AutoCAD Architecture 2008: Part I: Getting Started

CHAPTER 17 Wheel Alignment Principles OBJECTIVES After studying Chapter 17, the reader will be able to: 1. 2. 3. 4. Prepare for ASE Suspension and Steering (A4) certification test content area D (Wheel Alignment Diagnosis, Adjustment, and Repair). Discuss which vehicle handling problems can and cannot be corrected by an alignment. Define camber, toe, caster, SAI, included angle, scrub radius, turning radius, setback, and thrust

line. Explain how camber, caster, and toe affect the handling and tire wear of the vehicle. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 2 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. KEY TERMS

BJI Camber Camber roll Caster Dog tracking Drift Four-wheel alignment Included angle KPI Lead MSI Pull

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 3 Returnability Road crown

SAI Scrub radius Setback Shimmy Steering dampener Steering offset Thrust line Toe TOOT Tramp Wander Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. DEFINITION OF A WHEEL ALIGNMENT

A wheel alignment is the adjustment of the suspension and steering to ensure proper vehicle handling with minimum tire wear. When a vehicle is new, the alignment angles are set at the factory. After many miles and/or months of driving, the alignment angles can change slightly. The change in alignment angles may result from one or more of the following conditions: Wear of the steering and the suspension components Bent or damaged steering and suspension parts Sagging springs, which can change the ride height of the vehicle and therefore the alignment angles

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 4 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS Most alignment diagnosis is symptom-based diagnosis. This means that the problem with the alignment is determined from symptoms such as excessive tire wear or a pull to one side of the road.

PULL LEAD OR DRIFT ROAD CROWN EFFECTS WANDER STIFF STEERING OR SLOW RETURN TO CENTER TRAMP OR SHIMMY VIBRATION CAMBER Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 5 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved.

ALIGNMENT-RELATED PROBLEMS FIGURE 171 A pull is usually defined as a tug on the steering wheel toward one side or the other. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 6 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 172 The crown of the road refers to the angle or slope of the roadway needed to drain water off the pavement. (Courtesy of Hunter Engineering Company) Automotive Steering, Suspension and Alignment, 5/e

By James D. Halderman 7 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 173 Wander is an unstable condition requiring constant driver corrections. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 8 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS

FIGURE 174 Positive camber. The solid vertical line represents true vertical, and the dotted line represents the angle of the tire. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 9 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 175 Negative camber. The solid vertical line represents true vertical, and the dotted line represents the angle of the tire.

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 10 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 176 Zero camber. Note that the angle of the tire is true vertical. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 11

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 177 Excessive positive camber and how the front tires would wear due to the excessive camber. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 12 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 178 Excessive negative camber and how the front tires would wear due to the excessive camber.

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 13 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 179 Positive camber tilts the tire and forms a cone shape that causes the wheel to roll away or pull outward toward the point of the cone. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 14 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc.,

Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 1710 Negative camber creates a pulling force toward the center of the vehicle. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 15 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 1711 If camber angles are different from one side to the other, the vehicle will pull toward the side with the most camber.

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 16 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 1712 Positive camber applies the vehicle weight toward the larger inner wheel bearing. This is desirable because the larger inner bearing is designed to carry more vehicle weight than the smaller outer bearing. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

17 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. ALIGNMENT-RELATED PROBLEMS FIGURE 1713 Negative camber applies the vehicle weight to the smaller outer wheel bearing. Excessive negative camber, therefore, may contribute to outer wheel bearing failure. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 18 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc.,

Upper Saddle River, NJ 07458 All rights reserved. CASTER Caster is the forward or rearward tilt of the steering axis in reference to a vertical line as viewed from the side of the vehicle. The steering axis is defined as the line drawn through the upper and lower steering pivot points. On an SLA suspension system, the upper pivot is the upper ball joint and the lower pivot is the lower ball joint.

On a MacPherson strut system, the upper pivot is the center of the upper bearing mount and the lower pivot point is the lower ball joint. Zero caster means that the steering axis is straight up and down, also called 0 degrees or perfectly Vertical. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 19 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CASTER FIGURE 1715 Positive (+) caster. FIGURE 1714 Zero caster.

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 20 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CASTER FIGURE 1716 Negative (-) caster is seldom specified on todays vehicles because it tends to make the vehicle unstable at highway speeds. Negative caster was specified on some older vehicles not equipped with power steering to help reduce the steering effort. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

FIGURE 1717 As the spindle rotates, it lifts the weight of the vehicle due to the angle of the steering axis. (Courtesy of Hunter Engineering Company) 21 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CASTER FIGURE 1718 Vehicle weight tends to lower the spindle, which returns the steering to the straightahead position. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman FIGURE 1719 High caster provides a road shock

path to the vehicle. 22 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CASTER FIGURE 1720 A steering dampener is used on many pickup trucks, sport utility vehicles (SUVs), and many luxury vehicles designed with a high-positive-caster setting. The dampener helps prevent steering wheel kickback when the front tires hit a bump or hole in the road and also helps reduce steering wheel shimmy that may result from the high-caster setting. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 23

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CASTER FIGURE 1721 As the load increases in the rear of a vehicle, the top steering axis pivot point moves rearward, increasing positive (+) caster. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 24 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. Caster Angle Tire Wear

The caster angle is generally considered to be a nontire-wearing angle. However, excessive or unequal caster can indirectly cause tire wear. When the front wheels are turned on a vehicle with a lot of positive caster, they become angled. This is called camber roll. (Caster angle is a measurement of the difference in camber angle from when the wheel is turned inward compared to when the wheel is turned outward.) Most vehicle manufacturers have positive caster designed into the suspension system. This positive caster increases the directional stability. However, if the vehicle is used exclusively in city driving, positive caster can cause tire wear to the outside shoulders of both front tires. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 25

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. Caster Angle Tire Wear FIGURE 1722 Note how the front tire becomes tilted as the vehicle turns a corner with positive caster. The higher the caster angle, the more the front tires tilt, causing camber-type tire wear. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 26 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE

Toe is the difference in distance between the front and rear of the tires. Toe is the most important of the alignment angles. As viewed from the top of the vehicle (a birds eye view), zero toe means that both wheels on the same axle are parallel. Toe is also described as a comparison of horizontal lines drawn through both wheels on the same axle. If the front of the tires is closer than the rear of the same tires, then the toe is called toe-in or positive (+) toe.

If the front of the tires is farther apart than the rear of the same tires, then the wheels are toed-out, or have negative (-) toe. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 27 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1723 Zero toe. Note how both tires are parallel to each other as viewed from above the vehicle. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

28 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1724 Total toe is often expressed as an angle. Because both front wheels are tied together through the tie rods and center link, the toe angle is always equally split between the two front wheels when the vehicle moves forward. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 29 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE

FIGURE 1726 Toe-out, also called negative (-) toe. (Courtesy of Hunter Engineering Company) FIGURE 1725 Toe-in, also called positive (+) toe. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 30 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1727 This tire is just one month old! It was new and installed on the front of a vehicle that had about 1/4 inch (6 mm) of toe-out. By

the time the customer returned to the tire store for an alignment, the tire was completely bald on the inside. Note the almost new tread on the outside. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 31 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1728 Excessive toe-out and the type of wear that can occur to the side of both front tires. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

32 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1729 Excessive toe-in and the type of wear that can occur to the outside of both front tires. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 33 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE

FIGURE 1730 Feather-edge wear pattern caused by excessive toe-in or toe-out. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 34 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1731 Rear toe-in (+). The rear toe (unlike the front toe) can be different for each wheel while the vehicle is moving forward because the rear wheels are not tied together as they are in the front. (Courtesy of Hunter Engineering Company) Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

35 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1732 Incorrect toe can cause the tire to run sideways as it rolls, resulting in a diagonal wipe. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 36 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved.

TOE FIGURE 1733 Diagonal wear such as shown here is usually caused by incorrect toe on the rear of a front-wheel-drive vehicle. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 37 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TOE FIGURE 1734 Toe on the front of most vehicles is adjusted by turning the tie rod sleeve as shown. (Courtesy of John Bean Company)

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 38 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. Why Doesnt Unequal Front Toe on the Front Wheels Cause the Vehicle to Pull? Each wheel could have individual toe, but as the vehicle is being driven, the forces on the tires tend to split the toe, causing the steering wheel to cock at an angle as the front wheels both track the same. If the toe is different on the rear of the vehicle, the rear will be steered similar to a rudder on a boat

because the rear wheels are not tied together as are the front wheels. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 39 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. Smooth In, Toed-In; Smooth Out, ToedOut Whenever the toe setting is not zero, a rubbing action occurs that causes a feather-edge-type wear. A quick, easy method to determine if incorrect toe could be causing problems is simply to rub your hand across the tread of the tire. If it feels smoother moving your

hand toward the center of the vehicle than when you move your hand toward the outside, then the cause is excessive toein. The opposite effect is caused by toeout. This may be felt on all types of tires, including radial-ply tires where the wear may not be seen as feather edged. Just remember this simple saying: Smooth in, toed-in; smooth out, toed-out. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 40 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. Smooth In, Toed-In; Smooth Out, ToedOut FIGURE 1735 While the feathered or sawtooth tire tread wear pattern may not be noticeable to the eye, this wear

can usually be felt by rubbing your hand across the tread of the tire. (Courtesy of John Bean Company) Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 41 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. STEERING AXIS INCLINATION (SAI)

The steering axis is the angle formed between true vertical and an imaginary line drawn between the upper and lower pivot points of the spindle. Steering axis inclination (SAI) is the inward tilt of the steering axis. SAI is also known as kingpin inclination (KPI) and is the imaginary line drawn through the kingpin as viewed from the front. SAI is also called ball joint inclination (BJI), if SLA-type suspension is used, or MacPherson strut inclination (MSI). Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 42 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved.

STEERING AXIS INCLINATION (SAI) FIGURE 1736 The left illustration shows that the steering axis inclination angle is determined by drawing a line through the center of the upper and lower ball joints. This represents the pivot points of the front wheels when the steering wheel is rotated during cornering. The right illustration shows that the steering axis inclination angle is determined by drawing a line through the axis of the upper strut bearing mount assembly and the lower ball joint. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 43 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. STEERING AXIS INCLINATION (SAI) FIGURE 1737 The SAI causes the spindle to travel in an arc when the wheels are turned. The weight of the vehicle is therefore used to help

straighten the front tires after a turn and to help give directional stability. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 44 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. INCLUDED ANGLE The included angle is the SAI added to the camber reading of the front wheels only. The included angle is determined by the design

of the steering knuckle, or strut construction. FIGURE 1738 Included angle on a MacPhersonstrut-type suspension. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 45 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. INCLUDED ANGLE FIGURE 1739 Included angle on an SLA-type suspension. The included angle is the SAI angle and the camber angle added together.

Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 46 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. INCLUDED ANGLE FIGURE 1740 Cradle placement. If the cradle is not replaced in the exact position after removal for a transmission or clutch replacement, the SAI, camber, and included angle will not be equal side-to-side. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 47 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc.,

Upper Saddle River, NJ 07458 All rights reserved. SCRUB RADIUS Scrub radius refers to the distance between the line through the steering axis and the centerline of the wheel at the contact point with the road surface. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 48 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SCRUB RADIUS

FIGURE 1741 A positive scrub radius (angle) is usually built into most SLA front suspensions, and a negative scrub radius is usually built into most MacPhersonstrut- type front suspensions. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 49 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SCRUB RADIUS FIGURE 1742 With negative scrub radius, the imaginary line through the steering axis inclination (SAI) intersects the road outside of the centerline of the tire. With positive scrub radius, the SAI line intersects the road inside the centerline of the tires. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 50

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SCRUB RADIUS FIGURE 1743 With a positive scrub radius, the pivot point, marked with a + mark, is inside the centerline of the tire and will cause the wheel to turn toward the outside, especially during braking. Zero scrub radius does not create any force on the tires and is not usually used on vehicles because it does not create an opposing force on the tires, which in turn makes the vehicle more susceptible to minor bumps and dips in the road. Negative scrub radius, as is used with most front-wheel-drive vehicles, generates an inward force on the tires. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 51 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved.

TURNING RADIUS (TOE-OUT ON TURNS) Whenever a vehicle turns a corner, the inside wheel has to turn at a sharper angle than the outside wheel because the inside wheel has a shorter distance to travel. Turning radius is also called toe-out on turns, abbreviated TOT or TOOT, and is determined by the angle of the steering knuckle arms. Turning radius is a nonadjustable angle. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 52

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TURNING RADIUS (TOE-OUT ON TURNS) The turning radius can and should be measured as part of an alignment to check if the steering arms are bent or damaged. Symptoms of out-of-specification turning angle include the following: Tire squeal noise during normal cornering, even at low speeds

Scuffed tire wear Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 53 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TURNING RADIUS (TOE-OUT ON TURNS) FIGURE 1744 To provide handling, the inside wheel has to turn at a greater turning radius than the outside wheel. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman FIGURE 1745 The proper toe-out on turns is

achieved by angling the steering arms. 54 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SETBACK Setback is the angle formed by a line drawn perpendicular (at 90 degrees) to the front axles. Setback is a nonadjustable measurement, even though it may be corrected. Positive setback means the right front wheel is set back farther than the left; negative setback means

the left front wheel is set back farther than the right. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 55 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SETBACK FIGURE 1746 (a) Positive setback. (b) Negative setback. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 56

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SETBACK FIGURE 1747 Cradle placement affects setback. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 57 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. THRUST ANGLE

Thrust angle is the angle of the rear wheels as determined by the total rear toe. If both rear wheels have zero toe, then the thrust angle is the same as the geometric centerline of the vehicle. The total of the rear toe setting determines the thrust line, or the direction the rear wheels are pointed. On vehicles with an independent rear suspension, if both wheels do not have equal toe, the vehicle will pull in the direction of the side with the most toe-in. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

58 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. THRUST ANGLE FIGURE 1748 (a) Zero thrust angle. (b) Thrust line to the right. (c) Thrust line to the left. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 59 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. TRACKING

The rear wheels should track directly behind the front wheels. If the vehicle has been involved in an accident, it is possible that the frame or rear axle mounting could cause dog tracking. FIGURE 1749 (a) Proper tracking. (b) Front wheels steering toward thrust line. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 60

Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. FOUR-WHEEL ALIGNMENT Four-wheel alignment refers to the checking and/ or adjustment of all four wheels. Four-wheel alignment is important for proper handling and tire wear, to check the camber and the toe of the rear wheels of front-wheel-drive vehicles. Some rear-wheel-drive vehicles equipped with independent rear suspension can be adjusted for

camber and toe. Rear-wheel caster cannot be measured or adjusted because to measure caster, the wheels must be turned from straight ahead. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 61 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. FOUR-WHEEL ALIGNMENT

Since rear wheels are securely attached, a caster sweep (turning the wheels to take a caster reading) is not possible. While rear camber can cause tire wear problems, by far the greatest tire wear occurs due to toe settings. Unequal toe in the rear can cause the vehicle to pull or lead. The rear camber and toe are always adjusted first before adjusting the front caster, camber, and toe. This procedure ensures that the thrust line and centerline of the vehicle are the same. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman

62 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SUMMARY 1. 2. 3. 4. The need for a wheel alignment results from wear or damage to suspension and steering components. Camber is both a pulling angle (if not equal sideto-side) as well as a tire wearing angle (if not set to specifications). Incorrect camber can cause tire wear and pulling if

camber is not within 1/2 degree from one side to the other. Toe is the most important alignment angle because toe is usually the first requiring correction. When incorrect, toe causes severe tire wear. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 63 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. SUMMARY 5. 6.

7. 8. 9. Incorrect toe causes excessive tire wear and creates instability if not within specifications. Caster is the basic stability angle, yet it does not cause tire wear (directly) if not correct or equal side-to-side. SAI and included angle (SAI and camber added together) are important diagnostic tools. If the toe-out on turns (TOOT) reading is not within specifications, a bent steering spindle (steering knuckle) is the most likely cause. A four-wheel alignment includes aligning all four wheels of the vehicle. Automotive Steering, Suspension and Alignment, 5/e

By James D. Halderman 64 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. REVIEW QUESTIONS 1. 2. 3. 4. Explain the three basic alignment angles of camber, caster, and toe. Describe what happens to tire wear and vehicle handling if toe, camber, and caster are out of

specification or not equal side-to-side. Explain how knowing SAI, TOOT, and included angle can help in the correct diagnosis of an alignment problem. Explain what thrust angle means. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 65 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 1. When performing an alignment, which angle is the most important for tire wear? a. b. c.

d. Toe Camber Caster SAI (KPI) Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 66 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 2. Positive camber means ________. a. b. c.

d. The top of the tire is tilted outward. The top of the tire is tilted inward Either a or b Both a and b Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 67 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 3. Which alignment angle is adjustable on all vehicles? a. b.

c. d. Camber Caster Toe SAI (KPI) Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 68 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 4. Positive (+) toe is ________. a. b.

Toe-in Toe-out Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 69 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 5. If the top of the steering axis is tilted 2 degrees toward the rear of the vehicle, this is ________. a. b. c. d.

Positive camber Negative camber Negative caster Positive caster Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 70 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 6. A steering dampener may be needed to reduce shimmy on vehicles that have high positive ________. a. b. c.

d. Camber Caster Toe Included angle Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 71 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 7. If the turning radius (toe-out on turns, or TOOT) is out of specification, what part or component is defective? a.

b. c. d. The strut is bent. The steering arm is bent. The spindle is bent. The control arm is bent. Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 72 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 8. Which angle determines the thrust angle? a.

b. c. d. Front toe Rear toe Rear camber Front caster, SAI, and included angle Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 73 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 9. Included angle is ________. a.

b. c. d. SAI + caster Camber + caster Camber + SAI Toe + camber Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 74 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved. CHAPTER QUIZ 10. Two technicians are discussing scrub radius. Technician A says that scrub radius can not be

measured. Technician B says that scrub radius can not be adjusted. Which technician is correct? a. b. c. d. Technician A only Technician B only Both technician A and B Neither technician A nor B Automotive Steering, Suspension and Alignment, 5/e By James D. Halderman 75 Copyright 2010, 2008, 2004, 2000, 1995 Pearson Education, Inc., Upper Saddle River, NJ 07458 All rights reserved.

Recently Viewed Presentations

  • ISBN -13: 978-1540827685 Genre: Historical Fiction Synopsis In

    ISBN -13: 978-1540827685 Genre: Historical Fiction Synopsis In

    Fast poem. Aim to practice using noun, adjective, verbs and adjectives in a short poem. Page 11. Emily's mum takes her to buy a sketch book and some gel pens from the stationary store.
  • Test Chapters 1-5 - Lincoln High School

    Test Chapters 1-5 - Lincoln High School

    Test Chapters 1-5. Chapter 1. 1: seven properties of life ... DNA, genes, genome, negative & positive feedback. 6: classification of life (DKPCOFGS) 7: domains and kingdoms. 9: Darwin's evolution. 21: scientific theory vs hypothesis. Chapter 2. 1: matter, element,...
  • Monitoring & Evaluation of Gender and Health Learning

    Monitoring & Evaluation of Gender and Health Learning

    Because there is no single "gold standard" for measuring gender norms, gender attitudes, women's empowerment, and other aspects of gender, we often use multiple measures. Using a single measure is not possible because gender operates in multiple spheres and has...
  • Electrons in Bohr Orbits vs. Electron-cloud Orbitals Atoms

    Electrons in Bohr Orbits vs. Electron-cloud Orbitals Atoms

    The orbital diagram for . N. is . The electron configuration for N is 1s22s22p3. Note that . the number of electrons in the degenerative boxes adds up to the number in the orbital subshell. of the electron configuration.
  • Roadtrip Nation - Potomac High School

    Roadtrip Nation - Potomac High School

    Words of Roadtrip Nation. What's Your Roadtrip: A life-changing journey; to define your own Road and pursue your interests in life by seeking advice from others and looking inside yourself to figure out what you are truly passionate about.
  • Symbolism and Allegory Layers of Meaning What Symbols

    Symbolism and Allegory Layers of Meaning What Symbols

    Allegory: Split Level Stories An allegory is a story in which characters, settings and actions stand for something beyond themselves. In some types of allegories, the characters and setting represent abstract ideas of moral qualities. In other types, characters and...
  • 1 Introduction to the Programme  Michael 2 Maths

    1 Introduction to the Programme Michael 2 Maths

    Martin Greenhow (Brunel) Janet Strivens (Liverpool) Jane White (Bath) Tony Croft (Loughborough) Duncan Lawson (Coventry) CETL-MSOR Conference. Annual conference will continue for 2011 and 2012. 5th & 6th September 2011 at Coventry University.
  • Glyphosate Depletes Iron, Manganese and Zinc in Plants*

    Glyphosate Depletes Iron, Manganese and Zinc in Plants*

    Moretti. et al., Neurology . ... *Collaboration with Dr. Nancy Swanson. Glyphosate application to corn and soy, US # Adverse Reactions in VAERS. Children with Autism, US . ... Glyphosate Depletes Iron, Manganese and Zinc in Plants* Last modified by: