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Brake Proportioning Valve Replacement Cost

Know what price you should pay to get your vehicle fixed.

The average cost for a Brake Proportioning Valve Replacement is between $179 and $458. Labor costs are estimated between $88 and $167 while parts are priced between $91 and $291. Estimate does not include taxes and fees.
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What is a Brake Proportioning Valve?

As brake systems developed, but before anti lock brake actuators were used, the brake proportioning valve was used to prevent excessive brake pressure to the rear brakes, especially when front disc brakes were used. These valves slow the reaction of the front disc brakes until the rear drum brakes are applied with great enough force. This prevents the rear of the vehicle rear of the vehicle from sliding during normal or hard braking.

How does a Brake Proportioning Valve work?

Brake proportioning valves work by receiving hydraulic pressure from the brake master cylinder via metal brake lines, and the plungers, valves and springs inside the proportioning valve are designed to allow only braking pressure to the rear of the vehicle until the spring and plunger are overcome by hydraulic pressure from the master cylinder. This design allows a preload on the rear brakes before the front brakes are fully applied. There are two major types of proportioning valves that have been used over the last several decades, and though they may use different methods of actuation, they both complete the same job mechanically and hydraulically, without computer control.

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What are the symptoms of a bad Brake Proportioning Valve?

When the brake proportioning valve fails, the result will be disproportional braking between the front and rear of the vehicle. This will result in the vehicle either diving in the front during normal or heavy braking, or the rear brakes will lock during normal or severe braking while the front brakes decrease in braking force. The rear of the vehicle will be more prone to sliding under both conditions. Another sign of failure is the brake warning lamp in the instrument cluster may illuminate. This indicates hydraulic failure of the proportioning valve, but may also be indicative of a brake fluid line leak in the rear of the vehicle.

Can I drive with a bad Brake Proportioning Valve?

Any problem with the brake system from squeaky brakes to total failure should be inspected immediately. In the case of the proportioning valve, the vehicle will be very prone to sliding in an emergency, and likely to slide under normal braking. This can pose a serious hazard to passengers and other vehicles on the road. If the brake warning light illuminates, the vehicle should not be driven, as a brake fluid leak will eventually cause total brake system failure.

How often do Brake Proportioning Valves need replacement?

Brake proportioning valves have an excellent track record for dependability, but the old style of brake systems used on these vehicles do not have such a great overall dependability rating. Older brake systems using drm brakes and poorly sealed master cylinder reservoirs are prone to leaks, and these leaks breed contamination. Contamination is the leading cause of brake component failure, and the brake proportioning valve is dually sensitive due to tight clearances and small valves. Still, at least 100,000 miles could be expected reasonably from a proportioning valve, and ever more if proper brake fluid flushes are conducted on time.

How are Brake Proportioning Valve issues diagnosed?

A complete brake system inspection is necessary to identify the cause of brake light illumination for these older systems. That is because the most likely cause of the brake warning light is a leak in the brake system allowing a plunger to activate the brake light warning switch. If no leak is visible, bleeding the brakes may be a diagnostic approach used to identify air trapped in the brake proportioning valve due to a period of low fluid in the brake master cylinder reservoir. For all other cases, the technician will notice the performance of the front brakes verses the rear brakes, and may perform a cleaning and adjustment of the rear brake drums before deciding the proportioning valve is faulty. Since a clog may be the cause of the proportioning valve failure, the brakes will be bled to search for restrictions in any of the four brakes, and once any clogs are removed, the system will be closed and tested.

How are Brake Proportioning Valves replaced?

Replacing a proportioning valve requires complete removal of fluid from the brake system, and this will typically be done by suction from all four service brake bleeder valves. This will not only contain leaks, but it will confirm that all contaminated fluid is out of the system. Once the brake system is cleared of fluid, the proportioning valve will be disconnected from the brake lines before removing mounting hardware and fasteners. This will prevent damage and twisting of the brake lines. The new valve is installed in reverse order, and the brake system will be flushed with new fluid, the master cylinder bled, then the rest of the system will be bled of air before test driving the vehicle.

RepairPal Recommendations for Brake Proportioning Valve issues

We recommend using the factory approved brake fluid for the vehicle being repaired, and not mixing any types of brake fluid. Also, the brake system should be flushed and inspected for obvious signs of deterioration, and repaired if necessary to prevent further failure. If the Entire brake hydraulic system is replaced, a new type of brake fluid may be used, but it must be at least the minimum standard of when the vehicle was manufactured.

What to look out for when dealing with Brake Proportioning Valve issues

Mixing brake fluid can lead to brake system failure due to congealing of the fluid within the brake lines. The different types of brake fluid, i.e. DOT3, DOT4, or DOT5 are meant for higher and higher braking demand, and will not always result in better braking performance. In fact, except for the most strenuous braking conditions, upgrading brake fluid will likely have no benefit.

Can I replace the Brake Proportioning Valve myself?

Proportioning valve replacement is an easy task as long as a good knowledge of hydraulic system maintenance and operation is understood. The informed and experienced DIYer can tackle the diagnosis and repair of the brake proportioning valve in a few hours, but proper bleeding and diagnostic procedures must be understood and followed.

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