Tandem master cylinder (1 Viewer)

Aug 10, 2018
Not mine, but a good explanation of why you NEED a proportioning valve:

"A Proportioning valve is required on vehicles that have disc brakes on the front wheels and drum brakes on the rear wheels. Disc brake pads are normally in contact with the disc, while the drum brake shoes are normally not in contact with the drum. If the pressure was not proportioned the disc brakes would engage before the drum brakes when you depress the brake pedal.

The Proportioning valve compensates for this, allowing the drum brakes to engage first before the disc brakes. The Proportioning valve does not allow any pressure to the disc brakes until a pre-determined pressure has been reached. The pre-determined pressure is low when compared to the maximum pressure in the braking system, this allows the drum brakes to engage before the disc brakes engage. Having the rear brakes engage first provides the control and stability needed to stop your vehicle safety.

The proportioning valve reduces the pressure to the rear brakes. Whichever type of brakes your vehicle has, the rear brakes require less pressure than the front brakes.

If equal braking force were applied to all four wheels during a stop, the rear wheels would lock-up before the front wheels. The proportioning valve only lets a portion of the amount of pressure to the rear wheels thus preventing rear wheel lock-up."
Thank you.
I just got a two reservoir MC. Se attached photo. Do they sell proportioning valves that can be installed with the MC I purchased?

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