Hummer H2. Manual - part 2131

Tools Required 

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J 21552 Rack Piston Arbor. See Special Tools and Equipment .  

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J 8947 Rack Piston Teflon Ring Compressor  

Disassembly Procedure 

Fig. 66: Turning Stub Shaft Counterclockwise Until Rack Piston Begins To Come Out Of Steering 
Gear Housing 
Courtesy of GENERAL MOTORS CORP. 

1. Remove the pitman shaft seals and bearing. Refer to Pitman Shaft Seals and Bearing Replacement - 

Off Vehicle (700 Gear) .  

2. Remove the housing end plug. Refer to Steering Gear Housing End Plug Replacement - Off Vehicle .  

3. Turn the stub shaft counterclockwise until the rack piston (2) begins to come out of the steering gear 

housing (3).  

4. Remove the rack piston plug (1).  

5. Insert J 21552 into the bore of the rack piston (2). See Special Tools and Equipment .  

IMPORTANT: Do not remove the needle bearing when removing the pitman shaft arm 

and its components.

 

2004 Hummer H2 

2004 STEERING Power Steering System - Hummer H2

  

6. Hold J 21552 tightly against the worm shaft while turning the stub shaft counterclockwise. Turning the 

stub shaft forces the rack piston (2) onto J 21552 . The rack piston balls remain in place. See Special 
Tools and Equipment . 

Fig. 67: Removing Steering Gear Housing Components 
Courtesy of GENERAL MOTORS CORP. 

7. Remove the following items as an assembly from the steering gear housing (9): 

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The rack piston (4)  

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The rack piston screws (8), clamp (7), ball guide (6) and balls (5)  

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J 21552 . See Special Tools and Equipment .  

8. Remove the spool valve assembly. Refer to Steering Gear Valve Replacement - Off Vehicle (700 

Gear) .  

9. Remove the worm shaft (14).  

10. Remove the thrust bearing (12) and the flat races (11, 13). 

IMPORTANT: When removing J 21552 , watch for falling piston balls (5) from inside the 

rack piston (4). See Special Tools and Equipment .

 

2004 Hummer H2 

2004 STEERING Power Steering System - Hummer H2

  

11. Remove J 21552 from the rack piston (4). See Special Tools and Equipment .  

12. Remove the rack piston balls (5).  

13. Remove the following items from the rack piston (4): 

1. The screws (8)  

2. The clamp (7)  

3. The ball guide (6)  

4. The remaining rack piston balls (5) in the ball guide (6)  

14. Remove the teflon ring (2).  

15. Remove the O-ring seal (3).  

16. Clean all of the disassembled parts.  

17. Inspect all of the disassembled parts for wear.  

18. Replace the parts if necessary.  

Assembly Procedure 

Fig. 68: Installing O-Ring Seal & Teflon Ring 
Courtesy of GENERAL MOTORS CORP. 

1. Install the O-ring seal (3) and the teflon ring (2). 

 

2004 Hummer H2 

2004 STEERING Power Steering System - Hummer H2

  

2. Lubricate both parts with power steering fluid.  

3. Install the worm shaft (14) to the rack piston (4) outside of the steering gear housing (9). 

Fully seat the worm shaft to the rack piston. 

Fig. 69: Aligning Worm Shaft Spiral Groove With Rack Piston Ball Return Guide Hole 
Courtesy of GENERAL MOTORS CORP. 

4. Align the worm shaft spiral groove with the rack piston ball return guide hole (1). 

5. Lubricate the rack piston balls with power steering fluid.  

6. Insert the rack piston balls through the ball return guide hole (1) while turning worm shaft (2) 

counterclockwise in order to install the rack piston balls into the rack piston. Install the black and the 
silver rack piston balls alternately into the rack piston and the ball guide to maintain the rack piston to the 
worm shaft preload. 

CAUTION: In order to avoid injury and/or component damage, install all of the 

rack piston balls into the rack piston. Install the rack piston balls in 
the correct order. If you do not correctly install all of the rack piston 
balls, the steering gear may not operate or may wear out quickly.

 

2004 Hummer H2 

2004 STEERING Power Steering System - Hummer H2