You guys are right about the smaller m/c, I forgot about Pascal's law on hydraulics when I posted. The rsidual valves are usually contained in tha proportioning valve assembly, the return
spring on the caliper is only for the parking brake. If you use GM rear calipers make sure that you use the parking brake regularly, this is how they are adjusted and it also keeps the piston from sticking in the bore. I've seen and
replaced many of these because of that reason.
