MACK.

Fleet Improvement $4571 August 2025 Release 01 Fleet Improvement

Drag Link and Pitman Arm Replacement

Service Category Service Department

Section Function Group 642

Technician Skill Level A Market North America
Applicability

Mack

Model Years Models

2016-2021 MR, TE

Introduction
At the request of NM representative, Mack Trucks has authorized repairs on 2016—
2021 model year MR and TE trucks operated by MM. For the affected population, please
follow the instructions below to replace the drag link and pitman arm, and to adjust the steering
stops and pressure reliefs as needed.

Production Change Information
This bulletin applies to vehicles built within the specified production changes below.

Brand Engine Emission Level Starting Build Date | Ending Build Date
Mack MP7 EM-USA14, EM-USA17 16-April-2015 21-October-2020

Warranty Information

This repair may be eligible for reimbursement if a product failure was

experienced with in time and mileage limits of the applicable Warranty coverage.

Reimbursement is obtained via the normal claim handling process.

Claim Type (used only when uploading from the Dealer Bus. Sys.) B

Main Labor Code Description Hours
6438-03-02-01 Link Rod, Replacement 0.7
6437-03-02-01 Pitman Arm, Replacement 2.0
6439-05-02-01 Steering Stop, Adjustment 0.4
1720-16-09-01 Campaign, General (0.1 X 2) 0.2

Causal Part 21129355, 21129340

SCC Authorization Code $4571

Expiration Date August 31, 2026

Parts Information

All parts are on mandatory return to TMAC

Part Numbers Part Names Quantity
21129355 Link Rod 1
21129340 Pitman Arm 1

993909 Hexagon Screw 1
994882 Washer 2
990954 Flange Lock Nut 1
25092079 Split Pin 1
20705040 Hexagon Screw 1
20705836 Lock Nut 1
8148-1790972K Arm Retainer 1

Required Tools & Equipment

N/A
Repair Procedure

PwNrP

Park the vehicle on a level surface.
Apply the parking brake.

Place the gear lever in neutral.
Install the wheel chocks.

5. Raise the cab using the tilt pump.

7. Mark the position of the steering gear shaft connection at the pinch bolt.

8. Remove the bolt and shaft from the steering gear.

9. Remove the drag link pinch bolt.
10. Remove drag link from the pitman arm.

11. Use an approved container and drain the power steering system.
12. Disconnect the power steering lines from the steering gear.

13. Position and attach a hoist to the steering gear.
14. Remove the steering gear mounting hardware.
15. Remove the steering gear from the chassis.

16. Put the steering gear on the work bench.
17. Release the locking tabs on the pitman arm retaining bolt.
18. Remove the bolt.

19. Using a puller, remove the pitman arm from the steering gear.

20. Position the new pitman arm on the steering gear making sure to align the
marks.

21. Install the new pitman arm retaining bolt and torque to spec.

Pitman arm, bolt Torque tighten the nut to 746 Nm
(550 Ib ft) and then tighten the nut
until the notches are aligned with
next bent tab of the washer.

22. Bend the locking tab into place.

23. Using a hoist, install the steering gear on the frame.
24. Install the original steering gear mounting hardware and torque to spec.

Steering gear mounting, bolts : 370 +50 Nm (273 +37 Ibr-ft) |

25. Connect the power steering oil lines to the steering gear.

26. Install the steering shaft onto the steering gear making sure to align the marks
made during removal.
27. Install a new pinch bolt and flange lock nut and torque to spec.

Steering shaft, bolts : 30 +3 Nm (22 +2 Ib¢-ft) |

28. Remove the split pin and nut.

29. Remove the old drag link.
30. Install the new drag link on the steering knuckle and pitman arm.
31. Install new drag link pinch bolt and lock nut, torque to spec.

Pitman arm, lower nut : 275 +20 Nm (203 +15 Ibe-ft) |

32. Torque the drag link to knuckle nut and install new split pin.

Link rod, nut : 340 Nm (251 Ib¢-ft) |

33. Fill the power steering reservoir to the proper level.
34. Connect the negative battery cable and install the cover.
35.

36.

37

38.

39.

Lower the cab, start the engine and turn the steering wheel lock to lock to purge
air from the system.
Verify the correct power steering fluid level.

. Verify the steering Curve angle adjustment following Impact repair document

Identity 142168285 Curve angle, adjustment.

If relief plunger adjustment is required follow the manufactures procedure for
adjustment. RH Sheppard Sheppard Service Bulletins and Manuals - RH Sheppard
and click on the D Series Manual.

Remove wheel chocks.