67 to 70 Suspension-Steering FundamentalsI

8/9/2019 67 to 70 Suspension-Steering FundamentalsI

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Goodheart-Willcox Co., Inc.


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Supports the weight of the vehicle

Allows the wheels to move up anddown

Allows rapid cornering without extreme

body roll Keeps the tires in firm contact with the

road


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Functions of a

Suspension System Prevents excessive body squat when

accelerating or heavily loaded

Prevents excessive body dive whenbraking

Allows the front wheels to turn left orright for steering

Helps keep the wheels in correctalignment


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Suspensions

Independent

Nonindependent


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Types of Springs

A. Coil spring

B. Leaf spring

C. Air spring

D. 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


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Checking Shock

AbsorberCondition 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 bar

to 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


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Provide precise control of the wheel

direction

Maintain correct steering effort

Transmit road feel to the drivers 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 SteeringSystem

Fig. 2-5

Credit: ATW Assembly & Test Worldwide


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28

Rack-and-Pinion SteeringSystem

Fig. 2-7

Credit: ATW Assembly & Test Worldwide


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Steering

Gears

Rack-and-PinionGear

(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 motorin the rack may be

used to provide assist


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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 wornidler arm, or too much clearance in the

steering gearbox

Compare the play to service manualspecifications

e.g. 1 1/2 (33 mm)


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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 the

tires back and forth while watching

for steering play


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Hard Steering Caused by problems with the steering

gear, power steering components, ballsockets, and the suspension system

Check the power steering pump belt forcondition and tension

If the belt is slipping, hard steering

could result Check for cracks and glazing and

compare tension to specs


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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 steeringwheel is turned

Pump noise can result from low fluidlevel or aerated fluid


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Maintenance involves checking for lowfluid level, incorrect belt adjustment,

system leaks, and other problems

Ball socket lubrication may benecessary


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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 properrotation

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 causevehicle 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


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Tire Future

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67 to 70 Suspension-Steering FundamentalsI

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