Gyrobob
Serious Thumper
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Posers ain't motorcyclists
Posts: 2571
Newnan, GA
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Brake squeal is something that can be controlled rather cheaply.
The squealing is from a resonance of high frequency vibrations in the pads/calipers when they contact the rotor. Because of the job the disc brake has to do, this squeal is common, even though the manufacturers' engineers probably tried hard to prevent it.
There are lots of ways to fix this. Replacing pads with lots of material left on them is not a sensible option,… a waste of money.
The idea is to change the resonance of the parts that vibrate, thereby pushing the resonance out of the range that creates a squeal. Here are some ways:
-- Use the lube typically supplied with replacement pads. This is a high-heat lube that goes between the pads and the piston that changes the resonance frequency. Use sparingly.
-- Use that same lube on all the parts that support the caliper that allow the caliper to move back and forth. Clean everything really well first, and, again, use sparingly.
-- I hear folks like Loctite, Permatex, CRC, etc., have sprays/pastes designed to fix squeals, too. Apply to the back of the pad, methinks.
-- Sometimes the pads, or even the rotors, can acquire a glaze that tends to make a squeal. Lightly scouring one or both surfaces can help here. Use 400 grit sandpaper (wet), or rubbing compound, steel wool, chore girl, comet cleanser, etc. You don’t want any scratches, just a satin finish.
-- Chamfer the edges of the pads just a little, maybe a 1/16" wide chamfer.
--- Chamfering the leading edge of the pad is sufficient.
--- This alters how the leading edge of the pad tries to "dig in" to the rotor, changing the resonance frequency.
--- The squeal may come back in a few thousand miles as the pads wear down. Just chamfer it again.
-- Clean all the surfaces completely, then put a very thin layer of RTV on the back of the pad where it contacts the piston in the caliper. Also put a very thin layer on the surface of the piston that contacts the pad. Let it dry for a few hours before reassembly.
--- Very thin layer = Put a little on your finger, rub it on the surface, then wipe just about all of it off with a clean finger.
--- You don’t want any actual cushion here,…. that will make the brakes feel spongy. You want only enough to change the resonance of these two mating surfaces,.. just residue, not an actual layer.
--- Use something with a high heat capability. Normal RTV works,.. hi-temp RTV might be better. It's cheap.
-- Cut out a piece of coke can metal shaped like the back of the disc brake pad, and insert that piece between the pad and the piston. That metal is thin but is pretty tough stuff -- I use it for shims when aligning gyrocopter rotors. Sounds goofy, but it does change/negate the resonances, so it can eliminate the squeal.
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