what is a combination valve
A disc/drum combination valve (PV2) is the easiest way to properly balance your braking system. The combination valve is two valves in one. It provides metering to the front which prevents nose dive and proportioning to the rear which prevents rear wheel lock up.We also recommend the addition of a 10 lb residual valve (RPV10) to the rear drum brakes.he best way to plumb a disc/drum system when the master is under the floor is with a combination valve (PV2) and then a 2 pound residual valve (RPV2) to the front which is needed to prevent fluid from flowing back from the calipers into the master.