What does the proportioning valve do?

The proportional valve (or combination valve) is an important part of some ABS/braking systems. It helps to distribute braking force evenly between the front and rear brakes. It regulates the amount of pressure that is sent to the rear brakes to prevent the rear wheels from locking up during hard braking, which can cause the car to skid or lose control.

The proportioning valve is an important safety feature that helps to maintain stability and control during braking. It works by reducing the pressure to the rear brakes when the brakes are applied hard, and increasing the pressure to the rear brakes when the brakes are applied lightly. This helps to ensure that the front and rear brakes work together to bring the car to a stop as quickly and safely as possible.


Causes of proportioning valve failure:

The proportioning valve can fail due to several reasons, including:

  • Worn or damaged components: Over time, the components inside the proportioning valve can wear out, become damaged, or become clogged with debris, causing the valve to fail.
  • Leaks: If the proportioning valve or its components develop leaks, this can cause a reduction in pressure to the rear brakes, making it difficult to stop the car.
  • Rust and corrosion: If the proportioning valve becomes corroded, this can cause it to seize or become clogged, preventing it from functioning properly.
  • Electrical failure: If the electrical connections or wiring to the proportioning valve fail, this can prevent it from functioning properly.


Symptoms of a malfunctioning proportioning valve:

  • Rear-wheel locking – The most common sign of a failing proportioning valve is the rear wheels locking. When braking hard, you may notice that you have little or no control over the back of your vehicle.
  • Nose-diving – When the brakes are applied hard, the vehicle may lean forward. This can be due to the proportioning valve not working correctly.
  • ABS light on – If there is a problem with your brake pressure, the ABS light will turn on. A fault code will be stored on your car’s computer which can be read with a diagnostic tool.


Is it safe to drive with a broken proportioning valve?

We recommend against driving with a damage/broken proportioning valve.

A failing proportioning valve can result in uneven braking performance, making it difficult to stop the vehicle in an emergency situation. The rear wheels may lock up during hard braking, causing the car to skid or lose control, which can be dangerous and increase the risk of an accident.

If you think that your proportioning valve is broken or failing, it is recommended to have it inspected and replaced by a professional as soon as possible. Driving with a failing proportioning valve can compromise the safety of you and your passengers, as well as others on the road.


Proportioning valve replacement in Hamilton

Do you think your proportioning valve is in need of replacement? If so, we are happy to help!

At Grimmer Motors, our reputable,  skilled, and qualified mechanics are able to perform a proportioning valve replacement on your vehicle. This will allow for smoother, safer braking. We can also perform diagnostics on your car’s ABS system with the latest scan tools. This lets us quickly identify issues, saving you time and money.

For reliable, experienced mechanics in Hamilton, contact Grimmer Motors today!

Please Note – we don’t generally stock or supply just “parts only” for this service. We are a general automotive repair workshop. If you are able to bring your vehicle to us, we can diagnose the problem, find and fit the necessary parts, or organise the appropriate service for you.


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