FSB 728-003

Mack Trucks
Greensboro, NC USA
Field Service Bulletin
Trucks
Date
Group
No.
Release
Page
4.2017
728
003
01
1(9)
Height Control Arm Position, Adjustment
CHU, CXU
FSB 728-003, Height Control Arm Position,
Adjustment
(April 2017)
Some MACK CXU612/CHU612 trucks built from October 4, 2010 to February 6, 2017 with
single rear axle Hendrickson air suspension (RAD-A2H) and short tapered frame rail
(RFL830, RF-TAP28/RF-TA28T) could have the level arm rise above the frame rail when
suspension is lowered completely. To eliminate this problem the arm should be adjusted
(rotated 180°) forward and the leveling rod should be moved to the front of the air spring
support crossmember and reinstalled with bracket (part number 20839697) and existing
hardware.
Note: This bulletin does not apply to MACK Trucks Australia.
PV729-FSB728-003_M
USA138758284
Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
W7121287
Required Parts (Height Control Arm Position, Adjustment)
Item
Description
Part Number
Qty
1
Height Control Rod Bracket
20839697
1
Page
2(9)
Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
Decommissioning the Truck for Repair
You must read and understand the precautions and guidelines in Service Information,
group 70, "General Safety Practices, Frame, Springs, Shocks & Wheels" before
performing this procedure. If you are not properly trained and certified in this procedure,
ask your supervisor for training before you perform it.
NOTE: Information is subject to change without notice. Illustrations are used for reference
only and can differ slightly from the actual vehicle being serviced. However, key
components addressed in this information are represented as accurately as possible.
1 Park the vehicle on a flat and level surface.
2 Apply the parking brake.
3 Place the transmission in neutral or park.
4 Install the wheel chocks.
W7086748
5 Disconnect the cable from the battery’s negative terminal.
W3086747
Page
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
Height Control Arm Position Adjustment Procedure
1 Using the dash mounted rear suspension air dump switch, release the air from the air
springs.
2 Remove the fastener securing the leveling rod to the air spring support crossmember
bracket.
Note: Store the fastener for reuse.
W7121288
3 Position the level control rod away from the control rod bracket as shown.
W7121289
Page
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
4 Remove the fasteners securing the control rod bracket to the air spring support
crossmember bracket.
Note: Clean the fasteners of any debris and store them for reuse.
W7121290
5 remove the bracket from the air spring support crossmember.
W7121291
Page
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
6 Install bracket (part number 20839697) on the air spring support crossmember bracket
using the previously stored fasteners.
7 Tighten the fasteners to 24 ± 4 Nm (18 ± 3 ft-lb).
W7121292
8 With the leveling rod still attached, rotate the control arm 180 degrees. See the figure
below for reference.
W7121294
Page
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
9 Using the stored fastener, connect the level control rod to the air spring support
crossmember bracket as shown in the figure below.
Note: Ensure the level control rod is installed in the middle hole of the air spring support
crossmember bracket.
10 Tighten the fastener securing the level control rod to 2.8 Nm (25.0 in-lb).
W7121295
Page
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
Commissioning the Truck for Operation
1 Connect the battery cable to the negative (ground) terminal.
W3086758
2 Start the truck and build the air system up to normal operating pressure.
3 Remove the wheel chocks.
W7086759
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Mack Trucks
Field Service Bulletin
Date
4.2017
Group
No.
Release
728
003
01
Reimbursement
This repair may be eligible for reimbursement if a
product failure was experienced within time and
mileage limits of the applicable Warranty coverage.
Reimbursement is obtained via the normal claim
handling process.
UCHP
Reimbursement
Claim Type (used only when uploading from the Dealer
Bus. Sys.)
01
Labor Code
Primary Labor Code (Height Control Arm Position,
Adjustment)
7281-05-09-01
0.3 hrs.
Causal Part
22586327
MACK Trucks North America reserves the right to make any changes in design or to make
additions to or upon its products without incurring any obligations to install the same on
vehicles previously built.
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