do you still need the residual pressure valve for the rear drums when you are running a proportioning/combination valve for disc/drums. I thought that the proportioning/combination valve did both?
Brian
after reading the e-bay spot it says that with the master cylinder as low as the brakes you should run the pressure valves.
then I found this at another spot about the job of the proportioning valves
This valve decreases the pressure to the rear, preventing lock up. Metering: Metering is used in the front disk brake portion in the disc/drum system to delay application of the front discs allowing the slower reacting drum brakes to catch up. This provides rear stability on wet surfaces and helps prevent front pad wear. There is no metering function with the disc/disc setup.
Residual Pressure: Drum Brakes require residual pressure of 10 lbs. to be held in the line. This pressure keeps the brake shoes close to the drums giving you a more firm pedal feel. The disc/disc setup does not require this pressure.