Service Bulletin

Bulletin No.:

17-NA-170

Date:

May, 2023

INFORMATION
Subject:

Information on Hunter Road Force Balancer

Brand:

Model:

All

GM
Passenger
Cars and
Trucks
(includes
Medium
Duty)

Model Year:

VIN:

from

to

from

to

2000

2024

—

—

Involved Region or Country

Transmission:

—

—

North America, Argentina, Brazil, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru,
Uruguay, Venezuela, Europe, Middle East, Iraq, Israel, Palestine, Japan, Cadillac Korea
(South Korea), GM Korea Company, China, Taiwan, Thailand, Singapore, Philippines,
Australia/New Zealand, Egypt

Information
Effective February 2017 (May 2017 for Canada), a
Generation 3, 4 or 5 Hunter Road Force Balancer is
designated as Essential Dealer Equipment. The Hunter
road Force Balancer is required to be utilized for all
repairs requiring balance and Road Force
measurement (see list of Labor Operations below). No
other wheel balancer will be considered an acceptable
substitute in GM Dealers. The Hunter Road Force
Balancer allows technicians to perform a static balance
and to check Road Force during a single measurement.
With the use of the Hunter Road Force balancer,
technicians can be sure that the tire/wheel assembly
meets or exceeds GM specifications prior to mounting

Copyright 2023 General Motors LLC. All Rights Reserved.

Engine:

the assembly back onto the vehicle. This ensures that
problem(s) can be corrected early in the process. This
prevents repeat repairs and customer dissatisfaction in
ride quality.

Hunter Generation 3, 4 and 5 Balancers
Currently, the Hunter Road Force Balancer Generation
5 is the latest version available. Any dealer having a
Generation 3, 4 or 5 balancer meets the GM
requirements. Generation 3 only has the ability to
measure up 22" assemblies. Generation 1 and 2
balancers are not capable of properly measuring and
correcting all GM assemblies.

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May, 2023

Bulletin No.: 17-NA-170

GSP9722
(Generation 3)

180 Match Mount process available
Only has the ability to Measure and Correct up to 22”
assemblies
Sizes 23" and higher, Generation 4 or Generation 5 will be
required

Road Force Touch
(Generation 4)

Introduces Touch Screen
180 Match Mount process available
Handles assemblies up to 175 lbs, 40 in tire/30 in rim

Road Force Elite Balancer
(Generation 5)

Touch Screen
180 Match Mount process available
Handles assemblies up to 175 lbs, 40 in tire/30 in rim
Integrated Power Wheel lift – prevents damage to mounting
shaft
SmartScan laser measuring system - Eliminates
measurement arms
Built-in HD video tutorials
Weight placement laser and work light
Color Printer with storage
BulllsEye dual-taper 10 collet center kit

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Why is the Hunter Road Force Balancer
Needed?
Today’s cars and trucks have many advanced braking
and stability systems. All of these help with better
braking and control of the vehicle. Additionally, stricter
fuel economy standards are driving many innovations
to meet these new standards including lower rolling
resistance tires with a decreased contact patch. To
meet these requirements, suspension systems and
tires are getting stiffer and many of todays tire/wheel
assemblies can weigh as much as 80 lbs (36 kg). We
are also seeing a customer trend for larger wheels in
sizes of 20” and 22.” Because of this, having properly
balanced wheel/tire assemblies and low Road Force
tires readings are essential to ride quality. Only by
using the Hunter Road Force Balancer will the
technician know that the tire/wheel assemblies meet
the GM specifications prior to mounting them back on
the vehicle.

What is Road Force?
Previously, tire/wheel assemblies were measured for
“static balance.” This allowed for weights to be placed
on the inside and outside of the wheel flange/rim
surface. While this is the first step, todays vehicles also
need the Road Force checked. Road Force is a
measurement of both sidewall stiffness and how much
the assembly is “Egg Shaped.”

What Produces Road Force?
To understand the effects of radial force variation,
imagine the tire as a collection of springs between the
rim and the tire tread. If the “springs” are not of uniform
stiffness, a varied force is exerted on the axle as the tire
rotates and flexes. This creates a vibration in the
vehicle. (Hunter Engineering)

Bulletin No.: 17-NA-170

May, 2023

Vibration Source From Radial Force Variation

Page 3

Hunter has developed the “180-Match Mount” process
(

).
This process allows a more precise measurement and
correction to the Tire/Wheel Assembly by using the
Road Force measurements to determine proper
alignment of the tire to the wheel which produces the
lowest Road Force. See the section below titled “180
Matching with Flangeless Wheels (Hunter machine)” for
more information.

Centering Check
Centering Check is an inspection and verification of the
wheel’s mounting to the balancer. It is used to identify
possible centering errors. These errors can occur with
debris or wheel mating surface damage. Both of these
can affect the measurement process. The Centering
Check procedure identifies these problems prior to
performing the balance and Road Force measurement.
If an error occurs during the procedure, an error popup
will appear with text explaining the error. The Centering
Check must be performed on all assemblies to prevent
inducing errors in the process.
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The Hunter Road Force Balancer has the ability to
measure this variation. By measuring, correcting and
validating the Tire/Wheel Assembly is in spec for both
static and Road Force, the Technician can be assured
that the tire/wheel assembly is correct prior to mounting
it back on the vehicle. Excessive Road Force can also
be produced by incorrect tire mounting or improper
bead seating to the rim. Both of these will provide a low
and/or high spot in that area. This can occur on either
the inside or outside flange. By measuring the Road
Force, the Hunter is able to identify a problem before
the tire/wheel assembly is mounted back on the
vehicle.

Hunter Road Force Balancer for Correcting
Customer Complaints
Many of todays GM vehicles have a new design wheel.
These new wheels have removed the machined flange
that previously would have allowed for the traditional
“bang-on” weights. This was removed for aesthetic
reasons but has also driven the need for changes in
balancers. Modern balancers need to account for this
by allowing wheel weights to be placed on the inside of
the wheel. Additionally, the previous method of
“vectoring” or “Match Mounting” a tire cannot be utilized
since the starting point is to measure the wheel runout
using measurement arms. To address this concern,

Measuring Wheel Runout and Assembly Radial
Force Variation/180 Matching Procedure
(Hunter)
Important: The completed worksheet must be
attached to the hard copy of the repair order.
To access the Vibration Diagnostic Worksheet, Go
to > Global Connect > Service Forms > General
Information > Vibration Diagnostic Worksheet.
• Measure radial force variation and radial runout.
• Record the radial force variation (RFV) on the
worksheet. It may be of benefit to have the lowest
RFV assembly to the front left corner.
• Flangeless wheels are commonly used today and
the runout cannot be measured accurately with
the tire on the wheel. There is no machined
surface on the outside of the wheel like on the
flanged wheel so for an accurate runout
measurement, the wheel should be dismounted
and a reading should be taken on the inner bead
seat area of the wheel or the (Hunter) 180
Matching procedure can be used (see below). The
runout spec is the same as a flanged wheel.

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May, 2023

Bulletin No.: 17-NA-170

4540628

Legend
(1)

Flangeless Rim

(2)

Flanged Rim

180 Matching with Flangeless Wheels (Hunter
machine)
On flangeless wheels, the 180 Matching procedure can
be used when using a Hunter 3rd, 4th or 5th generation
machine. This can be used with the tire still on the
wheel.
Hunter 180 Matching Procedure (this information can
also be found in the Hunter manual for your machine):

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Bulletin No.: 17-NA-170
•

May, 2023

Page 5

180 Matching will minimize Road Force® in the
tire and wheel assembly. It requires a tire changer,
as the tire will be repositioned about the wheel
during the procedure. The 180 Matching
procedure can be launched by touching the Road
Force® button, then Procedure and then 180
Matching buttons.

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There is a progress bar at the top of the screen to show
how far along the procedure has progressed.
1. Mount the assembly on the balancer.
2. Set the tire pressure to the vehicle manufacturer’s
specification.
3. Lower the hood to start the Road Force®
measurement.
4. Position the valve stem at 12:00 and touch “Enter
Valve Stem.”
5. Mark the tire with a piece of chalk or a marker with
a “V” opposite the valve stem as indicated. Touch
“OK” or tap the foot pedal when completed.
6. Use a tire changer and rotate the rim 180 degrees