Hy GMJager and guys, my comments on residual valves were aimed at the question being asked, I did not intend them to be a tutorial on all the possible permutations of brake systems. I never said that residual valves were only required for drum brake systems. As GMJager said if the master cylinder is mounted closer to the ground than the wheel cylinders or brake calipers then resisdual valves should be used to prevent fluid drain back to the master cylinder, 10 p.s.i. valves for drum brakes and 2 p.s.i. valves for disc brakes. I always try to answer the question being asked with only the information needed to answer that question, so as not to confuse the person asking the original question. Perhaps a Tech Tip on brakes would be a good idea. Hope that clarifies.
