GROUP
SUSPENSION

Technical Service Bulletin

DATE
FEBRUARY 2020

SUBJECT

NUMBER
20-SS-001H
MODEL(S)
ALL

WHEEL ALIGNMENT REQUIREMENTS
AND BEST PRACTICES

THIS TSB SUPERSEDES 16-SS-001 TO UPDATE THE VEHICLE ALIGNMENT DATA SHEET AND
THE VEHICLE ALIGNMENT DIAGNOSTIC FLOWCHART.
Description: This bulletin describes the requirements for all wheel alignment and/or vehicle tracking
claims and best practices when diagnosing and conducting alignment-related repairs for all models
and model years.

Applicable Vehicles: All

NOTES
Aligner Calibration/Maintenance Schedule - All dealer alignment racks must be
calibrated by a representative every six months. This frequency allows the representative to
update vehicle specifications, and inspect and maintain equipment.
• The Vehicle Alignment Data Sheet located at the end this TSB MUST be stored with the RO for
ALL alignment and/or vehicle tracking claims. (All models and model years)
• Additionally, if an alignment is performed, a before and after measurements printout MUST be
stored with the RO for ALL alignment and/or vehicle tracking claims. (All models and model
years)
o The VIN MUST be included on the alignment printout.
• Always refer to the applicable vehicle shop manual for alignment specifications.
• For all alignment-related conditions, Dealers and Sublet Vendors must adhere to the Vehicle
Alignment Diagnostic Flowchart located on Page 2, and at the end of this TSB.
• Test drives should be performed without passengers or excessive cargo in the vehicle.
• The Absolute Steering Position (ASP) calibration must be performed using GDS on vehicles
equipped with Electric Power Steering (EPS/MDPS) after an alignment has been completed.
• To perform a proper vehicle drift/pull diagnosis, use a Hunter GSP 9700 equipped with
StraightTrak.
•

Circulate To: General Manager, Service Manager, Parts Manager, Warranty Manager, Service
Advisors, Technicians, Body Shop Manager, Fleet Repair

SUBJECT:

WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES

Warranty Information:
Model
Op. Code

Operation

Op. Time

Causal Part

Nature
Code

Cause
Code

Alignment
ALIGN1.1
D44
ZZ5
Diagnosis/Repair
00000
The Vehicle Alignment Data Sheet must be completely filled and attached to the RO for any vehicle
drift/pull and/or alignment warranty claims.
ALL

52903A00

If an alignment is performed, the machine printout displaying the before and after measurements
must also be attached to the RO, and the measurements must be included in the technician’s
comment section of the warranty claim.
Vehicle Alignment Diagnostic Flowchart

NOTES
• When a vehicle is received with an alignment/drift/pull/steering wheel off-center condition, the
service writer should document the customer comments on the Vehicle Alignment Data Sheet.
• Refer to the last 2 pages of this TSB for the detailed flowchart and data sheet.
• Many issues can contribute to vehicle drift or pull, including tire pressure, tire uniformity, wheel
alignment, brake drag, road crown, cross winds, spring sag resulting in ride height differences,
cargo load/weight distribution, and more.
• Consider all potential effects when diagnosing and confirming a vehicle drift or pull condition.

TSB #: 20-SS-001H

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SUBJECT:

WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES
Road Test Procedure

NOTE
Perform road testing without passengers (driver only) and excessive weight.
1. Locate an acceptable vehicle testing road which meets the following criteria:

Recommendations

Cautions

- Road is straight for at least 250m (820 ft).
- Road grade: 1.2 to 1.7 degrees maximum. The flatter the
better.
- Lane width: 3 to 3.5 meters (10-11.5 feet).
- Conduct the test on a smooth, even road without bumps or
grooves.
- Do not test on a road with excessive grade/crown.
- Conduct the test on an uncrowded road.
- Do not test when strong winds are present.

2. Before test driving, verify that all tires are OEM, correctly installed (directional tires, correct
placement for staggered sizes, etc), and set to the correct inflation pressure.

NOTE
For best accuracy, use the GDS to measure tire pressures under TPMS system:
Current Data.
3. If equipped, turn OFF all driver’s assist systems.
4. Drive through the vehicle testing road at 40 MPH. Center the steering wheel, then slightly turn
the wheel ~3 degrees to the left and ~3 degrees to the right to identify the steering center.
With a light touch, center the steering wheel with the vehicle tracking as straight as possible.

NOTE
If the vehicle drives straight but the steering
wheel is off-center, perform an alignment to
correct the condition.

TSB #: 20-SS-001H

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WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES

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5. Note which direction the vehicle has a tendency to drift towards. If the vehicle tends towards
the left, place the vehicle on the right side of the lane. If the vehicle tends towards the right,
place the vehicle on the left side of lane as shown below.

NOTE
To ensure accuracy, repeat the test with the vehicle travelling in the opposite
direction (on the same road).

6. Take time measurements to determine how long it takes for the vehicle to move from one side
of the lane to the other side (case 1), as shown. Use the conditions in the table below to
confirm drifting or pulling condition.
Condition
The vehicle moves from
one side of the lane to the
other side of the lane
(about 1m or 3.3 feet).

Drift/Pull Criteria
Pass

The movement takes more than 6
seconds at 40 MPH.

Fail

The movement takes 6 seconds or
less at 40 MPH.

TSB #: 20-SS-001H

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WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES
Alignment Angle Definitions

Camber The angle between the vertical axis of
the wheel and the vertical axis of the
vehicle when viewed from the front or
rear.

Caster

•

Positive (green line): The upper
sidewall of the tire is tilted away from
the center of the vehicle.

•

Negative (red line): The upper
sidewall of the tire is tilted towards
the center of the vehicle.

When viewing a vehicle from the side,
the angle of the steering axis is defined
by drawing a line through the upper and
lower ball joints (for a double wishbone
front suspension), or through the strut
tower mount and the lower ball joint (for
a MacPherson strut front suspension).
•

Positive (green line): The line leans
towards the rear of the car.

•

Negative (red line): The line leans
towards the front of the car.

TSB #: 20-SS-001H

+º

0º

-º

-º 0º +º

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WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES

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Toe

The amount the tires point inwards or
outwards when viewing the car from
above.
•

Positive (green line): Toe-in – the
tires point inwards towards the
center of the vehicle.

•

Negative (red line): Toe-out – the
tires point outwards away from the
center of the vehicle.

-º

0º

+º

Factors that Influence Vehicle Drift/Pull
Vehicle drift or pull can be attributed to several factors. Understanding what can affect drift/pull is
necessary to repair a vehicle with a drift or pull condition.
Air pressure – A front tire with low pressure can cause a vehicle to drift or pull towards that tire.
Alignment
• Camber – A vehicle will drift or pull towards the side with more positive front camber. The camber
difference between the front tires should be less than 0.5 degrees.
• Caster – A vehicle will tend to drift or pull towards the side with less positive caster.
• Toe – Front and rear toe alignment will not affect vehicle drift or pull performance. Front and
rear toe alignment can cause conditions including steering wheel being off center, dog-tracking, tire
wear issues, and altered vehicle handling characteristics.
• Steering Axis Inclination (SAI) – When viewed from the front of the vehicle, the angle formed by a
line drawn through the steering pivot axis with a line at true vertical. SAI is designed into the
suspension and aids in straight-line stability. This angle can be measured by an alignment
machine. For Hunter units, SAI is measured during the caster sweep process. When the SAI
difference between left and right sides is more than 1 degree, check for damaged components.
o If SAI is lower on one side of the vehicle, this may indicate a bent lower control arm.
o If SAI is higher on one side of the vehicle, this may indicate damage to the upper strut
mount.

TSB #: 20-SS-001H

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WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES

• Thrust angle – The direction the rear axle is pointing as a result of the rear toe angles. This can
result in an off-center steering wheel. To avoid this condition when performing an alignment, rear
camber and toe should be adjusted before adjusting the front alignment. After the rear camber and
toe are adjusted, center the steering wheel, lock the wheel in place, then adjust the front camber,
caster, and toe (if applicable).
Tires – Tires can have a significant effect on vehicle drift or pull. Arranging tires on a vehicle based
on the StraightTrak results can help improve a vehicle drift or pull condition. Tires contribute to
vehicle drift or pull through ply steer and conicity:
• Ply steer – Ply steer is an inherent characteristic in a tire which creates a lateral force as the tire
rolls. Rotating the tires may aid in cancelling ply steer effects.
Conicity – Tire conicity refers to the shape of the tire, and how cone-shaped the tire is. This can
influence vehicle drift or pull. Conicity can be present in a new tire due to a manufacturing condition,
or in a used tire due to camber wear.
Weight – The amount of weight and where the weight is placed alters a vehicle’s alignment angles,
changing the drift/pull tendency. It is important to consider this when diagnosing a vehicle drift or pull.
Road Crown – Every vehicle has the tendency to follow road crown towards the low side of the
crown. It is important to road test a vehicle for a drift/pull condition on as flat a road as possible.
Brake Drag – If one side of the vehicle brakes are dragging, the vehicle can have a drift or pull
tendency towards that side. Inspect the brake system to ensure brake drag not a contributing factor
to drift or pull performance.
Cross Winds – Cross winds can push a vehicle towards one side of the road. Conduct road testing
by driving a vehicle in opposite directions to verify the effects of cross winds.

TSB #: 20-SS-001H

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WHEEL ALIGNMENT REQUIREMENTS AND BEST PRACTICES
Proper Alignment Rack Usage and Maintenance

NOTE
•

Aligner Calibration/Maintenance Schedule - All dealer alignment racks must be
calibrated by a representative every six months. This frequency allows the
representative to update vehicle specifications, and inspect and maintain equipment.

•

These guidelines apply to Hunter Engineering alignment racks and wheel balancers that
feature StraightTrak.

•

The following items must be followed to ensure accurate alignment readings.

Rolling Compensation - The rolling compensation procedure is critical for ensuring an accurate
alignment. When performing rolling compensation, perform the following actions:
1. Set tire pressure to factory specification.
2. Verify that the vehicle is not excessively loaded. Remove any heavy items.
3. Ensure the lift is level so that the suspension and steering are in a neutral position.
4. Set the target levels before rolling compensation. After completing the compensation, do not
re-level the targets.
Roll the vehicle by turning the left rear tire. This
action will not disturb the suspension and steering
systems.

NOTE
Do not roll the vehicle by pushing or
pulling on body surfaces, bumpers, etc.

If equipped, ensure the pins are in the slip plates,
and the turnplate bridge is oriented so that the
bridge is level/flush with the rolling surface to
minimize the vehicle’s suspension movement.

TSB #: 20-SS-001H

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