NHTSA ID Number: 10125183
Manufacturer Communication Number: FSB431-010
TSB/Document Date: 2017-12-14
Summary
This procedure is to repair mDrive transmissions in the field that exhibit a grinding noise when the transmission range shifts (for example: between 6th and 7th gear) built between 01/01/2013 and 08/18/2014.
Mack Trucks
Greensboro, NC USA
Field Service Bulletin
Trucks
This Field Service Bulletin replaces bulletin “Range Synchronizer, Repair“,
(USA70647) PV729–FSB431-010_M, dated 04/2015.
Date
Group
No.
Release
Page
10.2017
431
010
03
1(36)
Range Synchronizer, Repair
CHU, CXU
FSB 431-010, Range Synchronizer, Repair
(October 2017)
This procedure is to repair mDrive transmissions in the field that exhibit a grinding noise
when the transmission range shifts (for example: between 6th and 7th gear) built between
01/01/2013 and 08/18/2014.
Required Parts
I-Shift Range Synchronizer Repair Kit, Part Number 85020354
TECU main software equal to or greater than 23084204
Optional Parts
Note: The assembly should be disassembled and inspected before ordering optional parts.
Range Shift Fork, Part Number 21510395
Set Screws, Part Number 1652847
Required Tools
Special tools: 9809726, 9990027, 9992619, 9992671, 9992884, 9996315, 9996876,
9996889, 9996917, 9998051, 9998542, 85108826, 88800015
Premium Tech Tool version 2.06.20 or higher
Vocom Diagnostic Connector 88890304 or 88890253
Communication Interface 88890300
Note: Using other interfaces may affect programming speed.
Note: Check Premium Tech Tool version by clicking on Help tab and then click on “About
Tech Tool”.
PV729-FSB431-010_M
USA139709329
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
Failed Parts
W4096430
The synchronizer ring is missing the high range friction material and the low range side is
wearing away.
Procedure
You must read and understand the precautions and guidelines in Service Information,
Function Group 40, "General Safety Practices, Transmission" before performing this
procedure. If you are not properly trained and certified in this procedure, ask your
supervisor for training before you perform it.
DANGER
Do not attempt to repair or service this vehicle without having sufficient training, the
correct service literature and the proper tools. Failure to follow this could make the vehicle
unsafe and lead to serious personal injury or death.
DANGER
Before beginning any work on any part of the air system, be certain that the air pressure
has been released. Failure to do so may cause a component to violently separate, which
can result in serious personal injury.
Page
2(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
Note: Special tools: 9809726, 9990027, 9992619, 9992671, 9992884, 9996315, 9996876,
9996889, 9996917, 9998051, 9998542, 85108826, 88800015
1 Use Premium Tech Tool (PTT) to perform operation 4000-08-03-11 “Gear activation,
control housing (for removal/replacement)”. Follow the instructions in PTT.
Note: If Tech Tool is unable to activate the necessary gears for control housing removal,
follow the manual activation steps outlined in this procedure after transmission removal.
2 Secure the vehicle for service by parking it on a flat level surface, applying the parking
brake, chocking the rear wheel, and placing the transmission in neutral.
3 Disconnect all cables from the negative (ground) battery terminals to prevent personal
injury from electrical shock and prevent damage to electrical components.
4 Drain the air system.
5 Raise the vehicle and support with jack stands.
Page
3(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
6 Drain the transmission oil into a suitable container.
WARNING
Hot transmission oil can cause burns. DO NOT allow hot transmission oil to contact the
skin. When changing transmission oil, wear protective gloves.
CAUTION
Always dispose of lubricants (engine oil, coolant, transmission oil, etc.) and filters
according to Federal or local regulations. Dumping used oil or coolant on the ground or
in waterways can contaminate our drinking water and kill wildlife.
W4002889
T4022639
Page
4(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
7 Remove the transmission. Refer to Function Group 431.
8 Remove the control housing mounting bolts.
W4002951
9 Remove the six TECU mounting bolts.
Note: It is only necessary to perform this step if manually performing the “Gear activation,
control housing (for removal/replacement)”. If PTT activated the necessary gears,
proceed to step 13.
W4002952
Page
5(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
10 Manually perform the “Gear activation, control housing (for removal/replacement)” as
outlined in the next three steps.
Note: The next three steps are performed only if Tech Tool could not activate the
necessary gears for control housing removal.
11
CAUTION
Electrical components, including the wiring harness inside the transmission control
housing, are delicate. Handle with extreme care. Failure to do so may result in damage
to components.
Gently lift the top edge of the upper cover and angle it down carefully against the clutch
housing. Carefully disconnect the electrical connection and remove the top cover.
Note: Do not apply tension or weight to the wiring harness or connector.
W4002953
Page
6(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
12 Using compressed air, apply air pressure to the appropriate bore holes to place the
transmission gears in the proper position for control housing removal.
Note: It is necessary to rotate the input shaft while engaging the splitter section to mesh
the gears.
Note: It is necessary to rotate the output shaft while engaging the range section to mesh
the gears.
Note: It is necessary to rotate the output or input shaft while engaging reverse to mesh
the gears.
Note: For over drive transmissions, the transmission must be positioned as
follows:
* Low Split
* High Range
* 2nd/3rd — Neutral Position
* 1st/Reverse — Reverse Position
W4002895
Over Drive Transmission
1 – High Range
2 – 3rd Gear
3 – Low Range
4 – 2nd Gear
5 – 1st Gear
6 – High Split
7 – Reverse Gear
8 – Low Split
Page
7(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
Note: For direct drive transmissions, the transmission must be positioned as
follows:
* High Split
* High Range
* 2nd/3rd — Neutral Position
* 1st/Reverse — Reverse Position
W4002895
Direct Drive Transmission
1 – High Range
2 – 3rd Gear
3 – Low Range
4 – 2nd Gear
5 – 1st Gear
6 – Low Split
7 – Reverse Gear
8 – High Split
Page
8(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
Note: If 2nd or 3rd gear is engaged, it will be necessary to position that gear set to neutral
before attempting to engage reverse.
Note: To engage neutral for the 2nd/3rd gear set, it will be necessary to gently apply air to
the bore holes. If too much air is applied, it will engage one of the two gears. To aid
positioning, do not rotate the shaft when attempting to position this gear set.
T4021451
Page
9(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
13
CAUTION
Gentle consistent pressure should be used to lift the control housing from the
transmission. Applying excessive force is not necessary or needed, and may result in
damage to components.
CAUTION
Always install the alignment pins before removing the control housing to prevent
damage to the transmission main shaft speed tone ring and the shift control.
Note: Use tool 9996876.
Install the alignment pins through the control housing into the transmission. Using a pry
bar, gently separate the control housing from the locating pins on the transmission, then
remove the control housing.
Note: If the control housing does not separate from the transmission while applying gentle
pressure upward, it may be necessary to refer back to Step 11 or Step 12 before
attempting control housing removal again.
Note: Exercise care during removal to keep from damaging the tooth wheel in the
transmission.
W4002955
Page
10(36)
Mack Trucks
Field Service Bulletin
Date
10.2017
Group
No.
Release
431
010
03
14 Remove the plug, spring and plunger for the range function. If necessary use a magnet to
pull out the plunger.
C4052785
15 Remove the range housing mounting fasteners.
16 Use press tool to separate the main housing and range housing.
W4088216
1. 9998051
Page
11(36)
Mack Trucks
Field Service Bulletin
Date
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TSB/Document ID: FSB431-010
Replacement Service Bulletin Number:
MFR Communication Date: 2017-11-01
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: POWER TRAIN
MFR Component System:
MFR Component Subsystem:
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