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Upgraded brakes are necessary when running a high-performance application, whether on-road or off. Just like switching out brake pads, rotors, and calipers is on the list for replacement, so should the proportioning valve. That’s especially true when changing the brakes over from drum to disc.
At JEGS, you’ll find that Wilwood brakes are a go-to for vehicle owners who demand the best, and an adjustable proportioning valve is one of the components they offer. Learn more about what the proportioning valve does, why an upgrade is crucial, and the steps for adjusting the Wilwood proportioning valve you’ve chosen.
Understanding The Proportioning Valve
How does a proportioning valve work, you ask? On a normal street vehicle, the proportioning valve is typically mounted directly under the master cylinder, balancing the brake pressure going to the front and rear brakes so your vehicle will stop well. It’s also called a combination valve.
Inside the valve are pistons with different surface areas for the front and rear. When pressure is equally applied to the pistons, they apply braking force at different rates, which is why the braking effort is different at the front and rear.
It’s necessary because the rear brakes don’t – and shouldn’t – apply as much stopping power as the fronts on most applications. If they did, they’d lock up easier and potentially cause you to lose control. But it’s not a linear application, contrary to what most people think. Once you reach a specific pressure point, the valve proportionally decreases the pressure to the rear brakes.
For high-performance applications, fine-tuning the brake pressure might be what you need to cut a few more seconds off your car’s lap time. It might also be essential to increase or reduce the brake force distribution to the rear so it doesn’t feel like you’ve dropped an anchor as soon as you touch the brake pedal.
Adjusting Your Wilwood Proportioning Valve
Ideally, the rear brakes should provide around 30% of the stopping power for street applications. For performance like drifting, you might want them to be way touchier so you can throw the back end around on turns. At the end of the day, when you have an adjustable proportioning valve, how you set it up is all up to you and your preferences.
Remember that you’re in control of the brake pressure with a Wilwood proportioning valve, but you still need to set it up to brake safely. Let’s walk you through adjusting a brake proportioning valve from this well-known, trusted manufacturer.
Knob Style Valve
The initial adjustment for knob-style valves is straightforward and begins with basic suggestions. Find an empty parking lot and recruit an observer from outside the car:
- Inflate the tires to your normal operating pressures
- Declutter your car and have the fuel tank around half-full
- No one should be riding in the car, not even shotgun
- With the valve installed, accelerate to 30 mph, then hit the brakes hard enough to lock them up
- Have your spotter confirm that both the front and rear wheels have locked up
- If the rear wheels didn’t lock up, turn the knob in two turns so the rear brakes get more force, then try again
- Keep adjusting until you have both front and rear brakes lock up on full application
- Then, turn the knob out one full turn and repeat the test once more
- If the rear brakes still lock up, turn the knob out in half-turn increments until the rear brakes don’t lock up
- Once you’re set at 30 mph, try again from 50 mph. If it’s locking up, adjust another half-turn to decrease rear pressure
This is the ideal initial setting for your brakes. From here, fine-tune the adjustment based on your performance demands.
Lever Style Valve
Sometimes, you don’t have the luxury of precisely fine-tuning your brake force over several passes in an empty lot. When you need a trial-by-fire adjustment while you’re on the go – when you’re still performing hot laps on the track – a lever-style adjustable proportioning valve might be the right solution.
There are six different positions for the lever to make adjustments:
- Like the knob style, your initial adjustment should start in the fully out position
- As with knob adjustment, inflate your tires properly, have a half-full fuel tank, and clean any unnecessary weight from the car
- Accelerate to 30 mph, then hit the brakes hard enough to lock them up
- Adjust one notch at a time until the rear brakes don’t lock up
- Test at 50 mph, adjusting so you are one notch away from locking up your rear brakes on a hard stop
However, the great thing is that the lever style can be adjusted in a second if it doesn’t feel like performing how you’d like while driving, so long as the proportioning valve is mounted where you can reach it.
When To Adjust Your Proportioning Valve
When to adjust your Wilwood proportioning valve is crucial to ensure optimal braking performance and safety. The proportioning valve's primary role is to balance the brake force distribution between the front and rear brakes, preventing rear wheel lockup and maintaining vehicle stability. Adjustments may be necessary under several conditions. Firstly, if you've upgraded to larger or more powerful brakes, the stock settings may no longer be suitable. Additionally, changes in vehicle weight distribution, such as adding or removing cargo or passengers, can affect braking dynamics, necessitating an adjustment.
Track enthusiasts and performance drivers should also consider adjusting the proportioning valve when transitioning between street and track settings. Track conditions often require a different brake balance due to higher speeds and more aggressive braking. If you notice uneven brake wear, reduced braking efficiency, or instability during hard braking, it’s a clear indication that an adjustment is needed. By fine-tuning your Wilwood proportioning valve, you can achieve a more controlled and responsive braking system, enhancing both safety and performance on the road and the track.
Need to find an adjustable proportioning valve from Wilwood? At JEGS, we’ve got them in stock. Shop some of the best prices around, and get support from our expert team, too.
