© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Supports the weight of the vehicle Allows the wheels to move up and

down Allows rapid cornering without extreme

body roll Keeps the tires in firm contact with the

road

© Goodheart-Willcox Co., Inc.

Functions of a Suspension System

Prevents excessive body squat when accelerating or heavily loaded

Prevents excessive body dive when braking

Allows the front wheels to turn left or right for steering

Helps keep the wheels in correct alignment

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Suspensions

Independent

Nonindependent

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Types of Springs

A. Coil springB. Leaf springC. Air springD. Torsion bar

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Coil Springs

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Leaf Spring Assembly

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Air Springs

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Torsion Bar

The bar resists twisting action and acts like a conventional spring

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Control Arm Assembly

Control arm bushings act as bearings

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Ball Joints

Tapered stud provides a force fit into the steering knuckle or bearing support

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Shock Absorber Action

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Gas-Charged Shock Absorbers

Use a low-pressure gas to help keep the oil in the shock from foaming

Nitrogen gas is enclosed in a chamber separate from the main oil cylinder

Gas pressure acting on the oil prevents air bubbles from forming

© Goodheart-Willcox Co., Inc.

Checking Shock Absorber Condition

Perform a visual inspection for damage, rubber bushing wear or oil leakage

Perform a shock absorber bounce test push down on one corner of the vehicle release the body count the number of times the body

rebounds maximum two or three oscillations

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Sway Bar (Stabilizer Bar)

Sway bar links connect the barto the control arms

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Front Suspension(MacPherson Strut)

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Strut Compressor

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Twin I-Beam Suspension

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Nonindependent Rear Suspension

Solid axle housing for rear-wheel-drive

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Dead Axle

Solid axle that does not drive wheels

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Independent Rear Suspension

This differential is mounted to the frame

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Provide precise control of the wheel direction

Maintain correct steering effort Transmit road feel to the driver’s hands Absorb most of the road shock going to

the steering wheel Allow for suspension action

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Two basic kinds of steering systems are in use today: Parallelogram steering systems rack-and-pinion steering systems

Each may be operated manually or with power assist

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SteeringParallelogram

Steering

Basic Rack-and-Pinion Steering

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27

Parallelogram Steering System

Fig. 2-5Credit: ATW Assembly & Test Worldwide

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28

Rack-and-Pinion Steering System

Fig. 2-7Credit: ATW Assembly & Test Worldwide

© Goodheart-Willcox Co., Inc.

Steering Gears

Rack-and-Pinion Gear(rack and pinion steering)

Worm Steering Gear(parallelogram steering)

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Steering Rack(Rack and Pinion Steering)

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Steering Gear box(parallelogram steering)

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Power Steering Systems

Most systems use an engine-driven pump and a hydraulic system to assist steering action

An electric motor in the rack may be used to provide assist

© Goodheart-Willcox Co., Inc.

Basic Power Steering

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Steering Wheel Play Amount that you can turn the steering

wheel without front wheel movement Caused by worn ball sockets, a worn

idler arm, or too much clearance in the steering gearbox

Compare the play to service manual specifications e.g. 1 1/2” (33 mm)

© Goodheart-Willcox Co., Inc.

Dry Park Test

With the vehicle on the ground, rotate the steering wheel back and forth while

someone watches for part wear

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Steering Inspection

Raise the vehicle on a lift. Wiggle thetires back and forth while watching

for steering play

© Goodheart-Willcox Co., Inc.

Hard Steering Caused by problems with the steering

gear, power steering components, ball sockets, and the suspension system

Check the power steering pump belt for condition and tension

If the belt is slipping, hard steering could result

Check for cracks and glazing and compare tension to specs

© Goodheart-Willcox Co., Inc.

Steering System Noise Noise can be a sign of worn parts, dry

bearings or ball sockets, loose parts, slipping belts, or low power steering fluid level

Belt squeal and power steering pump noise both occur when the steering wheel is turned

Pump noise can result from low fluid level or aerated fluid

© Goodheart-Willcox Co., Inc.

Maintenance involves checking for low fluid level, incorrect belt adjustment, system leaks, and other problems

Ball socket lubrication may be necessary

© Goodheart-Willcox Co., Inc.

Checking the Fluid

Check most systems at operating temperature, with the engine off

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Tire Problem Under-inflated Tire

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Tire Problem Over-inflated Tire

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Tire Problem Cupping

Out of balance Lack of proper

rotation Broken belts in tire

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Tire Problem Alignment Problem

Worn Parts Bent Parts

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Alignment

Three Angles to check Camber Caster Toe

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Camber Positive camber

Tire leans away from vehicle

Negative camber Tire leans towards

vehicle Causes tire wear Causes vehicle

pulling

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47

Camber

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Caster Amount of upper

and lower ball joint offset

Will cause vehicle pull

Does not cause tire wear

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49

Caster

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Toe measurement

difference across front and back of tires

Will cause tire wear Will result in pulling or

wandering

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51

Toe Angle

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Tire Future Tweel

Pneumatic tire Michelin Experimented with

in Military and Off Road applications

© Goodheart-Willcox Co., Inc.

Tire Future