My front disk brakes are smooth and vibration free at low pedal pressure and high pedal pressure. But at medium pedal pressure they vibrate. (worse at about 45 mph).
I've had multiple rotors and the last set was premium Raybestos and I even had them trued. It hasn't fixed the problem. I tried changing pads and that hasn't fixed the problem. Caliper pins are lubricated and move freely. All caliper bolts and lugs nuts are torqued correctly. Caliper pistons also seem fine from what I can tell.
What other components can induce a harmonic brake vibration? The wheels are in balance and the hub bearings seem fine.
Can the combination of pad composition, rotor design, wheel and caliper produce a reasonant vibration with no one component being the culprit?
What else can be checked?
'97 Pontiac GTP