this is driving me mad, not rode the bike for a while. cleaned the rotors. they squeal like crazy but seem to only do it once hot (hard pressure) one they are hot they squeak with every tiny touch of the lever. wondering if some fluids leaked out of the calliper?
Check the centreing of the rotor between pads. Even if they look centred and have been done by slackening caliper, applying brakes then tightening, it can be out. If one pad hits the rotor first can bend the rotor slightly and cause squealing.
Also glazed pads can squeal. Remove pads and sand lightly with fine wet and dry. Then replace.
this was driving me mad,
replaced the pads with new.
cleaned with disc cleaner
rubbed discs down with sand paper.
the squeal is a lot better but it does sill happen. but it only seems to happen once the disc is hot (after some good breaking)
now what
As above probably an alignment issue, If everything looks ok are the pistons working smoothly and contacting the rotor evenly? If all else fails - a friend had some squealing avids that nothing would cure. On the advice of an lbs mechanic he superglued a tiny lead fishing weight to the calliper. A bodge but somehow it worked a treat.
It'll likely be alignment as nige up there has said.. Also make sure both pistols move equally meeting the disc centrally in the caliper. If one pad is moving further than the other hold it back whilst actuating the brake to level them out.
I've played with the alignment (they seem ok and sit in the middle of the pads without binding)
how do I make sure each piston moves the same? (take pads out) what if they dont?
Watch how they move when you pull the lever, Does one pad hit the disc before the other? If so, as I said up there.
if in doubt pads out pump pistons out rub a bit of brake fluid around pistons/seals push them in n out a couple times then pads back in check centering .