Master Cylinder/Power Booster Conversion

Time: 2 hours (approximately) Tools: standard socket set, standard wrenches, brake bleeder (optional) Cost: 250 and up Tinware: master cylinderpower booster Tip: Always bleed the brakes repeatedly anytime changes are made in the brake system. Performance gains: A new, dual circuit master cylinder and booster will enhance the ease and safe operation of your brake system. Most vehicles on the road today, both old and new, use hydraulic systems to actuate the brakes. Hydraulic systems allow to be delivered through small diameter hoses and lines from the to the braking surfaces at each wheel without taking up a large amount of room. They also decrease the amount of foot required by making the surface area of the master cylinder smaller than that of the wheel cylinder or caliper The master cylinder consists of a fluid reservoir mated to a cylinder and assembly. Late models (typically came equipped with a dual reservoir master cylinder. The dual reservoir was designed to separate the front and rear braking systems hydraulically in case of a leak. These dual circuit master cylinders utilize two a and a secondary, to keep the braking system safely in order. The is actuated mechanically by the linkage of the brake The secondary located directly behind the is set in motion by trapped fluid between the two If a leak occurs forward of the secondary it will move forward to the front of the master cylinder, and the trapped fluid between the two will operate the rear brakes. If the rear brakes develop a leak, the advances until it reaches the secondary forcing it to apply to the front brakes. In the unfortunate circumstance of a system failure or leak, most dual circuit systems use a switch to warn the driver that only half of the braking system is working This switch is either mounted on the firewall or on the frame of the vehicle below the master cylinder. A hydraulic receives equal on both sides from the two circuits. If the remain even and stable, the is stationary. If there is a leak in either circuit and the is to one side, the switch is closed and the warning light is activated. On disc brake equipped cars, this switch mechanism also contains a metering valve and often, a valve. Metering valves restrict to the front brakes until the rear shoes have been engaged to the drums. Proportioning valves, on the other hand, control fluid to the rear brakes to avoid rear wheel lock-up during extreme braking. Checking for leaks in the system can be made by slowly applying to the brake If the sinks to the floor, a leak is guaranteed. If no external leaks are detected along the brake lines or at the wheel cylinders, the is inside the master cylinder. When the hydraulic system is at rest, it is full of fluid. Applying to the brake forces the trapped fluid in front of the master cylinder through the lines and to the wheels. On drum brake systems, the wheel cylinder are outward by the fluid toward the brakes shoes, and retrieved by return springs. The are directed inward toward the rotors on disc brake applications, and returned by spring seals. When the is released, a spring located inside the master cylinder returns the to their normal The will retract faster than the return flow of fluid, therefore the fluid from the reservoir is used to a vacuum in the system. Many aftermarket companies sell master cylinders and boosters complete as one assembly. The addition of a booster in conjunction with a dual circuit master cylinder translates to lighter foot and shorter distances of travel in the brake In other words, boosters make life easy. They are actuated by vacuum from the intake manifold through a small diaphragm located at the front of the master cylinder. A check valve is at the of the diaphragm to ensure that brake-assisted vacuum will not be lost during of low manifold vacuum. When the brake is depressed, the vacuum source is shut off and atmospheric is allowed to enter one side of the diaphragm. This causes the of the master cylinder to move and apply to the brakes. By releasing the vacuum is applied to both sides of the diaphragm and springs return the master cylinder to their original After the fluid has been drained, remove the old master cylinder from the firewall. The clevis and lock-pin at the rear of the booster attach directly to the linkage of the brake To remove the old master cylinder from the firewall, first suck the brake fluid out of the reservoir with a siphon. Loosen the fittings and disconnect the brake lines from the side of the master cylinder. Its important to cover or cap the lines to avoid contaminants from entering the system. Remove the nuts and washers securing the master cylinder to the firewall. Remove the clevis lock-pin and disengage the master cylinder at the brake To install the new master cylinder with the booster, attach the to the and line up the boosters mounting holes on the firewall. Loosely tighten the booster to the studs and reattach the hard lines to the master cylinder. Once everything is in tighten as necessary. Refill the reservoir with clean brake fluid and check for any leaks. The new assembly may require alteration or replacement of some hard lines. If you are unable to make the old lines adapt to the of the new master cylinder, you may need to hand-bend or fabricate new lines. Be sure to thoroughly bleed the entire system before attempting to move the car.