Check the caliper slides and make sure they are not frozen,same goes for wheel cylinders make sure the pistons are not frozen in the bore.also check the slides on the front spindle where the pads ride they sometimes form pits or groves and the pads get stuck and can no longer travel as they should.(if thats the case ten weld and grind to rectify).Also make sure your rear adjustment is up to snuff not to tight though.