Proportioning Valve Basics – Web Exclusive

Choose the right braking valve.

When running any type of disc brake system on a car you need to remember which proportioning valve you should run. This is very important because the job of a proportioning valve is to distribute the right pressure to the calipers. The proportioning valve reduces the pressure to the rear brakes. Regardless of what type of brakes a car has, the rear brakes require less force than the front brakes.

The amount of brake force that can be applied to a wheel without locking up depends on the amount of weight on the wheel. More weight means more brake force can be applied. If you have ever slammed on your brakes, you know that an abrupt stop makes your car lean forward. The front gets lower and the back gets higher. This is because a lot of weight is transferred to the front of the car when you stop. Also, most cars have more weight over the front wheels to start with because that is where the engine is located.

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 works as a resistor and only lets a certain amount of the pressure through to the rear wheels so that the front wheels apply more braking force. If the proportioning valves were set to 70 percent and the brake pressure set at a 1,000 pounds per square inch (psi) for the front brakes, the rear brakes would get 700 psi.

In today’s aftermarket world the brake guys are using the two different proportioning valves that are identical from the out side but internally they are completely different. Now follow along as we help you figure out which valve is the right one for you.

1. Today you can buy your proportioning valve chrome plated to match your engine compartment. This one that we are showing you is set up for 4-disc brakes.

2. This proportioning valve looks similar to the first one we showed you but this one is set up for disc in the front and drums in the rear.

3. When running rear drum brakes, the pressure involved is different. This built in check valve located in the front will help tell the difference between the two most common proportioning valves. This one is for drum brakes in the rear.

4. All smooth is made for 4-disc brakes.

5. If you ever have to make hard lines in stainless, these AN #3’s will help you to do a single flare on the tubing. This process can be done to both style proportioning valves.