Squealing brakes
08-26-17, 11:25 AM
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Squealing brakes
wondering what are chief causes of squealing with alum rims? could it be the caliper grip angle; old brake pads; grooved pitted rims; wrong type pads; other********************???? thank you kindly, rick
08-26-17, 11:29 AM
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You have listed everything I could come up with. If the pads aren't recent vintage, the cheapest solution is to replace the pads and clean the rims if they aren't clean already. You could try removing the pads and buffing them with sandpaper to remove any glaze but new pads with new rubber will probably work a lot better.
08-26-17, 11:29 AM
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It's a new safety device they include on all new bikes, an automatic horn to warn whoever you're slamming on the brakes to avoid.
Actually the squealing is very similar to that of a new chalk on a blackboard.
It's a harmonic effect caused by a grip-then-slip action. The most common cause is related to the sharp corner on the rear edge of the shoes, combined with lack of rigidity in the arms.
When you apply the brakes the movement of the rim pushes the shoe forward, causing the arm to twist so the heel digs in. This increases the force and twisting, until it reaches a critical point, at which it snaps back to the original position and the process repeats.
This is why people to in the shoes, so the heel doesn't touch until there's enough squeezing force to hold the shoes flat and resist the twisting action. Another cure it to break (dull) the rear corners, so there's a sort of ski tip, and they don't dig in as the shoe begins to twist (why dull chalk doesn't squeak).
Of course, oiling the rim would solve the problem, but I assume you prefer being able to stop.
Actually the squealing is very similar to that of a new chalk on a blackboard.
It's a harmonic effect caused by a grip-then-slip action. The most common cause is related to the sharp corner on the rear edge of the shoes, combined with lack of rigidity in the arms.
When you apply the brakes the movement of the rim pushes the shoe forward, causing the arm to twist so the heel digs in. This increases the force and twisting, until it reaches a critical point, at which it snaps back to the original position and the process repeats.
This is why people to in the shoes, so the heel doesn't touch until there's enough squeezing force to hold the shoes flat and resist the twisting action. Another cure it to break (dull) the rear corners, so there's a sort of ski tip, and they don't dig in as the shoe begins to twist (why dull chalk doesn't squeak).
Of course, oiling the rim would solve the problem, but I assume you prefer being able to stop.
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Last edited by FBinNY; 08-26-17 at 11:38 AM.
08-26-17, 02:59 PM
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If you took your question to the Mechanics Forum, I bet someone there would instruct you how to toe in your pads. Heck I could do it.
Loosen the bolt holding one side brake pad on. Place a penny between the back end of the brake pad and the rim and squeeze the brakes tight using the brake lever. Make sure the pad is properly aligned along the brake track and tighten the bolt. Retrieve the penny and repeat the process on the other side of the brake caliper on that wheel. Then adjust the brake caliper so the pads aren't touching the rim at their front end even though they are now closer at the front end than the rear. Repeat on the other wheel. Clean both rim brake tracks with alcohol and you are done.
Loosen the bolt holding one side brake pad on. Place a penny between the back end of the brake pad and the rim and squeeze the brakes tight using the brake lever. Make sure the pad is properly aligned along the brake track and tighten the bolt. Retrieve the penny and repeat the process on the other side of the brake caliper on that wheel. Then adjust the brake caliper so the pads aren't touching the rim at their front end even though they are now closer at the front end than the rear. Repeat on the other wheel. Clean both rim brake tracks with alcohol and you are done.
08-26-17, 03:15 PM
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08-27-17, 11:52 AM
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08-27-17, 11:59 AM
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08-28-17, 03:12 PM
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Go to 3:40 and you will see how to set the toe of your pads. This should help.
-Shin
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08-28-17, 03:59 PM
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Oils and some cleaners leave residues that can make your brakes squeal, rim or disc. If you wait long enough, they might eventually clean themselves and be silent. Operative word is "might".
If you are in a hurry, you might try some rubbing alcohol or ethanol on a rag and wipe the rims and brake pads.
If you are in a hurry, you might try some rubbing alcohol or ethanol on a rag and wipe the rims and brake pads.
