Its now driving me insane… i’ve tried all the old tricks, i.e. clean rotors, new pads, copper grease on the back of the pad etc etc etc…

Anyone know why they do this and what… if … there’s a fix???

Cheers
JB

Change the pads

Do you mean squealing when braking or a permanent squeal?

Mine were making a permanent squeal even with brakes off. I pumped out the pistons and cleaned them off with GT85 which cures the problem…for a few rides at least. They are 5 odd years old though and have never had new seals.

MM

Done that… couple of times, might be of for a couple of rides, but then they start squealing again!

They only squeal when breaking. Must admit i’ve never cleaned the pistons or changed the seals.

Could be build up of brake dust then. Get a proper aerosol brake cleaner, whip out the pads, and give them a proper clean, also try a little DOT around the piston seals, they could be coming out unevenly

Do they say "Hope" on em? Does it sound like you’re being attacked by a flock of geese when you brake at speed? Its just the way I think.

my M4s only sqeual when theyre really hot or when i’ve just washed the bike. out of interest what pads have you got in them?

all the above is a good idea though, giving the pistons a good clean with some brake parts cleaner and some silicone spray is also good for the seals.

i actually quite like the howl of the M4s when hot on sintered pads though!

my m4s squeal when cold, and I also found swisstops really noisey all the time, but Hope Sintered are fine once warmed up. Maybe use some silicon spray (buy it from engineering supplies, also CRC sells Stendec version) on the pistons once cleaned to stop them sticking and make sure the caliper is centred properly. Are they bled properly? Are you using Post mount or IS mount? IS mounts can be bad news unles you face the mounting points properly. A good LBS should carry kit to do that.

mine are IS and i spent ages spacing them up with hope shims to get the alignment right, its a horrible fiddly job i must say!

If you are using sintered pads they will squeal unless they get really hot! For a quieter life, use organic pads.

That’s funny cos my M4’s never squeal. Dunno why though.

Mounts need facing?