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171

CHAPTER OVERVIEW

This chapter explains the care and service of tires and wheels. Factors that affect the per-formance and longevity of the tires are also explained.

CHAPTER OBJECTIVES

Describe the basic wheel and hub design.Recognize the basic parts of a tubeless tire.Explain the difference between the three types of tire construction in use today.Explain the tire ratings and designations in use today.Describe why certain factors affect tire performance, including inflation pressure,tire rotation, and tread wear.Remove and install a wheel and tire assembly.Dismount and remount a tire.Repair a damaged tire.Describe the differences between static balance and dynamic balance.Balance wheels both on and off a vehicle.Describe the three popular types of wheel hub bearings.

INSTRUCTIONAL OUTLINE WITH TEACHING HINTS

I. WheelsII. Tires

A. Tube and Tubeless TiresB. Types of Tire Construction

1. Bias Ply2. Belted Bias Ply3. Radial Ply

C. Specialty TiresD. Tread DesignsE. Spare TiresF. High-Performance (Speed-Rated) Tires

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G. Tire Ratings and DesignationsH. Tire PlacardI. Tire Care

1. Inflation Pressure2. Tire Rotation

3. Tread WearJ. Tire Pressure Monitor (TPM)K. Run-Flat Tires

Hint: Describe how proper tire care increases the longevity of the tires.Explain why rotation is important.

IV. Tire RepairA. Repair Methods

1. Plug Repair2. Cold Patch Repair3. Hot Patch Repair

B. Installation of Tire/Wheel Assembly on the VehicleV. Tire/Wheel Runout

VI. Tire/Wheel Assembly ServiceA. Tire/Wheel Balance

1. Static Balance2. Dynamic Balance

VII. Wheel BearingsA. Front Wheel HubsB. Rear HubsC. Wheel Bearing Grease SpecificationD. Bearing Troubleshooting

ANSWERS TO TEXTBOOK REVIEW QUESTIONS

1. Wheels are constructed either from stamped or pressed steel riveted or weldedtogether or from die-cast or forged aluminum or magnesium alloy.2. Dynamic balance is described as an equal distribution of weight on each side of the

tire’s centerline. Static balance is an equal distribution of weight around the circum-ference of the tire.

3. The section of the wheel that allows the tire to be easily removed and installed is calledthe drop center.

4. A tire may be repaired using a plug that is slightly larger than the size of the punc-ture. Some plugs are inserted from inside the tire and pulled through with an instal-lation tool, while others may be installed using an installation tool without removingthe tire from the wheel. The plug is cemented in place and the excess is trimmed off,with care being taken not to pull on the plug while trimming it.

5. A bubble balancer checks the static balance of a tire.6. Underinflation can increase the rolling resistance of a tire. This results in rapid tire

wear, hard steering, squealing, and a decrease in fuel economy by as much as 10%.7. d. The series of a tire describes its profile.8. a. Belts are constructed of steel, nylon, or woven fibers.9. c. Both technicians are correct.

10. a. An overinflated tire will be worn more in the center of the tread.11. d. All of the above

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12. a. Sealant injected through the valve stem may be used to seal punctures in the treadarea.

13. c. Both technicians are correct.14. b. The tire placard contains information about the tire.15. b. Lateral runout is described as a side-to-side wobble.

16. b. Some axle nuts on FWD applications are staked in place after being torqued.17. c. Wheel balancing should be done when the tires are rotated.18. d. The bead is the portion of the tire that seals against the rim.19. c. The maximum tire pressure and maximum load information are located on the side-

wall of the tire.20. d. The tire pressure molded into the sidewall of the tire is the maximum, not the rec-

ommended, pressure.

ADDITIONAL TEACHING HINTS

Compare samples of several types of tire construction.Discuss tire/wheel runout.Discuss the importance of maintaining wheel offset when changing to sport wheels.Discuss the ratings in terms of performance and wear.Demonstrate how to properly rotate tires and torque the lug nuts.Discuss the limitations on spare tires.

ANSWERS TO TECH MANUAL REVIEW QUESTIONS

1. Provide traction2. a. directional

b. nondirectionalc. symmetrical

3. a. head-type plugb. cold patchc. hot patch

4. Axle bearings are on an axle that drives the wheels; wheel bearings are on axles thatdo not drive.

5. Record the part number of the old bearing.6. Ball or tapered-roller7. Dial indicator8. c9. a

10. b

TECH MANUAL

The following procedures are included in Chapter 42 of the Tech Manual:

1. Inspecting tires for inflation and wear.2. Removing and installing front wheel bearings on a rear-wheel-drive vehicle:3. Balancing a tire and wheel off the vehicle.

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174

CHAPTER OVERVIEW

This chapter describes various types of suspensions including torsion bar suspension, live-

axle rear suspension, independent suspension, and electronically controlled suspension.Functions of the various parts and service requirements are discussed.

CHAPTER OBJECTIVES

Name the different types of springs and how they operate.Name the advantages of ball joint suspensions.Explain the important differences between sprung and unsprung weight with regardto suspension control devices.Identify the functions of shock absorbers and struts and describe their basicconstruction.Identify the components of a MacPherson strut system and describe their functions.

Identify the functions of bushings and stabilizers.Perform a general front suspension inspection.Check chassis height measurements to specifications.Identify the three basic types of rear suspensions and know their effects on tractionand tire wear.Identify the various types of springs, their functions, and their locations in the rearaxle housing.Describe the advantages and operation of the three basic electronically controlledsuspension systems: level control, adaptive, and active.Explain the function of electronic suspension components including aircompressors, sensors, control modules, air shocks, electronic shock absorbers, andelectronic struts.Explain the basic towing, lifting, jacking, and service precautions that must befollowed when servicing air springs and other electronic suspension components.


I. FramesA. Conventional Frame ConstructionB. Unibody Construction

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II. Suspension System ComponentsA. Springs

1. Coil Springs(a) Servicing Coil Springs

2. Leaf Springs

(a) Multiple-Leaf Springs(b) Monoleaf Springs(c) Fiber Composite Springs

3. Air SpringsB. Torsion Bar Suspension SystemC. Shock Absorbers

1. Gas-Charged Shock Absorbers2. Air Shock Systems3. Shock Absorber Ratio

III. MacPherson Strut Suspension ComponentsA. StrutsB. Lower Suspension ComponentsC. Springs

IV. Independent Front SuspensionA. Short-Long Arm Suspension

1. Wheel Spindle2. Control Arms3. Ball Joints4. Other Front System Components

(a) Bushings(b) Stabilizers

B. Four-Link Front SuspensionV. General Front-Suspension Inspection

A. Chassis Height SpecificationsHint: Explain how chassis height changes over time and how this affectshandling and alignment. Explain how chassis height is restored.

VI. Front-Suspension Component ServicingA. Coil Springs

1. Removing a SpringB. Torsion BarsC. Ball Joints

1. Typical Radial Check2. Typical Axial Check3. Inspection of Wear Indicators

D. Control Arm BushingsE. Strut Rod BushingsF. Sway Bar Bushings

G. Shock AbsorbersH. MacPherson Strut SuspensionVII. Rear-Suspension Systems

A. Live Axle Rear-Suspension Systems1. Leaf Spring Live-Axle System2. Coil Spring Live-Axle System3. Live-Axle Suspension System Servicing

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VIII. Semi-Independent SuspensionA. Semi-Independent Suspension System Servicing

IX. Independent SuspensionA. Multilink Rear SuspensionB. Servicing Independent Suspension Systems

1. Servicing Rear Coil Spring2. Servicing Rear Control ArmsX. Electronically Controlled Suspensions

Hint: Discuss the advantages gained with adaptive and active suspensionsystems.A. Adaptive Suspensions

1. System Components(a) Compressor(b) Sensors(c) Electronic Shock Absorbers(d) Electronic Struts(e) Computer Control Module(f) Electronic Leveling Control

2. Adjustable Pneumatic SuspensionB. MagneRide

XI. Servicing Electronic Suspension ComponentsA. Wheel Alignment

XII. Active SuspensionsA. Chassis Lubrication


1. A stabilizer bar is sometimes referred to as a sway bar. It stabilizes the suspension sys-tem by transferring the movement of one wheel over to the opposite wheel to create

a more level ride.2. Sprung weight consists of all of the weight of the vehicle supported by the suspension

system. Unsprung weight includes undercar components such as the axles, controlarms, and steering knuckles that are not supported by the springs. A low ratio of unsprung weight is desirable for better ride quality.

3. An air spring operates on the principle that as a bag filled with compressed air is com-pressed, pressure in the bag increases. Increasingly more force is required to accom-plish additional compression of the bag. In this way, an air spring functions as avariable rate spring and replaces conventional springs.

4. A conventional shock absorber dampens suspension movement by operating on theprinciple of fluid displacement through an orifice. It is a velocity-sensitive hydraulicdampening device. The faster it moves, the more resistance it has to movement. Kinet-

ic energy (energy of motion) is converted to heat and dissipated to the atmosphere.As the rod of the shock absorber is forced inward during the compression cycle, ithelps control the vehicle’s sprung weight. During the extension cycle, when the rodis pulled outward, it controls the unsprung weight. A typical shock absorber isdesigned to have a higher ratio of resistance during its extension cycle.

5. An independent suspension system allows each wheel to move independently inresponse to inputs from the road surface, braking torque, and body motion withoutaffecting the other wheels.

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6. b. The core of any suspension system is the spring.7. d. When the wheel moves downward from the frame it is called rebound.8. c. The steering linkage and the tires are part of the unsprung weight; the engine is

part of the sprung weight of the vehicle.9. a. When the wheel hits a bump and moves upward, it is called jounce.

10. b. Follower ball joints should be replaced when any perceptible play is found. Load-carrying ball joints will have zero play until they begin to wear and are not replaceduntil they exceed the wear limits.

11. c. Both technicians are correct.12. b. The shock absorbers dampen or control the motion of the vehicle.13. a. The coil springs of the vehicle support its weight.14. b. The amount of fuel in the tank affects the ride height of a vehicle.15. d. Neither technician is correct. It is the shock absorbers that are designed to limit

wheel tramp among other things. Leaf-spring-type rear axle suspensions are subjectto axle tramp, not wheel tramp.

16. d. SLA suspension systems may use a single or a double control arm design.17. c. While most strut suspension systems use coil springs, the Chapman strut may use

leaf springs.18. a. This describes a trailing arm.19. a. The modified MacPherson strut rear suspension is very common in front-wheel-

drive vehicles.20. c. Both technicians are correct.


Display and discuss several types of shock absorbers, including worn ones.Examine and discuss the components of a front strut.Perform a general front-suspension inspection using guidelines and the servicemanual.Replace ball joints on a vehicle.


1. a. coilb. leaf c. torsion bar

2. c

TECH MANUAL


1. Inspecting suspension components.2. Removing a strut assembly.3. Replacing the cartridge in a strut assembly.4. Removing and installing control arm bushings on a rear coil-spring-type suspension

system.

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3. a4. c5. To the left6. The shock absorber contains oil that contacts and lubricates the inner wall of the strut

body.

7. Ball joints8. Precise wheel alignment settings or angles9. a. difficult steering and handling

b. braking not smoothc. excessive bouncing after stops

10. c

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179

CHAPTER OVERVIEW

This chapter discusses manual, power-, and four-wheel steering system theory, operation,and components in depth.

CHAPTER OBJECTIVESDescribe the similarities and differences between parallelogram, worm and roller,and rack and pinion steering linkage systems.Identify the typical manual-steering system components and their functions.Name the five basic types of steering linkage systems.Identify the components in a parallelogram steering linkage arrangement anddescribe the function of each.Identify the components in a manual rack and pinion steering arrangement anddescribe the function of each.Describe the function and operation of a manual-steering gearbox and the steeringcolumn.Explain the various manual-steering service procedures.Describe the service to the various power-steering designs.Perform general power-steering system checks.Describe the common four-wheel steering systems.


I. Manual-Steering SystemsHint: Have students give the correct name for common steering systems partsfrom looking at several vehicles or by the use of a parts identification board.A. Steering LinkageB. Parallelogram Steering Linkage

1. Pitman Arm2. Idler Arm3. Links4. Tie Rods

C. Rack and Pinion Steering Linkage1. Rack

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2. Pinion3. Yoke adjustment4. Tie Rods

D. Manual-Steering GearHint: Demonstrate the correct way to adjust gear lash.

E. Steering Wheel and ColumnF. Steering DamperII. Power-Steering Systems

A. Integral Piston SystemB. Power Assisted Rack and Pinion SystemC. Components

1. Power-Steering Fluid2. Power-Steering Pump3. Power-Steering Pump Drive Belts4. Electronic Power-Steering Motors5. Flow Control and Pressure Relief Valves6. Power-Steering Gearbox

Hint: Demonstrate the correct way to adjust preload and gear lash.7. Power-Assisted Rack and Pinion Steering8. Power-Steering Hoses

III. Electronically Controlled Power-Steering SystemsA. Active SteeringB. General ServiceC. Electric/Electronic Rack and Pinion System

IV. Steering System DiagnosisA. Common Complaints

1. Excessive Steering-Wheel Play2. Feedback3. Hard Steering4. Nibble5. Pulling or Drifting6. Shimmy7. Sticking Steering or Poor Return8. Wandering9. Noise

B. DiagnosingC. Power-Steering Pressure Checks

V. Visual InspectionHint: Demonstrate a prealignment inspection.A. Power-Steering Pump BeltB. Pitman ArmC. Idler ArmD. Center Link

E. Tie-Rod AssemblyF. Steering DamperG. Dry Park CheckH. Turning EffortI. Tie-Rod Articulation EffortJ. Worm and Roller SteeringK. Rack and Pinion Steering

VI. Steering System ServicingA. Steering Gear Adjustments

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B. Steering ColumnsVII. Power-Steering System Servicing

A. Flushing the SystemVIII. Four-Wheel Steering Systems

A. Mechanical 4WS

B. Hydraulic 4WSC. Electro/Hydraulic 4WSD. Quadrasteer


1. A parallelogram steering arrangement using either a recirculating ball or worm androller steering gearbox uses a pitman arm to connect to the steering linkage. The pit-man arm transfers motion from the steering gearbox to the linkage, causing the wheelsto turn in the correct direction. A rack and pinion steering arrangement has a smallpinion gear attached to the end of the steering column that moves a toothed rackattached directly to the tie rods. Movement of the pinion gear causes the rack to pushand pull the tie rods and moves the wheels in the desired direction.

2. A power-steering hose transmits fluid under pressure from the pump to the steeringgearbox.

3. An integral power-steering system consists of a power-steering pump and reservoir,power-steering pressure and return hoses, and a power-steering gear (gearbox). Thepower-steering gear contains a power piston and control valves to assist in turningthe wheels in both directions.

4. The term gearbox ratio refers to the number of input turns required to produce oneoutput turn.

5. All-wheel steering reduces the tendency of production-built cars to either oversteeror understeer, producing near neutral steering under varying road conditions. Theadvantages gained are increased stability, cornering, and maneuverability.

6. c. Power-steering hoses transmit fluid under pressure.7. c. Both technicians are correct.8. b. A shimmy is more likely to be the result of looseness in the steering linkage. Faults

in a manual steering gear would cause other symptoms.9. c. Both technicians are correct.

10. c. Both technicians are correct.11. a. Worn tie-rod ends can result in scalloped and scuffed tires.12. d. The bellows boot protects the rack from contamination.13. b. Variable ratio is normally used only in power-steering units.14. a. Binding steering column U-joints are not a probable cause of wheel shimmy.15. b. The idler arm supports the right side of the center link and keeps the center link

level, but it does not keep the steering system level.16. b. A pull scale may be used to check steering effort. A misaligned frame would most

likely cause concerns other than excessive turning effort, such as dog-tracking or tirewear.17. c. In a linkage-type power-steering system the power cylinder is attached to the center

link. Two hydraulic hoses are attached to the power cylinder and two lines are con-nected to the control valve.

18. c. Contra phase four-wheel steering is turning the rear wheels in an opposite direc-tion to the front wheels, greatly reducing the vehicle turning circle.

19. a. Rack and pinion steering is lighter and has fewer components.20. b. The steering linkage connects the steering column to the wheels.

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Display and discuss several types of steering components, including worn ones.Examine and discuss the components of a worm and roller steering system.Examine and discuss the components of a rack and pinion steering system.

Demonstrate the dry park check method for checking steering systems.


1. a. rack and pinionb. worm and rollerc. recirculating ball

2. Dry park3. Pull scale4. True5. a. Always wear safety glasses when repairing an air bag system or when handling an

air bag module.

b. To prevent accidental deployment and possible injury, the backup power supplyfor the air bag must be depleted before replacing an air bag and before servicing,replacing, adjusting, or striking components close to the air bag sensor.c. To deplete backup power supply, disconnect the ground cable of the battery andwait at least one minute (some manufacturers recommend a longer waiting period).d. Refer to the appropriate service manual to identify the location of the air bag sensors.e. Never probe the connectors on the air bag module because doing so can cause acci-dental deployment.f. Carry a live air bag module with the air bag and trim cover pointed away from yourbody.g. Never set a live air bag module down with the trim cover face down.h. If a vehicle with an air bag was involved in an accident, inspect its sensor mount-ing bracket and wiring harness for damage. Replace any damaged parts.i. After deployment of an air bag, the bag and the surrounding surfaces may containsodium hydroxide, which is a skin irritant. Wash your hands with soap and water afterworking around the air bag.

6. c7. b8. d9. a

10. c

TECH MANUAL


1. Diagnosing, removing, and replacing an idler arm.

2. Removing and replacing an outer tie-rod end on a parallelogram steering linkage system.3. Flushing a power-steering system.4. Testing the pressure of a power-steering pump system.5. Inspecting a rack and pinion steering gear.

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183

CHAPTER OVERVIEW

This chapter discusses the theory and importance of proper two- and four-wheel alignment.Alignment equipment and tools are described.

CHAPTER OBJECTIVES

Explain the benefits of accurate wheel alignment.Explain the importance of correct wheel alignment angles.Describe the different functions of camber and caster with regard to the vehicle’ssuspension.Identify the purposes of steering axis inclination.Explain why toe is the most critical tire wear factor of all the alignment angles.Identify the purposes of turning radius or toe-out.Explain the condition known as tracking.Perform a prealignment inspection.Describe the various types of equipment that can be used to align the wheels of a vehicle.Describe how alignment angles can be changed on a vehicle.Understand the importance of rear-wheel alignment.Know the difference between two-wheel and four-wheel alignment procedures.


I. Alignment GeometryA. Caster

Hint: Use a steering knuckle that has been removed to show the arc traveledby the end of the spindle when the wheels are turned by simulating bothpositive and negative caster. Also show how tipping the steering knuckle toprovide positive camber places the load on the inboard area of the spindle.

B. CamberC. ToeD. Thrust Line Alignment

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E. Steering Axis Inclination (SAI)F. Turning RadiusG. TrackingH. Load Distribution

II. Prealignment Inspection

Hint: Demonstrate a prealignment inspection.III. Wheel Alignment EquipmentA. Turning Radius GaugesB. Caster-Camber GaugeC. Optical Toe GaugesD. Trammel Bar GaugeE. Miscellaneous Tools

IV. Alignment MachinesV. Adjusting Wheel Alignment

A. Caster/Camber Adjustment1. Shims2. Eccentrics and Shims3. Slotted Frame4. Rotating Ball Joint and Washers

B. MacPherson Suspension AdjustmentsC. Rear-Wheel Camber AdjustmentsD. Toe Adjustment

1. Rear Toe2. Thrust Line

VI. Four-Wheel-Drive Vehicle Alignment


1. Positive camber is the angle represented by the tilt of either the front or rear wheels

outward from true vertical as viewed from the front of the car.2. Excessive negative camber causes the portion of the tread toward the centerline of thecar to wear.

3. Excessive negative caster can cause wandering, unintentional weaving, and instabil-ity at higher speeds.

4. Toe is the distance comparison between the leading edge and trailing edge of the tires.If the leading edge distance is less than the trailing edge, there is toe-in; if it is greater,there is toe-out.

5. The difference between rear toe and the geometric centerline of the vehicle is calledthe thrust angle. The vehicle tends to travel in the direction of the thrust line ratherthan straight ahead.

6. Excessive toe-out can cause the car to wander and lose stability on slick surfacesbecause the tire is partially sliding, rather than rolling, on the road surface.

7. The bottom of the tire and wheel assembly must be moved inward in order to addmore positive camber.

8. Toe-out on turns is provided by the angles designed into the steering arm.9. c. SAI is the angle formed between true vertical and a line drawn between the steer-

ing pivot points as viewed from the front.10. During a four-wheel alignment, adjustments should be made in this order: (1) rear

camber, (2) rear toe, (3) front caster, (4) front camber, and (5) front toe.

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11. Caster may be checked using a caster-camber bubble gauge and the protractor scaleon the alignment equipment’s turntables. When this gauge is used it is normallyattached to a machined surface of the hub by a strong magnet. After the suspensionhas been stabilized by jouncing and camber has been read and recorded, caster maybe measured. Apply and hold the brakes applied with a brake pedal lock. Turn one

wheel 20° outward and adjust the bubble gauge to zero, then turn the wheel inward20° and record the reading indicated by the bubble gauge. Repeat this procedure onthe other wheel.

12. Tracking is a term used to describe the direction the rear wheels would travel if unaf-fected by the front wheels.

13. The following are guidelines for a prealignment inspection:a. Begin with a road test. While driving the car, check to see that the steering wheelis straight. Feel for vibration in the steering wheel as well as in the floor and seats.Notice any pulling or abnormal handling problems, such as hard steering, tire squealwhile cornering, or mechanical pops or clunks.b. Carefully inspect the tire wear patterns and for mismatched tire sizes or types.Check the tires’ inflation and correct if necessary. Also look for the results of collisiondamage or towing damage.c. Check the tires and wheels for radial runout.d. Check the wheel bearings.e. Remove heavy items from the trunk and passenger compartment. However, if theseitems, such as toolboxes, are normally carried in the vehicle, leave them in.f. Check the vehicle’s ride height. Every vehicle is designed to ride at a specific curbheight. Curb height specifications and the specific measuring points are given in ser-vice manuals. Proper alignment is impossible if the ride height is incorrect.g. Check the play of the steering wheel.h. Jounce the vehicle to check the condition of the shock absorbers.i. With the vehicle raised, inspect all steering and suspension components such ascontrol arm bushings, upper strut mounts, pitman arm, idler arm, center link, tie-rodends, ball joints, and shock absorbers. Check the CV joints (if equipped) for loose-ness, popping sounds, binding, and broken boots. Damaged components must berepaired before adjusting alignment angles.

14. a. Positive caster provides directional stability.15. d. the steering wheel lock centers the steering wheel during alignment. If the toe is

adjusted, the steering wheel may not be centered after alignment and a recenteringprocedure is then required.

16. c. Both technicians are correct.17. c. Both technicians are correct.18. d. Steering axis inclination is not adjusted during an alignment.19. d. Neither technician is correct.20. b. When camber is unequal, the vehicle will tend to pull toward the side with the

most positive camber.

TECH MANUAL


1. Measuring front and rear wheel alignment angles with a computer-based wheel aligner.2. Centering a steering wheel.

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Demonstrate how to do a prealignment inspection.Demonstrate how to read tire wear in terms of alignment problems.Demonstrate how to adjust camber and caster.

Demonstrate how to adjust front wheel toe-in.Demonstrate how to adjust camber, caster, and toe on rear wheels.


1. a. greater safetyb. longer tire lifec. reduced fuel consumption

2. Toe adjustments3. On the tie-rod ends4. By installing an aftermarket caster adjustment kit, repositioning the upper strut mount,

or replacing the strut assembly

5. True6. c7. c8. c9. a

10. Equal camber means each wheel is tilted outward or inward the same amount.

SECTION 7

Answers to ASE Prep Questions

1. c 6. c 11. b 16. d 21. c2. c 7. a 12. c 17. c 22. c3. b 8. c 13. a 18. c 23. c4. b 9. c 14. d 19. c 24. c5. d 10. b 15. b 20. b 25. b

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