Repair And Fix it

You can adjust the rear drum brakes on your Saturn right from your home garage, saving yourself time and money. You should adjust the rear brakes periodically to keep them in the best working condition. As you use your brakes, they wear down a bit causing a space between the shoes and the drum. To close up this space, you need to do an adjustment with a few basic tools you can purchase from your local auto parts retailer.

Instructions

1

Disengage the parking brake. Place a wheel chock behind each of the Saturns front wheels to keep the vehicle from accidentally moving while you work.

2

Lift up the rear of the car with a floor jack, high enough to slide the jack stands underneath the car next to each control arm by the wheels. Slide the jack stands into place and lower the car onto them.

3

Put on a respirator mask, which you can purchase from any hardware store, to protect yourself from brake pad dust. Remove the lug nuts with a lug wrench. Take off the wheel and set it aside with the lug nuts.

4

Twist off the drums clockwise. If they are stuck, strike them with a hammer gently and twist again.

5

Locate the star-shaped self-adjuster under the wheel cylinder. Spread the shoes open a bit by turning the self-adjuster. Slip the drums back onto the shoes. They should slide on easily if you did the adjustment correctly.

6

Put the wheels back on the Saturn and tighten the lug nuts. Lift up the car with the jack and slide the jack stands out. Lower the car to the ground. Lift up on the parking brake, which should only move up six notches maximum.

7

Tighten the lug nuts all the way with the lug wrench and remove the wheel chocks.

An automobile is a collection of systems working together to accomplish a few simple tasks: to stop, go, turn and not fall apart in the process. Each system relies on multiple scientific principles to control and convert energy from one source and apply it to another. A power brake system uses energy from the drivers leg and from the engine to force hydraulic fluid through brake lines. That energy expresses itself on the pistons in the brake calipers, which force the brake pads against rotors. This process completes a complex dance of physics and sheer necessity, expressed in a very ordinary way.

Conservation of Energy

Otherwise known as the "First Law of Thermodynamics," this principle states that energy can never appear or disappear, it can only change forms. When a car accelerates, its using the chemical energy stored in gasoline and converting it into momentum, or kinetic energy. To stop the car, you need to convert that kinetic energy into another form. A braking system uses brake pads to squeeze down on a smooth surface known as the rotors or drums to create frictional heat, thus converting the cars kinetic energy into thermal energy. That heat, at some point transfers to either the air around the rotor or into the components and fluid adjacent to the pads and rotor.

Incompressible Fluids

The difference between a gas and a liquid is that liquids are a solid mass of molecules or atoms, theres no empty space between them. This means that no matter how hard you squeeze a liquid, it never gets any smaller or compresses. Power brake systems use this principle known as hydraulics to transfer energy imparted onto the brake master cylinder or main hydraulic ram to another set of cylinders in the brake calipers. When the driver puts his foot down on the pedal, the energy he puts into it travels through the master cylinder, through the lines, into the brake calipers and ultimately expresses on the brake pads and rotors.

Differential Pressure as Energy

Most power brake systems use vacuum suction created by the engine to pull on a diaphragm, which is connected to the back of the master cylinder. When the driver pushes the brake pedal, a valve opens in one chamber of the diaphragm. Engine vacuum pulls on the diaphragm and subsequently the master cylinder piston, imparting energy of its own to the braking system, thus reducing the amount of energy the driver must expend to push fluid through the lines.

Vacuum as an entity doesnt actually exist; "vacuum" is a term to describe the absence of air and air pressure. When the vacuum valve opens in the diaphragm chamber, atmospheric air pressure, which is about 14 psi at sea level, pushes on the other side of the diaphragm membrane. The engine itself actually provides the energy, since it took energy from the gasoline to create the vacuum in the first place. Atmospheric pressure is just a static factor. Think of this like doing a push-up. You, as the engine, actually provide the energy that causes your body to move; the floor or atmospheric pressure, is simply the surface upon which you express that energy.