Residual Pressure Valve

[mobileortho]

I know it's recommended that those with the MC mounted on the frame rail should use a residual pressure valve to help eliminate pedal travel, but I have the same issue & mine is mounted on the firewall. Shouldn't that work in my case as well? Looking at getting the 2lb valve since I have disc's on the back.

[lazypineapple]

my MC is on the frame, and I do not use a front RPV.
Disc/Drum.
i do use one on the rear.

it easy to tell if you DONOT need them. your brake will lock or drag really bad.

frame mount MC shouldn't need RPVs

[Speedbumpauto]

RPV's can be used to maintain some pressure in the system regardless of where the MC is mounted. Gravity tends to work in favor of firewall mounted units as they are higher than the wheel cylinders but having a small amount of pressure in the lines can give better pedal feel + 2 pounds should not activate the caliper pistons nor should it keep the square sealing ring of the caliper from relaxing which is what gives rotor space on single piston units. on frame mount MC's I consider them a must. I had one go bad(2lb.) on the front of my street rod and if the car sat for a week or more, the brake pedal had to be pumped once or twice to re-establish the proper pedal feel. There were zero leaks, a small amount of the fluid simply migrated back to the MC. A new RP valve fixed it. MC's on older vehicles, even firewall mounted, had RP valves built into the MC right behind the brake line fittings. That's why you never saw them in the lines.