Transcript PPT - Amistad Tech

by
Russell Krick
Publisher
The Goodheart-Willcox Co., Inc.
Tinley Park, Illinois
© Goodheart-Willcox Co., Inc.
Permission granted to reproduce for educational use only
© Goodheart-Willcox Co., Inc.
Permission granted to reproduce for educational use only
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Wheel alignment principles
Caster
Camber
Toe
Steering axis inclination
Setback
Toe-out on turns (turning radius)
(Continued)
© Goodheart-Willcox Co., Inc.
Permission granted to reproduce for educational use only
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Tracking
Prealignment inspection
Adjusting wheel alignment
Wheel alignment tools and equipment
Alignment machines
Road test after alignment
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Permission granted to reproduce for educational use only
The main purpose of wheel alignment is
to make sure the tires roll without scuffing,
slipping, or dragging under all
operating conditions
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Permission granted to reproduce for educational use only
Alignment Angles
 Six fundamental angles are needed for
proper wheel alignment:
 caster
 camber
 toe
 steering axis inclination
 toe-out on turns (turning radius)
 tracking (thrust line)
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 Forward or rearward tilt of the steering
axis (steering knuckle) when viewed
from the side of the vehicle
 Controls the tire’s load distribution in
relation to an imaginary centerline
drawn through the spindle support
 Caster does not affect tire wear
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Caster
A shopping cart caster wheel illustrates
negative caster
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Caster
A bicycle wheel represents positive caster
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Purposes of Caster
 Aid directional control
 Cause the wheels to return to the
straight-ahead position
 Offset road crown pull (steering wheel
pull caused by the hump in the center
of the road)
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Positive Caster
 Tilts the top of the steering knuckle
toward the rear of the vehicle
 Helps keep the wheels traveling in a
straight line
 When the wheels are turned, it lifts the
vehicle
 The vehicle’s weight tends to push the
wheels back to the straight-ahead
position
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Positive Caster
More common on vehicles with power steering
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Negative Caster
 Tilts the top of the steering knuckle
toward the front of the vehicle
 The wheels will be easier to turn
 The wheels will tend to swivel and
follow imperfections in the road
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Negative Caster
May be used on vehicles with manual steering,
to ease steering effort
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Caster Measurement
Measured in degrees, from true vertical
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Caster and Road
Crown Effect
Road crown is the normal slope toward the
outer edge of the road surface
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Caster and Road
Crown Effect
 Road crown causes the weight of the vehicle
to pull the vehicle away from the center of
the road
 Caster is commonly used to offset the effect
of road crown
 The right front wheel may be set with slightly
more positive caster than the left
 the vehicle pulls toward the side with the more
negative caster
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Permission granted to reproduce for educational use only
 Inward or outward tilt of the wheel and
tire assembly when viewed from the
front of the vehicle
 Controls whether the tire tread touches
the road surface evenly
 Affects tire wear
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Permission granted to reproduce for educational use only
Purposes of Camber
 To prevent tire wear on the outer or
inner tread
 To load the larger inner wheel bearing
 To aid steering by placing the vehicle’s
weight on the inner end of the spindle
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Permission granted to reproduce for educational use only
Positive and Negative
Camber
 Positive camber
 the tops of the wheels tilt outward when
viewed from the front
 most manufacturers specify a positive
setting of about 1/4º to 1/2º
 Negative camber
 the tops of the wheels tilt inward when
viewed from the front
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Positive and Negative
Camber
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Camber Measurement
Measured in degrees, from true vertical
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 Difference in distance between the
front and rear of the left- and right-hand
wheels
 Measured in inches or millimeters
 Controls whether the wheels roll in the
direction of travel
 Affects tire wear
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Permission granted to reproduce for educational use only
Toe
Toe-in: wheels are
closer at the front
than at the rear
Toe-out: wheels are
farther apart at the
front than at the rear
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Permission granted to reproduce for educational use only
Rear-Wheel-Drive Toe
Settings
 Rolling resistance and steering system
play tend to cause toe-out when driving
 Toe-in compensates for these factors
 By adjusting the front wheels for a
slight toe-in, the wheels and tires roll
straight ahead when driving
 Typical setting:
 1/16"–1/4" (1.6 mm–6 mm)
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Permission granted to reproduce for educational use only
Front-Wheel-Drive Toe
Settings
 The front wheels are pushed forward
by engine torque, causing the wheels
and tires to toe in
 To compensate for this action, frontwheel-drive vehicles normally have the
front wheels adjusted for a slight toeout
 Typical setting:
 1/16" (1.6 mm)
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Permission granted to reproduce for educational use only
 The angle, away from the vertical,
formed by the inward tilt of the steering
axis (ball joints, king pin, or
MacPherson strut tube)
 Aids directional stability by helping the
steering wheel return to the straightahead position
 Does not affect tire wear
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Permission granted to reproduce for educational use only
Steering Axis
Inclination
If the angle is incorrect, part
replacement is needed
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 One front wheel is set farther back from
the front of the vehicle than the other
front wheel
 with positive setback, the right wheel is
farther back than the left wheel
 with negative setback, the left wheel is
farther back than the right wheel
 Excessive setback will cause pull
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Setback
 Manufacturing tolerances generally allow a
small amount of setback
 Excessive setback is usually the result of
collision damage
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 Amount the front wheels toe-out when
turning corners
 As the vehicle corners, the inside tire
must travel in a smaller radius circle
than the outside tire
 The inside wheel turns sharper than the
outside wheel
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Toe-Out
on Turns
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Toe-Out on Turns
 Eliminates tire scrubbing and squealing
by keeping the tires rolling in the right
direction during turns
 Not an adjustable angle
 If the angle is incorrect, it indicates bent
or damaged steering parts
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Permission granted to reproduce for educational use only
 Position or direction of the two front
wheels in relation to the two rear
wheels
 With the proper tracking, the rear tires
follow in the tracks of the front tires
 With improper tracking, the rear tires do
not follow the tracks of the front tires
 increased tire wear, lower fuel economy,
and handling problems can result
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Permission granted to reproduce for educational use only
Tracking
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 Before attempting wheel alignment,
make sure all steering-related and
suspension-related parts are in good
condition
 It is impossible to properly align the
wheels on a vehicle with worn or
damaged parts
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Permission granted to reproduce for educational use only
Prealignment
Inspection Points
 Check for the following:
 loose wheel bearings
 wheel or tire runout
 worn tires
 tires of different sizes and types
 incorrect tire inflation
 worn steering or suspension components
 incorrect curb height and weight
 incorrect cradle alignment
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Reading Tire Wear
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Cradle Alignment
 The cradle is the strong metal structure
bolted to the frame rails on the body
 holds the lower control arms, steering
rack, and engine in alignment in the body
 Loosening and moving the cradle can
alter alignment
 Alignment holes may be provided in the
cradle and body to assure proper
alignment
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Permission granted to reproduce for educational use only
Caster, camber, and toe are the three
commonly adjustable wheel
alignment angles
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Caster and
Camber
Adjustment
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Caster and
Camber
Adjustment
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Toe Adjustment
Changing the tie-rod
length on a
rack-and-pinion unit
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Toe Adjustment
Changing the tie-rod length on
a linkage-type steering system
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Centering Steering
Wheel
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Adjusting Rear Wheel
Alignment
 Some vehicles have provisions for rear
wheel alignment
 Rear wheel alignment problems can
occur due to component wear or
damage
 Procedures for rear wheel adjustment
vary
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Permission granted to reproduce for educational use only
Adjusting
Rear Wheel
Alignment
On this axle, shim
placement changes
alignment angles
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 Various equipment and special tools
are needed
 The most basic equipment includes the
turning radius gauge, the castercamber gauge, and the tram gauge
 Alignment racks integrate the functions
of all these gauges into one machine
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Wheel Alignment Tools
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Wheel
Alignment
Tools
A. Steering wheel
lock
B. Brake pedal
depressor
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Turning Radius
Gauges
 Measure how many degrees the front
wheels are turned right or left
 Commonly used when measuring
caster, camber, and toe-out on turns
 The gauges may be portable or
mounted on the alignment rack
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Permission granted to reproduce for educational use only
Using Turning Radius
Gauges
 Center the front wheels of the vehicle
on the turning radius gauges
 Pull out the locking pins so the gauge
and tire turn together
 The pointer on the gauge will indicate
how many degrees the wheels have
been turned
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Permission granted to reproduce for educational use only
Checking Toe-Out on
Turns
 Center the front wheels of the vehicle
on the turning radius gauges
 Turn one of the front wheels until the
gauge reads 20º
 Read the number of degrees showing
on the other gauge
 Check both the right and left sides
 both sides must be within specs
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Permission granted to reproduce for educational use only
Caster-Camber
Gauges
 Used with the turning radius gauge to
measure caster and camber in degrees
 Secured on the wheel hub magnetically
or fastened on the wheel rim
 Caster and camber are adjusted
together since one adjustment may
affect the other
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Caster-Camber Gauge
Mounting
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Tram Gauges
Used to compare the distance between
the front and rear of a vehicle’s tires for
checking toe adjustment
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 The alignment machine consists of a
rack, console, and related parts
 Rack
 consists of a lift, turning radius gauges,
and equipment for measuring alignment
angles
 Console
 consists of a color monitor, keypad, and
computer
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Alignment Machine
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Console
This console provides
training, instructions,
specifications, and
feedback when doing
wheel alignment
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Software
 Alignment equipment software contains
computer instructions, equipment
operating instructions, and alignment
specifications
 When installed in the computer, the
software will help you adjust all
alignment angles quickly and easily
 Usually stored on a CD-ROM
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Permission granted to reproduce for educational use only
Alignment Heads
 Mount on the vehicle’s wheels
 Brackets are used for mounting the
alignment heads on the wheels
 Use lasers or proximity sensors to
compare the alignment of each wheel
 Used to check caster, camber, and toe
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Alignment Head
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Using Alignment
Equipment
 Always follow the operating instructions
provided by the manufacturer
 Drive the vehicle up on the lift
 Carefully center the front tires on the
turning radius gauges
 Block the rear wheels
 Mount the alignment heads on the
wheels
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Permission granted to reproduce for educational use only
Using Alignment
Equipment
 Turn on the alignment console
 Follow the computer prompts
 After you identify the vehicle, the
computer will retrieve stored data
about performing an alignment on the
vehicle
 As you make adjustments, the
equipment will monitor the changes in
the alignment angles
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Using
Alignment
Equipment
This technician is
using a four-wheel
alignment machine
with a color monitor
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Using Alignment
Equipment
This monitor is displaying alignment
angles with instructions for adjustment
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 Always road test the vehicle to check
your work
 Drive on level pavement
 Check the steering wheel alignment
 Feel for steering wheel pull
 Check for other problems, such as
noise or vibration
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Noise and Vibration
Diagnosis Chart
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