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Proportioning Valves 101

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When it comes to your car’s braking system, several components come into play. Here at Pirate Jack Hot Rod Restoration, we offer quality replacement auto parts for your old-school hotrod. We strive to bring you all of the tools and equipment needed to optimize performance vehicles. One such product we sell is the brake proportional valve. This performance part is vital to your car’s operation, yet often it can be overlooked. The general public’s knowledge may be limited on specialty products, so today we’ll cover the common questions that follow this tool.

What Is It?

A proportion valve is a valve system that sits between your master cylinder and the connection to your rear brakes. The body consists of a tube with with a spring that keeps the valve open. When a direct amount of pressure is applied, the pressure from the master cylinder moves the piston within the proportioning valve, reducing the amount of fluid applied on the back end to the rear brakes. In essence, this equipment changes the braking system with changeable pressure levels to the brakes. Installing this part adds control and stability to your vehicle when dealing with panic stops.

Why Use It?

In general, a proportioning valve is useful for all vehicles for proper emergency braking. The added engine weight to the front of vehicles equates to heavier braking in the front and less weight and stress in the back. If the brakes were to be applied equally, an excessive amount of locking up would occur in the rear brakes. Typically, proportional valves are used for vehicles with front disc and rear drum brakes. Due to the design and surface contact differences between these two systems, a proportional valve is necessary. Otherwise, your disc drums will be making contact and slowing the vehicle down long before the drum brakes come into play. When performing a sudden, emergency stop, brakes without proportional help will lock up, likely causing a crash.


Proportioning valves are essential for proper performance in disc/drum brake vehicles. Savvy drivers can set and tweak the valve itself to allow for a more customizable braking experience. When tooling with your favorite hot rod, the brake equation definitely comes into play. Be mindful that these valves are only utilized during quick, hard braking. Will it help? Yes. Will it last? Definitely! Pirate Jack has all of the tools and equipment needed to optimize your performance vehicle. Contact us today to see how we can help improve your driving experience!