Installing firewall mounted remote reservoirs for underfloor manual master cylinder on '48 Chevy truck. Currently using 2# residual pressure valves (front and rear) after the master cylinder. Should these be left in place or removed? I don't think they hurt anything being there. Anyone see a problem? If they gotta come out - now's the time. Thanks!
They might not be needed, but I think they're a good idea. They'll help keep the pads in closer contact with the rotors. They'll help give a more positive/firmer feel to the brake pedal.
Are they drums or disc? If they are disc then it won’t matter either way. Why would it keep the pads closer to the rotor? That is taken care of by the large cut seal in the caliper, has nothing to do with the residual valve Damnit! Lathe cut seal!! Sent from my iPhone using H.A.M.B.
The 2 lb disc brake residuals are only used when the master cylinder reservoir is lower than the calipers, to prevent fluid transfer from the calipers back to the master. Firewall-mounted masters or remote reservoirs eliminate the need for disc residuals.
Because there will be a constant two pounds of pressure behind the pucks when the brakes are not applied. They are needed when the MC is lower than the calipers to prevent fluid flowing back to the master cylinder...acting like a check valve.
Yes if it is lower, to keep the fluid from flowing back to the master, the pistons will not retract more without them. it will take more pedal travel to apply the brakes. Still has nothing to do with the distance of the pad from the rotor Sent from my iPhone using H.A.M.B.
The 2 lb residual should not overcome the caliper retraction seal, so the pads will not be any closer to the rotors. The residuals simply keep the lines full of fluid.
I'm a firm believer in the KISS principle, so the RPV's are coming out. Even though they aren't hurting anything, there's really no need to keep them, so one or two less components to worry about. Forgot to mention earlier that there's an inline proportioning valve - it will stay. Thanks for all the replies - now I have a better understanding of the reasoning behind using RPV's.
OK. Question....if their purpose is to simply act as a check valve to keep the lines full of fluid, then why do drum brakes require a 10# RV to do the same thing?
The drum brake residual, whether internal in the master cylinder or 10 lb external in-line, prevent air from entering past the wheel cylinder cups during fast release, because of the strong shoe return springs. Both 2 and 10 lb residuals do check fluid, but for different reasons.
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