| The squeal can sometimes come from the interface between the side/edge of the back of the pad and caliper, so it can help to have a little dab of copper grease there. Cleaning will always help because it is dust/dirt between the surfaces that normally squeals, but cleaning only works until the dust builds up again.
One other thing that can sometimes cause a squeal is the leading edge of the pad where it touches the disc. Sometimes if that leading edge is very square it causes a squeal, which can be solved by filing an angle onto the leading edge. | 
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