A) Stop! Always Bleed Master Cylinder Before Installation.
B) No or Low Pedal Condition. Testing of Combination/Proportioning Valve
- Using the test light, attach clip to a positive and touch the point of the tester to the electrical connection of the combination valve.
- If NO light goes on, the valve system is operating correctly. No further testing is required.
- If light goes on, this indicates the pressure differential valve in the combination valve is stuck in front or rear position.
- Bleed brake system to determine which system, front or rear is not getting proper flow of fluid; one system will squirt out of the bleeder, and the other will trickle out.
- The system with the flow must be opened for the flow to alter the pressure on opposite side of pressure differential valve to center valve.
- Slowly depress pedal with steady pressure until light goes out. When light goes out close the bleeder.
- Your system is now centered. Bleed complete system.
C ) Are you doing a Disc Brake Conversion and need to add the correct valving? Here are your choices.
- Metered Valves: Used in the disc portion of a disc/drum system to hold off the application of the discs slightly allowing the drums to catch up. This provides rear stability on wet surfaces and reduces front pad wear.
- Proportioning Valves: Used in the rear to decrease the rate of pressure rise to the drums relative to pedal force as weight is shifted to the front drums during braking. This prevents the rear from locking up. Proportioning Valves are available either in a preset or adjustable configuration.
- Residual Pressure Valves: Used to hold a residual pressure in your system. You will require a 2lb to the discs if the master cylinder is lower then your calipers and a 10lb to the drums to prevent air ingestion when the brakes are released.
- Combination Valves: These valves provide metering to the front PLUS proportioning and residual to the rear. This is the recommended valve for all front disc brake conversions.
D ) To increase the life and performance of your new brakes, follow these steps.
- Make approximately 20 complete stops from 30 mph, or 20”slow down” from 50 mph to 20 mph, with light to moderate pressure.
- Allow at least 30 seconds between brake applications for the brake shoes or pads to cool down.
- You can do this as part of your normal driving time during the first 100 miles. Try to avoid hard stops during this time period also.
- Brake fluid should be changed once a year. D.O.T. 4 is recommended.
E ) Before Calling: Brake System Checklist
- Clean and flush complete hydraulic brake system before installing calipers and master cylinders.
- Use a good grade of brake fluid for best performance D.O.T. 4. Note: We do not warranty brake system parts that have silicone fluid introduced to the hydraulic system.
- Master Cylinders Test: Plug outlets with correct type and size plug (inverted flare or supplied plastic plugs). Step on pedal and hold pressure for 30 seconds. Pedal should be firm and not drop to the floor.
- Calipers: Bleeder screws should be facing to top or face upward for bleeding of air out of caliper. Sometimes it is required to remove caliper from bracket and hold it up so the bleeder screw is at 12:00 o’clock to remove all the air in the system.
- Pedal Adjustment: Always have ¼” play at top of pedal clearance. Without clearance brakes will apply or lock up wheels. Check adjustment of stop light switch.
- Valving: All types of valving should be lower than reservoir of master cylinder to function properly. All original equipment valves should be removed when combination valve is installed. Residual pressure valve should be as close to the master cylinder as possible.
- Follow the bleeding instructions that come with your master cylinder and calipers.
- Vacuum Test: Need minimum of 18” of vacuum for power booster to function correctly.
- Booster Test: With engine off, pump brake pedal to evacuate vacuum in booster. Hold foot on brake pedal, start engine, if booster is working the pedal will drop about ¼”. Vacuum may be increased by adjusting ignition timing for maximum vacuum.
- Do not fill master cylinder to top. Leave about 1” from top for heat expansion.
- Keep combo valve away from exhaust headers.
- Check brake hose length and clearance while all four wheels are on the ground.
- Booster rod adjustment between booster and master cylinder should have approximately .020 clearance.
In order for your braking system to function properly the system must be properly balanced. This is accomplished through the use of the correct valves. Below is a description of what types of valving may be used on your system. If you have any questions please feel free to contact us at 1-800-638-1703.
I’m doing a Disc Brake Conversion and need to add the correct valving. What do I use?
The valving associated with braking falls into five basic categories:
Valve Type Description
- Metering The metering or hold off valve is used in the disc portion of a disc/drum brake system to better balance the front to rear brakes. The valve does not allow the pressure to rise at the front disc brakes until the pressure at the rear drums has risen sufficiently to overcome the brake shoe springs, allowing the drums to catch up. At this point the valve opens to allow full pressure to build at the front brakes. This provides rear stability on wet surfaces and reduces front pad wear.
- Proportioning The proportioning valve modulates the pressure in the rear, to decrease the rate of pressure rise to the drums to the rear brakes. The modulation is necessary to minimize rear wheel lock up found in heavy braking and to compensate for the differences in braking conditions in front disc/rear drum systems. As pressure is applied to the system full pressure is allowed to the rear drums up to a certain point. Beyond that point the pressure to the rear is reduced preventing rear brake lock up. Relative to pedal force as weight is shifted to the front during braking. Proportioning Valves are available either in a preset or adjustable configuration.
- Residual There are two different residual valves. A ten pound residual valve will maintain a line pressure to the rear to keep the drum brake shoes out close to the drums giving a higher firmer pedal. Without a ten pound residual pressure to the rear you will experience a spongy pedal. Prevents air ingestion when the brakes are released. A two pound residual valve is required whenever the master cylinder is lower than the calipers to prevent backflow of fluid from the calipers to the master.
- Combination A combination valve incorporates metering, proportioning and 10 pound residual into one valve. These are available for disc/drum or drum/drum systems. These valves provide metering to the front PLUS proportioning and residual to the rear. This is the recommended valve for all front disc brake conversions. Available for: GM, Fords, Chryslers and Jeep.
- Adjustable Prop The adjustable proportioning valve is used when you have a special rear condition that requires higher or lower pressure than a normal condition. You should always use a metering valve to the front when using the adjustable.
- Pressure Tester
- Booster Gauge
- Vacuum Gauge
- Pedal Pressure Gauge