[SOLVED] Howling disk brakes: What else to try?
 

Hello,

On a sunny day, even with brand new Shimano brake pads and disks thoroughly cleaned with Bardahl cleaner and even sandpapered… the brakes still squeak.

Before buying a pair of new rotors, is there something else I could try?

Cheers,

MAFACs.

(Could be quieter...)

mix up some mud, about pancake batter consistency... then smear the discs and let it dry halfway...... then go for a ride.
i've even just tossed DUST at a squealing disc, after getting it wet with water from my water bottle, to shut it up... the Specialized enduro bike comes to mind....

just curious.. what Grit and TYPE of sandpaper did you use?

When do they squeak? Every time you brake while riding. Or just when you are moving the bike around the shop or storage area?

I know you've probable said what you have sometime in the past. But since many of us don't have identic memory, it'd help to say what brand and model brakes you have. And maybe when the problem started. And maybe the circumstances for when it started.

Is it a mix and match brake components. Or all from the same series. Including rotors and pads?

My Shimano 8000 series brakes are now going on 9000 miles, pads included. And virtually never has squeaking or squalling been a issue. Only in the wet, do they hint at a squeak.

Maybe you fiddled with and worried about them too much.

I don't know what Bardhal cleaner is but isopropyl alcohol is what you should use and find a safe space to set it ablaze both rotors and pads and I usually do it twice and then spray with alcohol while still hot to help cool down and also one final cleaning. That should help burn off contaminants and then ride the bike down a hill dragging the brakes and do it again and again and that will generally solve the problem

Thank you for helping prove the point I made on another thread discussing why these forums are like a bunch of old men yelling at clouds. The old timer, vintage bike enthusiast can’t help themselves and inject inane cheap shots into normal threads involving current technology and issues.



Imagine if the vast majority of cyclists who are utilizing current tech did the same thing over in C&V. I could start with the 1,400 post thread discussing the most mundane bike brand Bianchi whose only value add to the sport is a bizarre color. It goes on infinitum. You mention Mafac a bankrupt OEM supplier to mass production bicycles. Not known for quality or stopping.



Go back to C&V and discuss the proper Pantone shade for Blue Masi or decode the serial number for a outsourced bulk produced Colnago.

Just some light sandpaper because I've never done it before.

Only when applying the brakes. Just pushing the bike with the brake slighty pressed does it.

It's a second-hand bike, I don't know what the owner did with it. All the parts — rotors, brakes, and pads are from Shimano (Deore BR-M6000, BP-G05S-RX, Deore SM-RT56). Like I said, the pads are new, but maybe the rotors can be contamined enough that degreasing doesn't fix it?

I'll try isopropyl. Not sure I'll go ahead with setting them ablaze. If that doesn't work, I'll just get new rotors.

Yes try setting them on fire in a safe spot. Trust me you are burning out contaminants. You could also just burn them with a torch but I prefer just going outside and burning them. It helps greatly and could save you from having to replace rotors.

This is a quote from the Bardahl cleaner link. If this is what you used this is a CLEANER-LUBRICANT. Not for use on pads

"3. Brakes - calipers

On brake calipers and small mechanisms, apply Bardahl Multi-Function Lubricant.
Be careful, be very careful when applying to the calipers, especially do not apply to the pads or discs.

What product to use?

Multispray

• Multispray 50 is a multi-purpose lubricant degreaser consisting of a synthetic base oil and a powerful corrosion inhibitor system.
• Penetrates deep.
• Cleans and dissolves residues (oil, grease, tar) without leaving deposits.
• Protects against moisture, oxidation, and corrosion by covering the surface with a light oily film."

Measure the rotor thickness. My old Shimano Ultegra rotor screamed - even after cleaning, sanding and burning, plus new pads.

It was right at the minimum thickness and replacing it ended the noise.

Atlas Shrugged I don't agree with everything you said -- and that's OK! -- but you made me laugh out loud. Now get off my lawn! (just kidding, promise)

ok try a much coarser grit, like 120 or even 80 grit.. and Do Not Use Regular Tan colored "Carpenter's " Sandpaper.. Use Emery Paper, the good Black kind.. the Tan paper leaves behind a smear of the cheap Glue the grit is put on the paper with..
a rough surface prevents the short duration "stick and release" cycles that we hear as a Squeal...

i have Never, and will Never, Burn a Disc with any flammable substance. The Thin Discs bicycles use can be Warped by uneven heating and cooling, very easily.

... jumping ahead about 40 posts... Winfried will try all sorts of things, and there will be a lot more things proposed to eliminate an annoying sound from the bike... at some point Wini will decide to give up the fire dances, expensive chemical experiments, and voodoo chants, then go buy a new pair of calipers and pads... problem solved.

Alcohol burns nearly invisible, especially outside, during daylight hours... it nearly explodes when misted into the air, then ignited by a previously unseen remnant flame... i've watched such a tragedy happen at an Indy Car race.... people jumping, screaming and running, from flames no one else could see...
on the good side.. none of them had to shave afterward.

Timely post; my front brake just started howling. TRP HY/RD. Started after riding in the rain on a trip. Will try some of the tips here. Thanks.

As a full time mech in the past, I had worked on hundreds of disc brakes on bicycles. Not a single time did burning out contaminants do anything other than provide some entertainment for a short period (I am a fire bug). What I have found is brake pads loose in the calipers. In fact, the BB7 calipers I just installed on my new touring frame howl like a coyote in heat. No question the pads are loose in the calipers as I can feel them rock if I do a loose headset check.
One very odd thing I did encounter on a brand new out of the box Specialized road bike outfitted with Sram Force brakes and Roval wheels. The front brake howled loudly, louder than any brake I had encountered up to that point. After cleaning, burning, and then replacing everything with new from Sram, the solution had nothing to do with the brakes at all. It was the front wheel.
Nope, the rotor wasn't loose, the bearings were not loose(not that I could tell). Taking the front wheel off the exact same bike in the showroom, the thing howled, however going up a model in Roval wheels, the howling went away. After discussing this with Specialized, they sent me a set of the next model up wheels and never heard a complaint from the front brake again.

Honestly sometimes Shimano brakes just decide they want to sing lol.

I'd recommend you don't get in too big a hurry to fiddle with it. It might take care of itself on the next trip or two.

Sometimes the only thing that seems common in these squalling brake threads is the OP messed with the brakes as soon as it started. Or even before!

I watched the Pro 1/2 race at the Tour of Somerville, heard squealing brakes before a crash and thought, "Well if these top level racers on super expensive carbon bikes have squealing brake problems then I don't feel so bad!"

Indeed, I did use that light, tan colored sandpaper. I'll keep that in mind the next time.

Since I read about acetone and had some handy, I gave it a try… and problem solved. I'll still get a bottle of isopropyl alcohol for testing purposes.

Thanks all.

Squealing and contaminated disc rotors: the bane of my existence.

Yesterday, client came to the Co-op needing some new pads. His efforts to remove the corroded pad retaining pins resulted in him releasing liberal quantities to WD40 to everything in the caliper region. Plus the rotors. Zero braking of course.

Pins had to be drilled out. Didn't have enough money to buy new pads and rotors, so he tried for hours to clean/sand the rotors and pads with weak degreasers such as isopropyl. Of course, this was total futility.

Only success I've had with cleaning badly contaminated rotors was using liberal amounts of fine-grain sandpaper, completely clean towels and a good degreaser such as white gas (camp fuel). Of course this was done outside using considerable care due to the inhalation and combustion risks. And the whole process involved 2 hours of tedious work.

Never have this magnitude of problem with rim brakes.

Fire works!!

I just had issues with 4 of my bikes - all of them were honking like wild geese. Sanding, brake cleaner... nothing worked.

I laid the pads on the ground and fired up my Harbor Freight weed burner (which is a fairly powerful device) and blasted the pads.

No more honking.

fify.

I have a question that's been on my mind for a long time.

When will the disk brake manufacturer's address the Squealing Rotor Syndrom? This is why I'm asking this question:

Rotors do and will get contaminated, that's a given. Knowing that, and knowing that riding in the rain kicks up all kinds of oily and asphalty road grime. Chain lubricant can fling off the chain, a misplaced sprits of bike cleaner or any other physical matter that may be in close proximity can come in contact with the rotor.

So knowing all of that, when will the brake makers address this? Are they working on a new rotor and/or brake material, or design, that is resistant to this sufficiently enough to not squeal?

I'm 68 and think that disk brakes are awesome. I also like my old caliper brakes too - and yes, they have their idiosyncrasies as well. But, I think it's high-time the brake makers directly address this.

For me, I am anal about brake maintenance and rarely have squealing brakes. But when I do, just like the rest of you, it's a pain to get rid of it.

Thoughts? Let'er rip...

It was a joke, it made me smile. All that anger isn't doing you any good.

Good point. Automotive brakes don't squeal regularly. Neither do motorcycle brakes. So it should be solvable