To get your clearances right try this. Remove pads, push pistons back as far as possible (use the box end of a 10mm wrench, avoiding the center post on the piston) reinstall pads. Remount the wheel. Insert a feeler gauge between rotor & pads on each side of rotor .015" x2. Or .016" & .014" If you dont have a feeler gauge a stip of thick paper ie: business card works well. Squeeze the lever several times, remove feeler gauges squeeze lever again check clearance. Should be ok.
Oh I forgot, loosen mounting bolts enough for caliper to move after remounting wheel then tighten them while squeezing brake lever with feeler gauges in place.
This may sound more complicated than it actually is, in my experience Hayes brakes are not too dificult work on.
Good luck.