So my ‘winter’ road bike has flat mount shimano 105 disc brake callipers, the ones with the steel pad retaining pin that can be undone with a flat head screw driver. My winter maintenance regime for this bike amounted to occasionally ensuring the tires were inflated to at least 60psi. Needless to say the calipers have been eaten away by water + road salt and the pads had become so contaminated that the ‘squeal’ when applied could perf an ear drum at 200 yards. So I decided I should change the pads, the screwdriver mashed the head of the retaining pin in the front calliper, so no changing them, I managed to get the rear callipers out. There was still plenty of pad left so I proceeded with the standard disc brake cleaner bath, sandpaper, bath the rotors, sand etc etc. managed to kind of sandpaper the pads in the stuck calliper, I mean I didn’t even bother to remove the wheel…but got the job done. Both front and rear brakes improved but continued to squeal…I tried washing up liquid…again this improved things but brakes still squealed on those longer down hills. I was trying to work out how to drill out the pads when I came across a YouTube video of a guy talking about a product he applied disc squeal something can’t remember…BUT it made me think what about applying a lightly abrasive cleaner to everything…? I mean the calliper and pads etc are stuck so who cares…there is a product in the UK and Ireland called pink stuff it’s a lightly abrasive putty that’s used for cleaning. So I coated the rotor with it and worked the wheel around, dragging the brake so that the pads would lightly grip the brakes. After about 5mins of this the rotor looked spotless, did the same with the rear. This morning I went out and……SILENCE…plus….all the original braking power is back. So like me if you are lazy and love a quick fix, buy yourself a pot of pink stuff and when the brakes start squealing just slather it on and think of me. Bye.
I expected to see a picture of rim brakes…
There is a product already on the market called Squeal Out, which sounds very similar and is formulated specifically for bicycle disc brakes.
It works really well, but doesn’t permanently solve the issue and will eventually need reapplication. I would assume this will be true with Pink Stuff, as well.
Over the winter I changed my brake calipers and when I started riding again in the warmer weather, massive squeal.
Manually cleaning both rotor and pads didn’t help so I tried squeal out about a few weeks ago. It got rid of most of the squealing but I couldn’t get the final elements of squeal out, when I braked to stop the bike.
Trying new pads resolved it.
I haven’t used it yet but this was in the middle aisle of my local aldi:
Cycle Brake Cleaner 500ml | Tru-Tension Cycle Brake Cleaner 500ml -
Yeah ‘squeal out’ was the product, the guy mentioned only to treat one wheel at a time because the braking power was reduced by ‘80%’. Pink Stuff isn’t a bicycle specific product just a household cleaner but I found I could apply it and after spending a few minutes working the wheel around it was good to go. Braking power was restored 100% and no squeal.
He’s just being safe. If you live in an area in which you don’t really need to worry about cars, like a suburban neighborhood, you can do both. Or at least I could. I could easily go slow (less than 12 MPH) and stop safely if I wanted anytime, conditioning both brakes.
There are a lot of different abrasive compounds on the market, and some of them smell the same as Squeal Out. It was pulled of the market for awhile, maybe too close to someone’s compound.
I got really good results with a brass wire drill brush for the rotors, and iso on really fine sand paper. I think the brush scuffs up the surface and removes contaminants and the iso scrub exposes new bad material. Just be careful to sand the pads flat and not complicate things by adding an angle to them. It’s easy to do.
(The squeal Out smells and feels like standard rubbing compound like seem at auto parts stores, unless they changed their recipe. Squeal Out didn’t work for me, not sure why.) (I have tried using fine sandpaper on the rotors, and it has quieted a few down nicely 
)
Excellently timed post as my back brake has recently developed a horrific squeal which was on my to do list this weekend. Should be plenty of life left in the pads so was going to try my usual approach of fine sanding the pads and cleaning the rotors, but have had mixed results with that previously (normally at least reduces the squeal bit doesn’t always eliminate it). Already have Pink Stuff in the house so will give it a go. Pink Stuff instructions say to rinse off with water after cleaning - did you bother with that step or just let it rub off? Probably a moot point looking at the UK weather forecast, they’re going to get a good rinse soon enough anyway…
After applying and spending some time dragging the brake and turning the wheel I wiped off with a clean rag and made sure not to touch the rotors. I also tried leaving it on, both seemed to work well. I would say make sure you spend some time dragging the brake with the bike in the stand / upside down when you first apply it. Pink stuff drys fairly quickly, what’s left will flake off quickly once you are out on the road.
You can purchase squeal out on Amazon uk for £55 vs £1.50 for a jar of pink stuff. I have to stop saying pink stuff…let us know how you get on.
I’m using isopropyl alcohol (99%, not 70%) and 120 grit wet/dry sandpaper.
Level 1 – wipe down rotors with alcohol on a lint-free rag/shop towel
This fixes it most of the time (finger or other grease got onto the rotors)
Level 2 – (A) Sand the pads – put the sandpaper down on a flat, hard shop bench and spray with alcohol. Pop out the pads and sand them down. Hold them very flat. Wipe clean with fresh alcohol and a clean towel. (B) Sand Rotors - both sides of the rotor surface a bit and clean them off as above.
Works every time.
(If they keep fouling, you might have a cracked or leaking piston.)