Servicing Your Brakes

Some auto experts feel that brakes are a part of the car that do-it-yourselfers should leave alone, since the results of a mistake could be tragic. After reading this, you yourself must decide whether you can safely perform brake servicing and repairs. Even if you decide against tackling such work, at least you should be able to detect brake problems sooner than the average motorist.

A brake is simply a heat machine that transforms energy stored up in a moving vehicle into heat. The amount of heat varies according to the square of the vehicle’s speed. Double the speed and you get four times the heat.

A single stop from 70 mph by a 4,000- pound car produces 840 BTU (British Thermal Units, a standard measure of heat quantity). You would have to burn almost 1,000 wooden kitchen matches to generate that much heat. During one such stop, the temperature of wheel brake parts can rise by 200°. Make several stops in quick succession, without allowing time for cooling, and your brakes may not be able to cope with the heat that is generated.

It seems that brake technology and materials are getting better and better as vehicles are built to last longer and longer. The basic principles are the same They all use a hydraulic fluid to transfer force to a friction material, in turn stops the vehicle. In this Web Site , I will try to explain enough of the basics for you to tackle your own vehicle.

brake lines diagram

This is a image of a basic Brake System of old.

There are many combinations of components in the newer brake systems and I will touch base on as many as I can. In the links, I broke them down to more specific components.

In the links above you can go to the troubleshooting link to help diagnose any brake related problem and in the safety link to see any requirement for the government safeties.

     Hydraulic brakes. For years, cars have used effective, dependable hydraulic brakes. These are built around a master cylinder with a pressure piston that is worked by a foot brake pedal. As you step down on the pedal, the piston in the master cylinder forces brake fluid through a system of thin steel brake lines and tough rubber hoses to each wheel. The hydraulic brake system works well because the brake fluid pressure is transmitted equally to all wheels.

In power brakes, master-cylinder hydraulic pressure is boosted by engine vacuum.

Since 1967, all U.S.-built cars have had dual hydraulic systems. In such systems, the master cylinder contains two pistons and two sets of brake lines. One set of hydraulic lines goes to the front wheels, the other set to the rear wheels. In many of the modern systems they are divided diagonally.  If one system should suffer a hydraulic failure, the other system could still stop the car—though, of course, not as quickly.

At the wheels, hydraulic wheel cylinders react to the pressure by pushing lined “shoes” outward against a rotating brake drum, or by pinching a rotating disc between lined pads or shoes. The friction of the brake linings on the drums or discs slows the wheels. Friction of the tires against the road brings the car to a stop.

A “complete” job. Brake experts do not agree on just what items should be included in a complete brake relining. One thing is certain: No shop can perform a complete, safe brake job for $19.95. A cheap brake job is like a cheap parachute.

The brakes should always be relined on both sides of the axle or, better yet, on all four wheels.

A good job, according to most experts, should also include turning all brake drums, whether or not they are badly worn. If little wear or out-of-round is found in a drum, only a light clean-up cut need be taken. Some reputable shops, however, do not normally turn drums unless they are badly worn or out-of-round.

manual brake system

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