Disc brake squeal
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  1. #1
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    Disc brake squeal

    My front Shimano 105 brake squeals (the back brake is quiet), especially on long technical downhills where I have to do a lot of braking. I think it's heat related, and try to use the brakes intermittently to allow them to cool. Any strategies to eliminate the squeal (more like a loud howl)? I've cleaned the rotor with alcohol (didn't work). Maybe removing and sanding the pads might work, or changing out the pads to another brand (like Swiss Stop)

  2. #2
    tlg
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    Pads are like sponges. If they've been contaminated with oil/grease sanding them will do no good. You could try soaking/cleaning them real good with alcohol or mineral spirits.

    Best bet is to just get new pads. If the squeal goes away, you know it was a problem with your pads. If the squeal is still there, there's another problem, and you've got a spare set of pads. You'll need them eventually and they don't spoil.
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  3. #3
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    Quote Originally Posted by tlg View Post
    Pads are like sponges. If they've been contaminated with oil/grease sanding them will do no good. You could try soaking/cleaning them real good with alcohol or mineral spirits.

    Best bet is to just get new pads. If the squeal goes away, you know it was a problem with your pads. If the squeal is still there, there's another problem, and you've got a spare set of pads. You'll need them eventually and they don't spoil.
    Clean the rotors with alcohol as well.

  4. #4
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    Quote Originally Posted by Steve B. View Post
    Clean the rotors with alcohol as well.
    Quote Originally Posted by mfdemicco View Post
    I've cleaned the rotor with alcohol (didn't work).
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  5. #5
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    Quote Originally Posted by tlg View Post
    Pads are like sponges. If they've been contaminated with oil/grease sanding them will do no good. You could try soaking/cleaning them real good with alcohol or mineral spirits.

    Best bet is to just get new pads. If the squeal goes away, you know it was a problem with your pads. If the squeal is still there, there's another problem, and you've got a spare set of pads. You'll need them eventually and they don't spoil.
    I'll try swapping pads front to rear, since the rear pads don't squeal.

  6. #6
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    And don't forget to perform a brake bedding in procedure. It goes along way to help with improved braking and quiet brakes.

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  7. #7
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    disc brakes have been squealing for the last 2 decades in mtb world.
    You should embrace the squealing and learn to live with it.

    And becareful if you're swapping pads fron and rear. Last thing you want to do is to contaminate the rear pads (clean) with the possibly dirty front rotor, and now your rear brake would squeal too

  8. #8
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    What pads are you using? I have had problems with squealing that went away when I switched to metallic pads - very quiet when dry, they do make lots of noise wet.
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  9. #9
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    Has anybody tried borrowing from the automotive world? Over at any auto parts store, you can buy anti-squeal lube to put on the backing plate of your disc pad, or even vibration-absorbing backing spacers. Most mechanics know that softer pad materials don't squeal as much, but also give lower performance. There used to be pads which were made from coral that were guaranteed to not squeal (but gave sucky braking, and wore out very fast).
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  10. #10
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    Quote Originally Posted by aclinjury View Post
    And becareful if you're swapping pads fron and rear. Last thing you want to do is to contaminate the rear pads (clean) with the possibly dirty front rotor, and now your rear brake would squeal too
    Not if he cleaned the rotor with alcohol.

    I would replace the pads, spread the calipers and set the brakes again.
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  11. #11
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    Quote Originally Posted by No Time Toulouse View Post
    Has anybody tried borrowing from the automotive world? Over at any auto parts store, you can buy anti-squeal lube to put on the backing plate of your disc pad, or even vibration-absorbing backing spacers. Most mechanics know that softer pad materials don't squeal as much, but also give lower performance. There used to be pads which were made from coral that were guaranteed to not squeal (but gave sucky braking, and wore out very fast).
    I used to be an auto mechanic so I've tried the disc brake quiet stuff on brake pads years ago. Never work IME.

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  12. #12
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    Assuming that your pads are not contaminated with oil, here's something you try

    Part 1: prepping rotor and pads

    1. remove the rotor from the wheel.
    2. remove the pads from the caliper
    3. use 150-200 grit sandpapers to rough up both sides of the rotor to the point that that the rotor is not shiny looking anymore (ie., rotor should have a "brushed" surface finish after this procedure). Do the same to the pads.
    4. reinstall rotor and pads


    Part 2: bedding in rotor and pads

    1. get the bike to about 15 mph, then very gently and softly pull the brake lever for about 1-2 seconds. The bike should still be moving and should never come to a complete stop. Do this 5 times.

    2. get the bike to higher speed, say 22+ mph, and brake real hard (like you would in a descent), each brake pull should be about less than 1 second, but making sure the bike is not allowed to come to a complete stop. Do this 10 times.

    this shoud bed in the pads and rotor good.

  13. #13
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    I've had disc brakes since 1999. I've tried lots of things to unsqueal squealing pads... including setting them on fire. Seriously - soak in alcohol, light, let it burn off, extinguish. It's supposed to pull out whatever's contaminating the pads. Works about as well as drinking a special shake to detox the body. The only trick I've found that works is buying new pads. Had good luck with that technique ;-)

  14. #14
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    Rotors should never need to be sanded. If they were designed to work that way, they would come that way. Isopropyl Alcohol and a clean rag is all that is required to prep a rotor. Sanding pads will only remove contamination from the surface, contamination of pads almost always runs deep. Torching pads results in loss of braking power.

    Buy new pads, clean rotor with alcohol, install new pads.

  15. #15
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    I've had rotors that I couldn't clean w/ alcohol and I don't usually have brakekleen in the shop...probably should. Sanding will remove that pad material and won't hurt anything.
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  16. #16
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    Sanding the rotors is a good way to clean up glazing that occurs when a brake bed in procedure isn't used.

    I had a squealing rear brake on my MTB. Rotor and pads were glazed. Didn't perform a brake ped in procedure correctly. Replaced the pads, sanded and cleaned the rotor with alcohol. Performed a proper bed in procedure. Squeal gone.

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    Quote Originally Posted by JoeDaddio

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  17. #17
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    I swapped the pads, front to back. Helped a bit but howl still occurs on the front (not rear) on downhills with lots of braking. I'm wondering if I should try an Ice-tech rotor, since they run at lower temperature and this problem occurs when the brakes get hot. Otherwise I'm thinking of Swiss Stop pads instead of the Shimano resin.

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