What does the combination valve do?Combination valve repair hamilton NZ

A combination valve (also known as a proportioning valve or brake valve) is a common part found in vehicles with front brake discs and rear brake drums.

As its name suggests, the combination valve takes on a combination of different roles and is made up of several different segments:

  • The brake pressure switch
  • The metering valve
  • The proportioning valve

The brake pressure switch alerts the driver if there is a leak in your braking system. It contains a specially shaped piston that is exposed to brake pressure on either side from each brake circuit. When there is a leak or loss of brake pressure, one side will be exposed to less pressure than the other. Your car then uses this information to determine that there is a brake leak and warn the driver.

The metering valve is another important part found in the combination valve. Since disc brakes engage more quickly than drum brakes, a metering valve must be used to prevent uneven brake application. The metering valve restricts pressure to the disc brakes until a certain level of pressure is reached in the drum brakes. This allows both braking systems to be applied at the same time.

In any sort of braking system, the rear brakes do not require the same amount of pressure as the front brakes. The proportioning valve reduces the amount of pressure sent to the rear brakes. This prevents the wheels from locking up when the brakes are applied.


Have you failed your Warrant of Fitness for brake valves?

Problems with the combination valve can lead to your car becoming unsafe to drive and failing its Warrant of Fitness.

Your brake valves are assessed during your WOF to ensure correct brake operation. If the inspector deems the condition of the combination valve to be unsafe, it will need to be fixed in order for your car to be road legal.

The combination valve will fail its Warrant of Fitness if it is insecure, leaking, or corroded. Learn more about brake-related WOF requirements here.



Symptoms of a faulty combination valve:

  • Rear wheels locking up – Problems with the proportioning valve can lead to incorrect pressure being sent to the rear brakes. This means that the rear wheels will be more likely to lock up, especially on wet surfaces.
  • Brake warning lights – Problems with the combination valve system can lead to the brake or ABS warning light appearing on your dashboard.
  • Car leaning forward – When the brakes are rapidly applied, the car may lean further forward than normal.


Brake valve inspection and replacement in Hamilton

Is your car in need of a combination valve replacement due to a failed Warrant of Fitness? If so, we can help! At Grimmer Motors, our team can inspect and replace your car’s brake valves. This will ensure that your car passes its Warrant of Fitness.

For brake valve services in Hamilton. contact Grimmer Motors today!


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