Sometimes on the old cars the master will have trash deep in bores. When you change pads and depress the pedal to the floor the trash will cut the seal on the piston. :-(
Some of the old water cooled VW's with ATE master would roll the seals over when pressing the calipers back, I got into the habit a long time ago of slipping a peice of silcone vacum line on the bleeder and then opening the bleeder and pushing the caliper back, and not depressing the pedal to the floor bringing the caliper pistons back out tot he new pads.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.