Locked Up Disc Brakes

[JJWhite]

Hi,

I have a 1987 Acura Integra with around 141K on it... Last week I was doing about 80 on the freeway when my brakes locked on and I was forced to pull off the road. When taken to a mechanic I was told that my car had frozen front calipers. I had the front calipers and rotors replaced... I drove it home that night, no problem. BUT... the next day I drove about 4 miles down the road when it froze up again! After letting it cool off I took it home and replaced the master cylinder. Took it on a test drive and... locked again.

So, I've replaced the front rotors, calipers, and the master cylinder... I've flushed the fluid... and still, it keeps locking up.

The only things that I havn't done is replace the proportioning valve and the brake booster... people have told me that those expensive parts wouldn't be my problem.

Any helpful suggestions would be very much appreciated! I'm ready to find a cliff to drive this @#$! car off of!! :-)
JW

[superbluecivicsi]

i dont know what you mean by the brakes are locked. im assuming you mean the caliper pistons are not repressing leaving the front disc brakes still engaged on the rotors. you said the calipers have been replaced. Did your mechanic VISUALLY check to see if the brake lines are blocked/restricted? because if he knew the calipers are not engaging, he should of checked the lines.

anyways,

the porportioning valve concerns the rear brakes. dont worry about them. to check the brake booster, pump the brakes a few times with the engine off, then, hold the pedal down and start the engine. the pedal should go down slightly when you start the car.

next check if the brake booster is air tight. start the car and let it run for a minute. turn it off and pump the brakes a few times. the brakes should rise higher on the 2nd, 3rd, or 4th pump. turn the engine back on and hold down the brakes. turn it off with your foot still on the brakes. there should be no brake pedal movement.

i dont think its the brake booster though.