Suspension-Steering Fundamentals


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


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


Suspensions

Independent

Nonindependent


Types of Springs

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


Coil Springs


Leaf Spring Assembly


Air Springs


Torsion Bar

The bar resists twisting action and acts like a conventional spring


Control Arm Assembly

Control arm bushings act as bearings


Ball Joints

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


Shock Absorber Action


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


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


Sway Bar (Stabilizer Bar)

Sway bar links connect the barto the control arms


Front Suspension(MacPherson Strut)


Strut Compressor


Twin I-Beam Suspension


Nonindependent Rear Suspension

Solid axle housing for rear-wheel-drive


Dead Axle

Solid axle that does not drive wheels


Independent Rear Suspension

This differential is mounted to the frame


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


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


SteeringParallelogram

Steering

Basic Rack-and-Pinion Steering


27

Parallelogram Steering System

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


28

Rack-and-Pinion Steering System

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


Steering Gears

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

Worm Steering Gear(parallelogram steering)


Steering Rack(Rack and Pinion Steering)


Steering Gear box(parallelogram steering)


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


Basic Power Steering


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)


Dry Park Test

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

someone watches for part wear


Steering Inspection

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

for steering play


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


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


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

Ball socket lubrication may be necessary


Checking the Fluid

Check most systems at operating temperature, with the engine off


Tire Problem Under-inflated Tire


Tire Problem Over-inflated Tire


Tire Problem Cupping

Out of balance Lack of proper

rotation Broken belts in tire


Tire Problem Alignment Problem

Worn Parts Bent Parts


Alignment

Three Angles to check Camber Caster Toe


Camber Positive camber

Tire leans away from vehicle

Negative camber Tire leans towards

vehicle Causes tire wear Causes vehicle

pulling


47

Camber


Caster Amount of upper

and lower ball joint offset

Will cause vehicle pull

Does not cause tire wear


49

Caster


Toe measurement

difference across front and back of tires

Will cause tire wear Will result in pulling or

wandering


51

Toe Angle


Tire Future Tweel

Pneumatic tire Michelin Experimented with

in Military and Off Road applications


Tire Future

Suspension-Steering Fundamentals

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