This does two things. A redesidual valve acts like a one-way or check valve to maintain brake system pressure to eliminate the problems of a spongy pedal. Several things affect line pressure. To test this cause, clamp off the rear hose so that the rear drums are disconnected from the rest of the brake system and test your pedal to see if … Once sufficient brake line pressure can be obtained, it’s important to set the front/rear balance so that braking forces are applied commensurate to the capabilities of the disc/caliper (or drum) and weight transfer so one doesn’t “lock up” before the other. If fluid is flowing properly out of both ports of the master cylinder (which we tested in step 2), but not making it through the valve, then most likely you will have to contact us to get a replacement valve. Master cylinder bore size and pedal ratio are the usual ways of changing it if needed. If a master cylinder with a 1 inch bore is replaced with a cylinder with a three-quarter inch or, the pressure and the brake lines will be higher when the same amount of brake pedal pressure is … A starting point would be 70% of the rear line pressure to the front brakes. Remember on an opposed piston disc brake it’s only the area … They're avalable at wood working, hardware stores and Sears. 4. If you use a drum brake master for disc brakes you would move an insufficient volume of fluid and the disc brakes would drag because of the residual valves. If the pressure is much lower at one or more wheels than it is up at the master cylinder, the problem is in the lines or at the calipers and drums. GENERATING BRAKING. The easiest way to compress the caliper pistons back to their full seated position is with a carpenters sliding C-clamp. residual pressure (RPV10) to counteract the spring tension in the drum system which tends to pull the shoes away from the drums. The amount of fluid that a drum brake master has to move is less than disc brake. Most brake setups require 1000-1500 psi to get good performance. This pressure keeps the drum brake balanced and keeps the shoes and the drums close together and gives you a higher and firmer pedal. A two pound residual valve is required whenever the master cylinder is lower than the calipers to prevent backflow of fluid … • Monitoring and control of brake and lube system • Monitoring of AC motor temperature and cooling pressure • Interface to hook load sensor (dead line) • Dynamic floor and crown saver system • Disc brake testing system • Disc brake burnishing system • Slip and cut function • … The residual valve holds a pressure keeping the shoes near the drums giving a higher firmer pedal. Without a ten pound residual pressure to the rear you will experience a spongy pedal. Also required a metering valve (PVM) to the front (the metering … You might tell us what you have for master cylinder, booster, and calipers. This valve are used in a drum brake system to prevent air from being ingested into the hydraulic system when you release the brake pedal.