I'm pulling my hair out with my 68 Amazon's brakes. This one's been dormant for who knows how long, and is slowly being revived one system at a time. It's not my first brake job by any means, but the first one on an Amazon.

The brakes got rebuilt calipers, IPD stainless hoses, and got the old fluid pushed out before connecting to the freshly rebuilt calipers -- let's not contaminate them. First signs of trouble were that after bleeding, the first pump of the pedal was mushy, but the second was rock solid, feeling normal.

During the test run down the street and back, it was quickly apparent that the brakes were not releasing. Didn't pull to one side or the other when I let go of the steering. Mind you this was only at 10-15 mph, in first gear. The brakes wouldn't let the engine pull in second. By the time I got back to my starting point, 1st gear wasn't low enough (but reverse was!). Loosen the bleeder on the caliper, get a shot of fluid out, indicative of pressure in the lines.

Would this point to a failure of a check valve or something in the master cylinder or the brake booster? I readily admit the whole external booster concept has me flummoxed. I've so far worked exclusively on cars with the booster on the other side of the master cylinder. What are the failure modes of the booster?

Thanks!
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88 740ti 260k and counting....