1 Fundamentals Suspension & 4-Wheel Alignment. 2 Why Alignment? All Wheels must steer correctly in all directions

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FundamentalsSuspension & 4-Wheel

Alignment

2

Why Alignment? All Wheels must steer correctly in all

directions

3

How does a car “Get out of alignment”?

Cars do not get out of alignment!! Something Happens!!Worn PartsBent or Broken PartsSomebody Set it WrongOthers???

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Suspension Types

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Independent Suspensions

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Suspension Types

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9


10


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12


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Springs

Coil Spring

Torsion Bars

Air Spring

Transverse Leaf(Composite Material)

Multi-Leaf

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Torsion Bars

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Torsion Bars

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Coil Springs

Spring Spring RateRate

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Coil Springs


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Coil Springs


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Coil Springs


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Coil Springs


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Leaf SpringsTransverse

Leaf(Composite Material)

Multi-Leaf

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Air Springs

Note: Must turn system off on Ford ProductsNote: Must turn system off on Ford Products

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Shock Absorber Principle

Without Dampening With Dampening Piston Rod Seal

Reserve Fluid

Piston / Valving

Fluid Under Pressure

Base Valve

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25


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27


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Control Arm Bushings

Metal Bushing Rubber Bushing

Inner Pivot Points

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Checking Ball Joints

With Spring on the Lower Control Arm

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Checking Ball Joints

With Spring on the Upper Control Arm

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Wear Indicator Ball Joints

Protruding = GOOD

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Strut Rod

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Stabilizer Bar / Sway Bar

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Steering Linkages

Parallellogram

Cross Steer

Haltenberger

Center Steer

Rack and Pinion

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Steering Gear Principle

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Pitman Arm

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Idler Arm

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Idler Arm Check

1/4”

25 lbs

25 lbs

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Center Link

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Tie Rods / Ends / Sleeves

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Tie Rod Tightening

Incorrect Clamp Alignment

Correct Clamp Alignment

Tie Rod Stud Alignment

Incorrect Correct

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Steering Systems Compared

Parallelogram

Rack & Pinion

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Rack & Pinion Principle

Rack

Pinion

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Power Rack & Pinion System

Power Steering

Pump

Fluid pressure routed

by steering

Return Fluid displaced

by the piston

Spool Valve

Return Fluid

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Pre-Alignment Inspection

Dry Park Check• Steering Linkage Parts

• Sway Bar System

• Ride Height

• Control Arm Bushings

• Wear Indicator Ball Joints

• Tire Size and Pressure

Raised Position• Load Carrying Ball Joints

• Wheel Bearings

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Tire Wear Pattern Inspection

Even Tread Wear

Center Tread Wear

Both Shoulder

Tread Wear

Feathered or Sawtooth

Tread Wear

Single Shoulder

Tread Wear

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Ride Height

Check Spec Manual for Specs and Measurement Point

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Camber Definition

Lean IN = Negative Lean OUT = Positive

•Tire C/L•Vertical

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Camber Definition

Outside Tire WearInside Tire Wear

Negative PositiveZero

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Camber Pull

Pulls to the side having the most Camber

28” 27”

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Typical Single Point Adjustments

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Typical Dual Point Camber Adjustments

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Asymmetric Control Arms

Caster AdjustmentCaster Adjustment

Camber AdjustmentCamber Adjustment

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Caster Definition

Rearward Tilt = Positive Forward Tilt = Negative

•Steering Pivot Centerline

•Vertical

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Caster Definition

Excessive Positive = Hard SteeringExcessive Negative = InstabilityAdjust under normal load or ElevatedPulls to side having the least Caster

Zero Caster

Negative Caster

Positive Caster

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Caster Adjustment Methods

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Shim Calculations

Shim Camber CasterSize Change Change1/8" 1/2 deg 1 deg1/16" 1/4 deg 1/2 deg1/32" 1/8 deg 1/4 deg1/64" 1/16 deg

Reading

Specifications

Amount of Change

Shims Required

CAMBER CASTER

Combined Shim Amounts

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Shim Calculations

Reading

Specifications

Amount of Change

Shims Required

CAMBER CASTER


.5

0

-.5

1/8”

out 1/8”

out 1/8”

3.5

3.5

0

0

0

0

out 1/8”

out 1/8”


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Shim Calculations

Reading

Specifications

Amount of Change

Shims Required

CAMBER CASTER


.5

.5

0

0

0

0

3.5

2.5

-1

1/8”

in 1/16”

out 1/16”

in 1/16”

out 1/16”


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Shim Calculations

Reading

Specifications

Amount of Change

Shims Required

CAMBER CASTER


.5

0

-.5

1/8”

in 1/8”

in 1/8”

3.5

2.5

-1

1/8”

in 1/16”

out 1/16”

in 3/16”

in 1/16”


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Using “A-Arm Adjust” Software

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Total Toe

The difference in the distance measured between the leading edges and trailing edges of the wheel and tire assembly, at spindle height.

Total Toe

Total Toe

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Toe Conditions

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Adjusting Toe

1. Level and Lock Steering Wheel

2. Loosen Tie Rod Adjust Sleeves

3. Adjust One Side to Preferred

3. Adjust the Other Side to Preferred

4. Unlock Steering Wheel, Re-center

5. Readjust Toe if Necessary

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Thrust Angle

GeometricCenterline

Thrustline

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Thrust Angle

The Thrust Angle dictates the vehicle's roll direction. The driver steers, in the direction of the Thrust Angle, to compensate for the out of thrust condition. This results in the steering wheel being cocked, in the direction of the Thrust Angle, when the vehicle is in motion.

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Steering Axis Inclination

The tilt inward of a line drawn between the wheel's pivot points, as viewed from the front of the car, compared to true vertical

SAI

Included Angle

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Scrub Radius

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Wide Rim Effect

Scrub Radius changes with rim width & offset

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Steering Axis Inclination

SpindleArc

SAI

Included Angle

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Spindle Diagnostics

Camber is OK SAI is OK Incl’d Angle is OK Spindle is OK

Included Angle

SAI

Camber

Vertical

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Spindle Diagnostics

Camber is Less SAI is High Incl’d Angle is OK Adjust Camber Spindle is OK

Included Angle

SAI

Camber

Vertical

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Spindle Diagnostics

Camber is OK SAI is High Incl’d Angle is High Spindle is Damaged

Included Angle

SAI

Camber

Vertical

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Spindle Diagnostics

Camber is OK SAI is Less Incl’d Angle is LessSpindle is Damaged

Included Angle

SAI

Camber

Vertical

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FWD Engine Cradle

Lower Inner Pivots

Upper Inner Pivots

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FWD Engine Cradle

Camber is High SAI is Low Incl’d Angle is OK

Camber is Low SAI is High Incl’d Angle is OK

Cradle Shifted

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Using Cradle Adjust Software

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Toe Out On Turns

When a car steers into a turn, the two steerable tires must

turn on two different size circles. The entire car turns

about a common center. This means that the two steerable

tires must turn on two different size angles, with the tire on the

inside of the turn having the greater angle

All Wheels Turn on a Common

Center

20o turn

18o turn

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Toe Out On Turns

Check Specifications for Inside and Outside Turn Angle

18o turn 20o turn

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Setback

Setback occurs when one wheel on an axle is set slightly behind the other wheel

on the axle.

Documents

1 Fundamentals Suspension & 4-Wheel Alignment. 2 Why Alignment? All Wheels must steer correctly in all directions