Ok...

My brakes grab. But only after driving 15 miles.

When they grab, my brake pedal is as hard as a rock. If I turn off the car and let it sit 10 minutes. They wont grab again until I drive another 15 miles.

My car has:

New front calipers
New master cylinder
New rear wheel cylinders and shoes
Thoroughly inspected brake lines.
100% fresh brake fluid.
Turned rotors.


I'm thinking I got a faulty master cylinder. Could a master cylinder do this? Proportioning valve? I don't know.

I'm beginning to want to light this car on fire.

 

Brake booster is going bad. After driving for a while do the brakes tend to lock up and ytou cant go anywhere?

 

I got the same problem changed the same things,still have the problem,I changed brake booster to.The one thing i did do is an Si rear disc setup,but problem was there before I did this.Now my new brake booster is for STD model,but the master cyl. is for an Si.I don't think this matter.I think it could be a vac.problem with the intake.I don't know swaping motor anyway I'll find out then. If anyone has an answer to this problem I would love to hear it.Thanx