Automotive Suspension Systems Automotive Steering Suspension Alignment 4e

Automotive Suspension Systems Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The purpose of the suspension is to provide the vehicle with the following: 1. A smooth ride 2. Accurate steering 3. Responsive handling 4. Support the weight of a vehicle 5. Maintain acceptable tire wear Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

FRAME CONSTRUCTION The frame of a vehicle supports all the “running gear” of the vehicle, including the engine, transmission, rear axle assembly (if rear-wheel drive), and all suspension components. There are many terms used to label or describe the frame of a vehicle, including the following. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Ladder Frame A ladder frame is a common name for a type of perimeter frame where the transverse (lateral) connecting members are straight across. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Perimeter Frame A perimeter frame consists of welded or riveted frame members around the entire perimeter of the body. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Stub-Type Frames A stub frame is a partial frame often used on unit-body vehicles to support the power train and suspension components. It is also called a cradle on many frontwheel-drive vehicles. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Unit-Body Construction Unit-body construction (sometimes called unibody) is a design that combines the body with the structure of the frame. The body supports the engine and driveline components, as well as the suspension and steering components. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The area separating the engine compartment from the passenger compartment is called the bulkhead. The height and location of this bulkhead panel to a large degree determines the shape of the rest of the vehicle. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The track of a vehicle is the distance between the wheels, as viewed from the front or rear. A widetrack vehicle is a vehicle with a wide wheel stance; this increases the stability of the vehicle, especially when cornering. The wheelbase of a vehicle is the distance between the center of the front wheel and the center of the rear wheel, as viewed from the side. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

UNSPRUNG WEIGHT A suspension system has to be designed to allow the wheels to move up and down quickly over bumps and dips without affecting the entire weight of the car or truck. This weight is called unsprung weight. For best handling and ride, the unsprung weight should be kept as low as possible. Sprung weight is the term used to identify the weight of the car or truck, which does not move up and down and is supported or sprung by the suspension. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

TYPES OF SUSPENSIONS Early suspension systems on old horse wagons, buggies, and older vehicles used a solid axle for front and rear wheels. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Most vehicles today use a separate control arm-type of suspension for each front wheel which allows for movement of one front wheel without affecting the other front wheel. This type of suspension is called independent front suspension. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Springs A suspension spring serves two purposes. First, it acts as a buffer between the suspension and frame to absorb vertical wheel and suspension movement without passing it on to the frame. Second, each spring transfers part of the vehicle weight to the suspension component it rests on, which transfers it to the wheels. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Spring Materials. Most springs are made of a tempered steel alloy known as spring steel, usually chrome silicon or chrome-vanadium alloy. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

COIL SPRINGS Coil springs are made of special round spring steel wrapped in a helix shape. The strength and handling characteristics of a coil spring depend on the following. 1. Coil diameter 2. Number of coils 3. Height of spring 4. Diameter of the steel coil that forms the spring Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The larger the diameter of the steel, the “stiffer” the spring. The shorter the height of the spring, the stiffer the spring. The fewer the coils, the stiffer the spring. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Springs are designed to provide desired ride and handling and come in a variety of spring ends. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Spring Rate Spring rate, also called deflection rate, is a value that reflects how much weight it takes to compress a spring a certain amount. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

A constant-rate spring continues to compress at the same rate throughout its complete range of deflection. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

A variable-rate spring may compress one inch under a 100 -pound load, but only compress an additional half an inch under a 200 -pound load. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Before a spring is installed on a vehicle or any load is placed on it, it is at its uncompressed length, or free length. Once installed, the weight of the corner of the vehicle resting on the spring is called its static load. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Coil Spring Mounting Coil springs are usually installed in a spring pocket or spring seat. Hard rubber or plastic cushions or insulators are usually mounted between the coil spring and the spring seat. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Spring Coatings All springs are painted or coated with epoxy to help prevent breakage. A scratch, nick or pit caused by corrosion cause a stress riser that can lead to spring failure. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Instead of cutting springs to lower a vehicle, there are several methods available that are preferred if the vehicle must be lowered: 1. replacement springs 2. replacement spindles Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

LEAF SPRINGS Leaf springs are constructed of one or more strips of long, narrow spring steel. These metal strips, called leaves, are assembled with plastic or synthetic rubber insulators between the leaves, allowing freedom of movement during spring operation. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The ends of the spring are rolled or looped to form eyes. Rubber bushings are installed in the eyes of the spring and act as noise and vibration insulators. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The leaves are held together by a center bolt, also called a centering pin. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

One end of a leaf spring is mounted to a hanger with a bolt and rubber bushings directly attached to the frame. The other end of the leaf spring is attached to the frame with movable mounting hangers called shackles. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Rebound or spring alignment clips help prevent the leaves from separating whenever the leaf spring is rebounding from hitting a bump or rise in the roadway. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Single leaf steel springs, called mono leaf, are used on some vehicles. A single or mono leaf spring is usually tapered to produce a variable spring rate. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

To provide additional load-carrying capacity, especially on trucks and vans, auxiliary or helper leaves are commonly used. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Composite Leaf Springs Fiberglass-reinforced epoxy plastic leaf springs have been used on production vehicles. Using 70% fiberglass with 30% epoxy composite. Leaf spring rate increases when the thickness increases, and decreases as the length increases. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

TORSION BARS A torsion bar is a spring which is a long, round, hardened steel bar similar to a coil spring except for a straight bar. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

One end is attached to the lower control arm of a front suspension and the other end to the frame. When the wheels hit a bump, the bar twists and then untwists. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

SUSPENSION PRINCIPLES 1. Transverse (or side-to-side) wheel support. Transverse links are also called lateral links. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

2. Longitudinal (front-to-back) wheel support. Some suspension designs use an additional member to control forward-back movement. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

STEERING KNUCKLES A steering knuckle is hard to classify either as part of the suspension or as part of the wheel. A knuckle serves two purposes: To join the suspension to the wheel To provide pivot points between the suspension and wheel Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The only knuckle that uses a kingpin is a steering knuckle on an I-beam or twin Ibeam front suspension. The steering axis is the vertical center of the kingpin. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

CONTROL ARMS A control arm is a suspension link that connects a knuckle or wheel flange to the frame. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

BALL JOINTS Ball joints are actually ball-and-socket joints, similar to the joints in a person's shoulder. Ball joints allow the front wheels to move up and down, as well as side to side (for steering). Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

If the coil spring is attached to the top of the upper control arm, then the upper ball joint is carrying the weight of the vehicle and is called the load-carrying ball joint. The lower ball joint is called the nonload carrying or follower ball joint. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

If the coil spring is attached to the lower control arm, then the lower ball joint is the load-carrying ball joint and the upper joint is the follower ball joint. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Ball Joint Design There are two basic designs of ball joints: compression loaded and tension loaded. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

A ball joint that does not support the weight of the vehicle and acts as a suspension pivot is often called a follower ball joint or a friction ball joint. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

STRUT RODS Some vehicles are equipped with round steel rods which are attached between the lower control arm at one end and the frame of the vehicle with rubber bushings, called strut rod bushings, at the other end. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Strut rods are also called tension or compression rods or simply TC rods. Some vehicle manufacturers call the strut rod a drag rod because it was attached in front of the wheels, and therefore acted on the lower control arm as if to drag the wheels behind their attachment points. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

If a strut rod has a nut on both sides of the bushings, then the strut rod is used to adjust caster. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

STABILIZER BARS Most cars and trucks are equipped with a stabilizer bar on the front suspension, which is a round, hardened steel bar (usually SAE 4560 or 4340 steel) attached to both lower control arms with bolts and rubber bushing washers called stabilizer bar bushings. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

A stabilizer bar is also called an anti-sway bar (sway bar) or anti-roll bar (roll bar). A stabilizer bar operates by twisting the bar if one side of the vehicle moves up or down in relation to the other side, such as during cornering, hitting bumps, or driving over uneven road surfaces. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Stabilizer links connect the ends of the stabilizer bar to the lower control arm. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

SHOCK ABSORBERS Shock absorbers are used on all conventional suspension systems to dampen and control the motion of the vehicle's springs. Without shock absorbers (dampers), the vehicle would continue to bounce after hitting bumps. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

The major purpose of any shock or strut is to control ride and handling. Standard shock absorbers do not support the weight of a vehicle. The springs support the weight of the vehicle; the shock absorbers control the actions and reactions of the springs. Shock absorbers are also called dampers. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

As a wheel rolls over a bump, the wheel moves toward the body and compresses the spring(s) of the vehicle. As the spring compresses, it stores energy. The spring then releases this stored energy, causing the body of the vehicle to rise (rebound). Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Shock Absorber Operation The hydraulic shock absorber operates on the principle of fluid being forced through a small opening (orifice). Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Gas-Charged Shocks Most shock absorbers on new vehicles are gas charged. Pressurizing the oil inside the shock absorber helps smooth the ride over rough roads. This pressure helps prevent air pockets from forming in the shock absorber oil as it passes through the small passages in the shock. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Some gas-charged shock absorbers use a single tube that contains two pistons that separate the high-pressure gas from the working fluid. Single tube shocks are also called monotube or De. Carbon after the French inventor of the principle and manufacturer of suspension components. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Remote Reservoir Shocks Remote reservoir shock absorbers are units designed for heavy-duty use that use a separate container for the working fluid. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Air Shocks/Struts Air-inflatable shock absorbers or struts are used in the rear of vehicles to provide proper vehicle ride height while carrying heavy loads. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Air-inflatable shocks are standard shock absorbers with an air chamber with a rubber bag built into the dust cover (top) of the shock. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Air Springs Some electronically controlled suspension systems use air springs. A basic air spring consists of a rubber air chamber, generally closed at the bottom by a piston fitted into a control arm, or by a strut shock absorber. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Some air springs are in effect auxiliary springs inside a coil-spring strut. In these designs, the coil spring supports the weight of the vehicle, while the air spring raises or lowers the body to adjust ride height according to load. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Coil-Over Shocks A coil-over shock absorber uses the force of an external coil spring to boost the performance of the basic shock absorber. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

STRUTS A strut is a sturdy shock absorber that is also a structural component of the suspension. A strut is a suspension link as well as a shock absorber. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Mac. Pherson Struts The Mac. Pherson strut, which is named after Earle S. Mac. Pherson, who developed the suspension design in the late 1940 s and patented it in 1953, is the most commonly used type. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Modified Struts Unlike a Mac. Pherson unit, a modified strut does not include a spring as part of the assembly and is used in the front on some vehicles and on the rear of others. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

BUMP STOPS All suspension systems have a limit of travel. If the vehicle hits a large bump in the road, the wheels are forced upward toward the vehicle with tremendous force. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

Instead of allowing the metal components of the suspension to hit the frame or body of the vehicle, a rubber or foam bumper is used to absorb and isolate the suspension from the frame or body. These bumpers are called bump stops, suspension bumpers, strike-out bumpers, or jounce bumpers. Jounce means jolt. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

SUMMARY 1. The lighter the wheel/tire combination, the lower the unsprung weight and the better the ride and handling of the vehicle. 2. All springs – including the coil, leaf, and torsion bar types – share Hooke's Law, which states that the force exerted by the spring is directly proportional to the amount the spring is deflected. 3. All springs are similar to torsion bars. As the torsion bar becomes longer or smaller in diameter, it becomes easier to twist. If a coil spring is cut, the remaining spring is shorter, yet stiffer. 4. Ball joints attach to control arms and allow the front wheels to move up and down, as well as turn. 5. Suspension designs include a straight or solid-axle, two-control-arm-type called an SLA or a Mac. Pherson strut. 6. All shock absorbers dampen the motion of the suspension to control ride and handling. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458

REVIEW QUESTIONS 1. List the types of suspensions and name their component parts. 3. Describe the purpose and function of a stabilizer bar. 3. Explain the difference between a load-carrying and a friction ball joint. Automotive Steering, Suspension, & Alignment, 4/e By James D Halderman © 2008 Pearson Education, Inc. Pearson Prentice Hall Upper Saddle River, NJ 07458