COMBINATION VALVE A combination valve is incorporated into the brake system. It performs three functions; a balance function, a metering function, and a warning switch.
METERING VALVE FUNCTION (Spring and poppet on left side of Combination Valve) The metering section of the combination valve operates to \'hold off\' hydraulic flow (pressure) until about 130 psi has been built up in the system before applying the front brakes. The pressure then blends to a full line pressure at approximately 400-600 psi line pressure. There is no flow restriction when the brakes are released.
BALANCE FUNCTION OR WARNING SWITCH (Piston in middle of Combination Valve) The fluid from the front and rear systems is separated by a hydraulically balanced sealed piston. A spring loaded plunger rides in a groove in the switch piston. Any pressure differential sufficient to overcome the plunger spring and friction causes a shift of the piston in the direction of reduced pressure, causing the switch plunger to ride up and out of its groove and the switch to make contact and light the warning light (100-300 psi differential is required).
In addition, this piston is designed to hydraulically recenter itself once the pressure balance is restored (leak is fixed).
The data is concise. I installed a p-valve over a year ago and its leaking from the metering valve. Light is constantly on. Both front caliper bleeders are rusted shut. Please call me 717 576-6806 Henry
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