Transcript Training - Faribault Public Schools

Automotive Alignment Angles
Camber
Caster
Front toe
Rear toe
Courtesy of Hunter Engineering Company
Primary Alignment Angles
Front
Camber
Rear Camber
Caster
Front Toe
Rear Toe
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Camber
 Definition:
– The inward or outward tilt of the top of
the wheel as viewed from the front.
Typical Range:
– Front camber
– Rear camber
-
0º ± 1º
-.5 º ± 1 º
Courtesy of Hunter Engineering Company
Zero Camber
 Wheel
is vertical
when viewed from
the front
 Measured
degrees
as Zero
 Applicable
to front
and rear tires
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Reasons to use at or near
Zero Camber
 Extremely
wide tires
 Positive
offset
rims
 Extended
Tire life
Courtesy of Hunter Engineering Company
Positive Camber

Top of tire leans
outboard at the
top when viewed
from the front

Measured in
degrees

Primarily used on
front wheels
Courtesy of Hunter Engineering Company
Reasons to use Positive Camber
 Places
load inboard
on spindle
 Increases
road
 Increases
directional
isolation
stability
Courtesy of Hunter Engineering Company
Negative Camber

Top of tire leans
inboard at the top
when viewed from
the front

Measured in
degrees

Primarily used on
rear wheels
Courtesy of Hunter Engineering Company
Reasons to use Negative Camber
 Places
load outboard
on spindle
 Increased
ability
cornering
 Increases
road shock
& component wear
Courtesy of Hunter Engineering Company
Outside Shoulder Wear due to Excessive
Positive Camber Angle
Courtesy of Hunter Engineering Company
Camber may cause a Pull
 Cross
camber is the side-to-side
difference in camber
measurements
 More
than 1/2º difference side-to
side may cause the vehicle to pull
to the wheel with the most positive
camber.
Courtesy of Hunter Engineering Company
Excessive Cross Camber
0º camber
1º camber
Vehicle may pull to side of most positive camber
Courtesy of Hunter Engineering Company
Camber Specifications
 Preferred
Specs
Front = 0º
Rear = -.40º
 Tolerance
Front = 1º
Rear = .75º
 Cross camber
.70º
Courtesy of Hunter Engineering Company
Exception to the rule
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Caster
Front
 The
Forward or Rearward Tilt of
the Steering Axis as viewed from
the side
1º to 6 º positive
Typical Range
 Typical
tolerance
± 1º
Courtesy of Hunter Engineering Company
Steering Axis
Line drawn between
the two pivot points
of the steering knuckle
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Zero Caster
 Steering
Axis is
vertical as
viewed from the
side and
measured as 0º
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Negative Caster
 Forward
tilt of the
Steering Axis as
viewed from the
side and
measured in
degrees
Front
Courtesy of Hunter Engineering Company
Positive Caster

Rearward tilt of
the Steering Axis
as viewed from
the side and
measured in
degrees
Front
Courtesy of Hunter Engineering Company
Benefits of Positive Caster
 Helps
to return wheels to straight
ahead after being steered
 Helps to maintain directional
stability
Weight must be
picked up as
spindle turns
downward ….
Courtesy of Hunter Engineering Company
Negative effects of Excessive
Positive Caster
 Excessive
steering effort & road shock
 Shimmy due to excessive speed of wheels
returning to center
 Steering damper used to control speed of
steered wheels returning to center
Dampner
Courtesy of Hunter Engineering Company
Caster Measurement
 The
amount of
camber change
during a 10 steer
to the left & right
Courtesy of Hunter Engineering Company
Tire wear factor of Caster
 Tires
may show wear on both outer
edges due to camber roll.
 Camber
roll - the change in
camber during a turn due to caster
 The
amount of camber change is
relative to the amount of positive
caster
Courtesy of Hunter Engineering Company
Camber Roll
 Left
spindle
down right
spindle up
 Left
spindle
up - right
spindle
down
Courtesy of Hunter Engineering Company
Caster may cause a Pull
 Cross
caster is the side-to-side
difference in caster measurements
 More
than 1/2º difference side-to
side may cause the vehicle to pull
to the wheel with the least positive
caster.
Courtesy of Hunter Engineering Company
Cross Caster
Cross Caster = Left caster minus right caster
2º caster
1º caster
Vehicle may pull to side of least positive caster
Courtesy of Hunter Engineering Company
Caster Specification
 Preferred
Spec
Front 3.80º
Rear n/a
 Tolerance
Front 1º
 Cross caster
.85º
Courtesy of Hunter Engineering Company
Review
 Purpose
of Alignment Angles
 Camber





Definitions
Measurement method
Specification
Tire wear factor
Pull factor
Courtesy of Hunter Engineering Company
Review
 Caster





Definitions
Measurement method
Specification
Tire wear factor
Pull factor
Courtesy of Hunter Engineering Company
Front Toe Angles
 Incorrect
cause:
front toe angles may
– outside shoulder wear
– inside shoulder wear
– wandering
– darting
 Total
toe changes as the speed of
the vehicle increases
Courtesy of Hunter Engineering Company
Total Toe

The difference in the
distance measured
between lines drawn
through the center
of tires on the same
axle.

Measurements are
taken at the front
and rear of the tires.
Courtesy of Hunter Engineering Company
Zero Total Toe
 Equal
distance
when
measured
across the
front and the
rear of tires
on the same
axle.
Courtesy of Hunter Engineering Company
80”
80”
Toe-In
 Measured
distance is
shorter
between the
front of the
tires.
79”
 front = 79 in.
 rear = 80 in.
Total toe-in = 1 in.
80”
Courtesy of Hunter Engineering Company
Excessive Toe-In Tire Wear
Outside
shoulder
wear
Center
of car
Courtesy of Hunter Engineering Company
Toe-Out
 Measured
distance is
shorter
between the
front of the
tires.
 front = 80 in.
 rear = 79 in.
Total toe-out = 1 in.
Courtesy of Hunter Engineering Company
80”
79”
Excessive Toe-Out Tire Wear
Inside
shoulder
wear
Center
of car
Courtesy of Hunter Engineering Company
Total Toe Angle
 The
Total toe
may also be
displayed as an
angle and
expressed in
degrees.
Courtesy of Hunter Engineering Company
Total
toe angle
Total Toe Specification
 Negative
number
indicates
Toe-Out
 Positive
number
indicates
Toe-In
Courtesy of Hunter Engineering Company
Individual Toe
 Front
individual toe is responsible for
steering wheel position
Courtesy of Hunter Engineering Company
Front Individual Toe
formed
by the
intersection of
the geometric
centerline and
a line drawn
through the
center of the
wheel
Courtesy of Hunter Engineering Company
toe
angle
Centerline
 Angle
Left Front
Individual
toe angle
Rear Individual Toe
Rear individual toe
is responsible for:
 tire
wear
 thrust angle
 vehicle tracking
Courtesy of Hunter Engineering Company
Rear Tire Wear Patterns
 Toe-In
– Outside shoulder
 Toe-Out
– Inside shoulder
 Diagonal
Wipe
– a condition that
may result on rear
tires with
excessive toe
Diagonal Wipe
Courtesy of Hunter Engineering Company
Geometric Centerline
A
line drawn between the midpoint
of both the front and rear axles.
Courtesy of Hunter Engineering Company
Thrust Line
 The
bisector of rear total toe. Also
described as the direction the rear
wheels are pushing the vehicle.
Courtesy of Hunter Engineering Company
 Thrust
Angle - formed by the
intersection of the geometric
centerline and the thrustline ( a
line bisecting rear total toe )
Thrustline
Thrust angle
Geometric Centerline
Courtesy of Hunter Engineering Company
Positive & Negative
Thrust Angle
Positive
Thrust
Angle is to
the Right
Negative
Thrust
Angle is to
the Left
+
Courtesy of Hunter Engineering Company
Dog Tracking
A
visible dog track condition will be
present, if the thrust angle is
excessive.
Courtesy of Hunter Engineering Company
Review
 Front
total toe is responsible for
tire wear factors:
– excessive toe-in =
outside shoulder wear
 darting

– excessive toe-out =
inside shoulder wear
 wandering

 Front
individual toe is responsible
for steering wheel position
Courtesy of Hunter Engineering Company
 Thrustline:
the direction the rear
wheels are pointing the vehicle
 bisector of the total toe angle
 Thrust
Angle: the angle formed by
the intersection of the geometric
centerline and the thrustline
 Rear tire wear patterns:
 outside or inside shoulder wear
 diagonal wipe if the toe angle is
extreme
Courtesy of Hunter Engineering Company
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