so we have this 56 wagon with a power front disc conversion that kept experiencing brake failure. everything just fine and then BAM... pedal to the floor. checked EVERYTHING 10 times. no leaks. no nothing. suspect master cylinder... right??? well two new masters later its still doing the same thing. scratching heads... turns out that when you turn the wheel full right, the banjo bolt on the caliper was hitting the upper bump stop and compressing the piston, pushing all the fluid back up into the master. so when you hit the brakes, the piston has to travel that extra distance which causes the pedal to drop to the floor. solution... grind the corners off of the upper bump stops and build up the turn stops so that they dont kiss under hard braking.
Reminds me of a left front caliper hang-up problem I had with my old Edorado. Had unknowingly changed routing of rubber brake hose (pulled it farther through bracket than previous) so that it had a kink in it with weight on the front trapping pressure. Wasn't obvious with front end jacked up. Only took one new caliper to figure it out.
The Jalopy Journal
