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  1. #1
    TC3
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    ... and if we just ... another tip to get rid of squealing noise

    I got a set of mono minis a while ago.
    The rear one works fine, but the front one was my major headache.
    It was squealing like a dying pig, that you can hear it from half of a mile away...
    I tried every tips in FAQ, wiped the pads, rotors with alcohol, tighten the spokes, hubs...
    But it didn't seem to work in my case.
    I decided give it another try before I buy a facing tool.
    I removed the brake pads and pushed the piston as far back as possible.
    Then, put the pads back.
    Took my bike out for a ride and I found.....
    It works!!
    I was in tears... kidding
    Anyway, hope you find this useful.

  2. #2
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    Ah, the dreaded brake drag. Dirt accumulates on the pistons in the unswept area. (Where it doesn't get wiped clean by the seal every time the brake's applied & released.) The more it builds up, the more it impedes the piston's ability to pull back into the caliper when you're off the brakes. Any time you replace pads, be sure to clean the pistons before you push 'em back farther into the calipers. And apparently it's a good thing to clean 'em once in a while, regardless.

  3. #3
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    How do you clean pistons? It's probably a dum question!

    I've never played in there, changed pads but that's about it.

    How do you clean the pistons? Do you pull on them and at a certain point the fall in your hand? Does the oil spill from behind the pistons? What do you use to do the clean up, alcool?

    Thanks. Sorry if this is pretty basic for a question.


    Quote Originally Posted by Wheezer
    Ah, the dreaded brake drag. Dirt accumulates on the pistons in the unswept area. (Where it doesn't get wiped clean by the seal every time the brake's applied & released.) The more it builds up, the more it impedes the piston's ability to pull back into the caliper when you're off the brakes. Any time you replace pads, be sure to clean the pistons before you push 'em back farther into the calipers. And apparently it's a good thing to clean 'em once in a while, regardless.

  4. #4
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    Idea!

    Quote Originally Posted by BanzaiRider
    I've never played in there, changed pads but that's about it.

    How do you clean the pistons? Do you pull on them and at a certain point the fall in your hand? Does the oil spill from behind the pistons? What do you use to do the clean up, alcool?

    Thanks. Sorry if this is pretty basic for a question.
    NOTE: I've done a lot of work on motorcycles, so I'm assuming that bicycle systems are simlar. ...Here goes:

    Think of your brakes like a water balloon. You squeeze here, something bulges somewhere else. Basically brakes are a rigid system, with only one point that can bulge: the pistons move in the calipers. When you let off the lever, the return spring creates a "vacuum" in the master cylinder that sucks the pistons back into the caliper. There are little round seals (square-edged o-rings) that seal the gap between the caliper and piston. This "wiped" area has to be nice and clean for the pads to move smoothly. --Especially for them to return correctly.

    As pads wear, you have to move the pistons farther and farther out. As this occurs, the outer part of the pistons don't get wiped clean any more, and a band of crud builds up. If, for whaever reason, this piston gets pushed back into caliper far enough that the dirty area that has to move past the seals, either the pads don't want to retract all the way, causing brake drag, or they bind up on the ring of crud and don't extend smoothly. (This can happen because of a high-speed wobble, a bent rotor, wheel flex, etc., and WILL happen when you put in new pads or rotors.)

    So, clean is good.

    Remove your pads, and press the levers just enough to extend the pads a LITTLE bit; just enough to expose the crud, NOT enough to pop the pistons out of the caliper! (Bleeding is a such a hassle!) Do one piston at a time if you have Hopes, or somesuch.

    If you can just wipe the crud off without solvent, cool. Beware that those little seals may react chemically with whatever cleaner you use, and could swell or turn to gummy mush with the wrong solvent. The safest bet is to use the same stuff on the outside of the seals as lives inside the calipers (mineral oil or hydraulic fluid). Use a Q-Tip or a toothbrush to scrub 'em clean. Rinse with water (and perhaps a mild cleaner like isopropyl alcohol if you're afraid you might have oil in the nooks & crannies that could contaminate your pads.)

    Voila!

  5. #5
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    I'm hooked on the magic sauce, you know the .99 can of brake cleaner that has every know solvent expelled in suspension. I just hold a rag behind and catch the crap, wow, its a time saver. Also on the cassette its a quick clean. Guess I'm a polluter

  6. #6
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    Quote Originally Posted by Brown_Teeth
    I'm hooked on the magic sauce, you know the .99 can of brake cleaner that has every know solvent expelled in suspension. I just hold a rag behind and catch the crap, wow, its a time saver. Also on the cassette its a quick clean. Guess I'm a polluter
    Yeah, that's what I do "most of the time." But when I replace pads, or when brakes start dragging (squealing or wearing too fast), it's time to go whole hog.

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