Proportioning Valve

A drum brake master will not cause a soft pedal. A drum master has residual valves in each outlet, as opposed to a disk master which only has the residual valve in the drum outlet. A residual valve will "hold out" the pistons a bit causing them to drag. You can easily defeat them by simply running a nail in through the valve rubber with the fitting disconnected. To actually remove them, you need a very small sheet metal screw which will screw into the brass seat, then yank it out with a claw hammer and remove the valve rubber and spring.