i got this car about 3 months ago. i've been having issues with the brakes. the pedal would sink to the floor. changed master and i get a better pedal feel. flash forward a week. car starts locking up driving home. get home take it apart see calipers need love and so do pads. i change everything from the caliber to the rotor. test drive it the pedal feels really stiff. but car feels smooth. get home park the car to cheak things and go to do the long distance test drive and it started doing it again, but this time i can tell its the passanger side this time. i have no idea where to go from here.

 

Is there ANY possible way that the system (brake fluid) could be contaminated with petroleum? Unfortunately that is what it sounds like is going on...

 

I agree it sounds like you need to flush the system.

 

that im awear of no. i have went thru a fool bottle of brake fuild thu the whole car. so i should drain all the fuild again?

 

Did you make sure to bench bleed the master when you replaced it? Is the seal in the master bloated? Maybe your pushrod needs adjusting...

 

Well you would know (by now anyway) if it is contaminated. The seal on the master cylinder would be swelled up beyond recognition. Basically that's what happens to any rubber component in a brake system when petroleum is present... Thus leading up to your locking up problem and your stiff pedal.. But then again the car is not in front of me so it is hard to diagnose .. I would try flushing out the system again, and check the push rod in the booster it could be out of adjustment.. You say you just recently bought the car was it like this when you bought it? Or has this problem shown up since then?