I just had a thought. The current set up consists of a 1970’s Corvette style master cylinder. I’ve seen lots of cars and trucks use these when they upgrade to disc brakes. The MC piston has a place for the pedal pushrod for applications when a booster is not used. With a booster, a short piece of steel rod is inserted in the back of the MC piston to fill that hole and provide a place for the booster pushrod to push on to move the MC piston. If the steel rod is too long, then the master cylinder would never be able to fully retract to the home position but on the bench, the MC would work normally during the bench bleed. What do you think? You can see the steel rod in question in this picture. Am I crazy?
