Squealing From Shimano Disk brake
 

OK, so first thing I would suggest is to "align" the caliper as follows :

- loosen the two caliper mounting bolts about a full turn so the caliper is able to move a little bit
- wobble the caliper a little bit so it is truly loose
- squeeze the brake lever 3-4 times and then "hold it" - use an assistant or a rubber band around the lever
- now with the brake lever clamped down locking the caliper in place, tighten the caliper mounting bolts
- be sure to snug them both down, and then torque them to final torque - don't just tighten one and then the other.

and then do a test ride. See if that doesn't help. Report back.

if it's still squealing then take the pads out and look for even wear - make sure you don't have one pad "cocked" inside the caliper

but I'm betting this will help. I do this whenever I change pads

/markp

Of course you are missing something. If you weren't they'd be working correctly and not making any noise.

What the issue is I've no idea. So not worth venturing any of the typical things. I'm just glad I've not had any issues with mine. I've got over 5000 miles on the original pads and they still aren't near the replacement wear Shimano suggests. Maybe I should use them more!

I know Mississippi isn't completely flat, but try riding in the Rockies! On a good year I climb a quarter million feet. I change my front pads every year, with only 3000 miles on them. Rears last over twice as long. I keep a couple sets in stock.

To the OP, if it's not alignment, consider a new disc. If it got contaminated with brake fluid, it may not be salvageable.

had a squealing problem

caliper alignment checked out - was good

rotor / pad light sanding and cleaning (iso alcohol) stopped the squealing initially - but then it returned after a few rides

replaced the pads and now no issues

original pads were J03A - replacement pads the newer J05A

still have J03A pads on another bike - similar rotors - many more miles and no issues


you could try the squeal out stuff - heard that works well - but I just replaced the pads

Seeing as it's your front brake, check for play in the Headset.

Barry

Disc brake squeal is a common issue, not only in bikes. It's caused by pad vibration and is usually worst with light braking (slowing, or holding speed on descents) and stops at higher braking force where they're pressed more firmly against the disc. Generally, but not always, it resolves over time, but may return under certain conditions, like rain or high humidity.

The key is to address the vibration and here's two tricks.

1- reduce "bite" by chamfering the leading edges (toward back of the bike) slightly before mounting the pads.
2- on my car, I use a light adhesive when installing the pads. This increases stability and prevents squealing. Can't say about bikes because I don't use disc brakes there, but it should help.

If it doesn't resolve on it's own, and you can't solve it mechanically, learn to modulate brake use around the issue by, for example, using more brake at intervals vs. steady light braking.

I've been using disc brakes for a while on multiple bikes. But recently I made a point to read (or maybe it was a Shimano video) what Shimano had to say about bedding in the brakes. One of the issues mentioned was that if not done correctly, you can get squealing. They suggested getting up to 12-15 MPH and applying only the brake you're working on until you slow to a walking pace. But DON'T come to a stop. Repeat this 15-20 times.

I will say from experience, that I've contaminated brake pads with brake fluid (mineral oil) and no amount of cleaning ever made them usable again. They looked perfect, especially after cleaning and a light sanding. They looked dry as a bone. But still no good. Maybe there is some magic way to clean them, but certainly it's not as simple as just soaking them in a solvent.

Propane torch will clean the pads. People will frown on doing it but it works. Heat those suckers up and burn off any contaminates.

Squealing is usually a contamination problem and thorough cleaning may or may not solve the problem.
There is a product call "Squeal Out" that I use and has eliminated squealing every time I've used it.
I've used all of the above solutions but sometimes none of them work...boy oh boy is it ever aggravating and time consuming. But Squeal Out works.

Have you considered any cleaners you might use on your bike? Especially if you are spraying something on or near the bike. Where is that overspray going? On the rotors perhaps?

If you are having to bleed your brakes whether occasionally or frequently, then you likely have a leak and fluid getting on the pads.

I'd spray the pads down liberally with brake parts cleaner prior, let them fully dry, rinse them with clean water, let them fully dry, & then heat them up with an open flame. Probably not MAPP gas [if you have it still] ; propane should be good enough for the purpose.

I was curious since I actually used MAPP on my pads and wanted to see the temp difference. Turns out "MAPP" hasn't been made since 2008 and the current "MAPP" is actually MAP-PRO and only burns around 150 degrees hotter than propane so it really doesn't matter.

Today I cleaned the rotor with iso alcohol and a scotch brite pad. I also aligned the calipers, but I do not think that was the problem they seem to go back to where they were supposed to and no rubbing. I then took bike on a 65 mile ride but is was foggy and damp so moisture on things. I actually did very little braking this was all in country on roads do not stop. I did notice some squealing as usually but being damp I was not sure. Then I noticed at end of ride it seemed to require more braking to get it to squeal. One nice thing about my set up now is the brake lever free stroke is perfect. When I first got the bike 4 months ago I did not like the right brake going almost to the bar to stop. I manage to finally between some bleeding and adjusting get it to bite earlier. This to me is even more important the squealing brakes. So, the short answer is I will have to see how it goes when I ride more today was weird not much braking at all the whole ride.

Also, what are the equivalent pads that come from other manufacturers that do not have the fins. I cannot always figure it out base on the codes the show that the pads work for. Unless they say 7o70 or shimano R7020 I am cannot tell. Seems the road pads are different that mtn bike pads.

You can spray all manner of goop in there, clean with depleted uranium or whatever, hard pads are going to screech until and unless they are properly warmed up. They are "metallic" so not really a surprise !

when doing track days in the car we would install "racing" pads of a much harder compound.

Especially when brand new those pads howled like crazy. It took between 5-8 heat cycles to get them to where they delivered the promised braking performance and quieted down.

even so, they screeched moderately until warmed up. Quit using them as they were hell on the rotors.

I think there's something to be said for NOT using the hard pads (metallic compounds) unless you are doing mega downhills and such.

for normal around town riding you are never going to develop the brake temps to realize the benefit of hard pads.

I'm currently running Swiss Stop "e-bike" compound and to be honest the first application of the brake there is a tiny bit of howl, they quiet down after that.

Probably not going to get them again. Just regular old shimano pads. "organic"

/markp

These are resin pads supposed to the quietest..

I tend to wonder if whomever is cutting the rotors are not doing it to an ideal RA & just to a "polished" finish?

then you've got some other problem that is resisting conventional methods to resolve.

ISO disk format or center lock ? Front and rear both or front only.

confirm disk attachment bolts or lock ring is / are properly torqued and checked ?

somebody made a comment about chamfering / bevelling the leading edge of the pads.

I might do that next if I were you

/markp

Try the propane treatment?

I had problems with a squeaking front rotor, basics didn't seem to work, so I took a chance and spent the money for a Shimano Ice Tech rotor problem solved. ( Also installed new caliper mounting bolts and made sure the caliper mounting surfaces were as true, smooth and clean as I could by hand.)

With the older rim brakes, we’d angle the pads ever so slightly. No squeaking. Not sure if this would work with disc brakes, but might be a solution.

This is not a thing with disc brakes. Why try to offer advice on something you’re not knowledgeable about?

I had the same problem the original poster described. Like others suggested, I tried all the easy fixes. I cleaned the pads. When that didn't work, I loosened the caliper and recentered the rotor. My last try was replacing the pads. With each 'fix', the squeal disappeared for a short while but returned.

I then assumed there was a caliper issue and took the bike to my local shop. The tech removed the pads and the back side of one pad was wet, indicating the caliper had a leak and brake fluid was getting on the pad causing the squeal. They are working with Shimano to try and get me a new caliper.

I’ve seen / had leaking calipers - unfortunately not uncommon

one caliper appeared to be leaking during the cold winter months - could see slight oil residue on the back part of the pads - but it appeared to improve / go away (for the most part ?) during the warmer summer months

bike often sits in an unheated garage where temps can often be below freezing during coldest part of winter

after rides through a lot of crap I will often will pull the pads and clean the inside of the caliper and surrounding area and check the back of the pads ... q tips work great for this