OK to use?
Is that a good idea?
Should I be worried about rust?

[BrianTRice@gmail.com]

Compressed air or brake cleaning fluid would be better than water, but I don't think it'll specifically hurt. Brakes don't rust if you use them regularly.

[Richard230]

I'll start by spraying a stream of water at it and see if it helps.

Is soap OK to use?
Is that a good idea?
Should I be worried about rust?

You can use auto washing detergent and a sponge to wipe the disc and then spin it to get the detergent mixture into the pads. Then follow up with a stream of water from a garden hose.  I have been cleaning my discs and brake pad interface for years without any problems.  I follow it up by drying the disc with a clean towel and then going for a ride up and down a hill, while using the brakes, to make sure that they warm up enough to thoroughly dry all of the brake parts. That way you can be sure that you will not get any rust spots on the (stainless steel  ) disc.   

[Kocho]

I recently replaced my OEM front brake pads with EBC organic pads in an attempt to eliminate the annoying loud squeal at low speeds when the bike is about to stop fully. The new pads did minimize that significantly, but unfortunately did not completely eliminate it. They also introduced a new flavor of noise that was not there before, but that is not anywhere as annoying and loud as the squeal was before. Spraying brake cleaner and wiping off the runoff from it did not help.

Replacing the rears with the same type of EBC pads did solve a similar rear brake squeal almost completely, so quite happy with them in the rear.

Compressed air did absolutely nothing in my case to eliminate the squeal from the original pads and IMO shouldn't really do much if anything since if the material would not dislodge from hard braking I doubt it would from some air blasting at it. In my case the brakes squeal not because there is something between them and the disks - they just squeal because of vibrations, so cleaning won't help. My car's brakes (even with drilled rotors, while I had them) are much smoother and quieter than my bike's brakes, so there has got to be a way to do quite brakes ...

[BrianTRice@gmail.com]

Did you try any spacers or the loctite?

[Kocho]

No, I did not try spacers or locktite. The noise is down enough with the EBC pads to not be bothering me. I might put some brake "goop" on the outside of the fronts to see if that helps further.