Stovebolt.com Forums The Shop Area The HiPo Shop Brake questions: modified '57 3600

That was my thoughts... I have never seen one mounted in the rear brake line. I was just assuming (probably wrong) that it had work prior to this.

A RPV is designed to maintain a slight amount of pressure in the brake lines at all times. On rear drum brakes with strong return springs that retract the shoes when the brake pedal is released, and relatively small diameter wheel cylinder cups, a 10 PSI valve is needed to keep the wheel cylinder cups expanded against the walls of the cylinder to avoid air getting past the cups and a spongy pedal developing. Since the only thing that tries to retract a disc brake caliper piston is the distortion of the square O ring as the piston pushes against the pad, and the large diameter of the piston, a 2 pound valve is all that can be used without causing the disc brake to drag. Most of the hydraulic brake light switches I've seen were either located at the master cylinder outlet fitting on single-line brake systems, or in the rear brake line like 1950's MOPAR vehicles. Virtually all auto manufacturers went to pedal-mounted brake switches in the late 1950's or early 60's, mostly because of the proximity to the steering column, and the necessity to incorporate a discriminator circuit to the brake lights on vehicles factory equipped with turn signals.
Jerry

It just dawned on me that I didn't let everyone know what finally fixed my problem with the brake lights. The solution was simple: I replaced the brake light pressure switch. Apparently the old switch had gone bad and wasn't shutting off completely when the brakes were released. Thanks to everyone for the help.

Sometimes we make the BIGGEST problems out of the smallest solutions. My Auto Shop teacher was a firm believer in the " KISS" method (Keep It Simple Stupid), from time to time I have to relearn that. Glad you worked it out.