[Akimbeau]

Originally Posted by jhv48

Next question. Did you buy the car from someone or are you the first owner? When you got the car, did the brakes work correctly? What type of brake fluid did it have in it? Most come with DOT 3 or 4, though some have 5.1. If the car was setup for racing, it might have used DOT 5 fluid, a silicone based fluid that works better in higher temps but doesn't hold water in suspension.
DOT 3, 4 and 5.1 are polyethylene glycol based. DOT 5 is silicone-based and does not mix with the polyethylene glycol based fluids.

If the car had either synthetic or silicone and someone accidentally mixed the two, the seals in both the calipers and the master cylinder would slowly be destroyed and need rebuilding. To boot, in order to change from one type of brake fluid to the other requires a thorough flushing of all lines and cylinders before adding the new fluid.

Seems like you've tried everything else. This is the only thing left.

The brakes have been totally rebuilt and all fluid has been changed. I have always used Dot 4 synthetic.