The proportioning valve part of the combination valve is located
in the rear brake portion of the valve
. This part of the valve probably causes the most confusion within a combination valve and is probably the most misunderstood part of a brake system.
Where is the proportioning valve normally located?
Many proportioning valves are mounted directly in
the master cylinder outlet to the rear brakes
. Height sensing proportioning valves are connected to the hydraulic lines leading to the rear drums located between the vehicle’s chassis and the rear axle.
Where is the combination valve located?
Combination Valve-Mounted: These valves are part of a larger valve with the metering valve and pressure differential switch. This type of valve is usually mounted to
the frame or inner fender below the master cylinder
.
What is the function of proportioning valve?
A proportioning valve is a valve that relies on
the statics to supply a reduced pressure to an output line
. A simple example is where spring load applies a reducing force so that the output pressure is reduced. Proportioning valves are frequently used in cars to reduce the brake fluid pressure to the rear brakes.
How do you reset a proportioning valve?
- Locate the brake proportioning valve near the rear brake line. It will have one or two buttons located on it. …
- Push the reset button located on the valve with your fingers, which will reset it so the valve is working properly again. Inspect the brake pressure.
How do you know if you have a bad proportioning valve?
Rear wheels lock up
Since the proportioning valve decreases the pressure sent to the rear brakes, the main symptom the valve is going bad is
the rear wheels locking up when the brakes are applied
. Furthermore, the wheels will lock up more easily on wet surfaces. The rear brakes may feel touchy when applied even gently.
What causes a proportioning valve to go bad?
For instance, if a truck’s cargo area is heavily loaded,
its rear end will typically drop
. This will cause the lever on the proportioning valve to work harder by supplying greater hydraulic pressure to the rear brakes compared to when the vehicle is lightly loaded.
Do you have to have a proportioning valve?
If I add disc brakes will I need a proportioning valve?
Yes
. The addition of a proportioning valve is a must. Without it your braking system will not operate properly.
Can you bypass a brake proportioning valve?
The
valve will only work as designed if
the rest of the suspension retains the original specifications – if your car is significantly lowered or the suspension stiffened up, you might as well bypass the proportioning valve.
Can a brake proportioning valve be repaired?
One such repair that can be done by a do it yourself mechanic is replacing a proportioning
valve
. This valve is important to give each brake the necessary amount of fluid to effectively operate the calipers and pads. When your is leaking, or not working properly, here are the steps necessary to replace it.
How do you use a proportioning valve tool?
Designed for use with CPP proportioning valves, these tools
lock the valve in place
and keep it from tripping when bleeding your brakes. You simply remove the warning light switch (white plug) on the valve and screw in the tool while bleeding your brakes. After the process is finished replace the warning light switch.
How do you test a brake proportioning valve?
Pressure gauges
are the best way to diagnose a failed proportioning valve. There will be a gage installed into the front and rear hydraulic circuits. Start the vehicle, and apply the brake pedal with heavy pedal pressure to duplicate a panic braking situation. The front and rear pressures should be different.
What is another name for a proportioning valve?
Conventional proportioning valves should really be referred to as “
braking force regulators”
or “brake pressure regulating valves.” While their name might imply true proportional control, in reality they provide a combination of the control found in Figures A and B.
How do I free a stuck proportioning valve?
Tap the proportioning valve with a tack hammer
several times lightly — sometimes this frees up a corroded bore and piston spool inside the valve. Wiggle the brake light warning switch wire on the top of the proportioning valve, making sure it has a tight, clean connection.
Can you bleed a proportioning valve?
The
proportioning valve doesn’t have any way to bleed air
, so you will have to bleed the front and rear brake lines in order to remove any air trapped in the valve.
