Hi y'all. My 93 Explorer has a front caliper that is not stuck- but it is grabbing the rotor too tight. I was told the problem is the Master Cylinder but think it could be something else. There was this same tendency a year back when I changed the caliper. I don't have experience with the proportioning valve but wonder if it could be causing this. Any suggestions or advice on a troubleshooting protocol?

 

One thing you might try , when you feel the caliper is not releasing completely,open the bleeder on the caliper only enough to relieve any pressure. If the caliper lets go,you could have a questionable hose going to that caliper.