Hummer H1 Service Manual page 529

8-38 Steering System
Pitman Shaft Overcenter Preload Torque
Adjustment
1. Loosen locknut on pitman shaft adjuster screw.
2. Turn adjuster screw counterclockwise until fully extended.
Then turn screw one full turn clockwise.
3. Rotate stub shaft from stop-to-stop and count number of
turns. Then turn stub shaft back 1/2 number of turns. This
will center rack piston and pitman shaft.
4. Verify that gear is centered. Flat on stub shaft should face
upward and be parallel with side cover. In addition, master
spline on pitman shaft should be parallel with adjuster
screw (Figure 8-70). If gear is not centered, number of
turns counted in step 3 may be incorrect, or pitman shaft
sector teeth are not centered in rack piston. Make
necessary corrections before proceeding.
STUB
SHAFT
FLAT
PITMAN SHAFT
MASTER SPLINE
Figure 8-70: Verifying That Gear Is Centered
4-1-00
__________________________________________________________
SIDE COVER
PRELOAD
ADJUSTER
SCREW
5. Measure wormshaft bearing preload as follows:
• Position suitable size 12 point socket and inch pound
torque wrench J–7754-C on stub shaft (Figure 8-71).
• Slowly rotate torque wrench 45 degrees left and right of
center. Note torque readings just before and on center in
both directions. Correct preload torque is 6 to 15 lb-in
(0.7 to 1.7 N•m).
• If preload torque is within limits, continue with proce-
dure as wormshaft bearing preload is correct.
• If preload torque is not within limits, wormshaft bearing
preload adjustment is incorrect, or wormshaft thrust
bearing races were installed backwards. Correct fault
before proceeding.
CENTER
Figure 8-71: Checking /Adjusting Pitman Shaft
Over-Center Preload
6. Adjust pitman shaft overcenter preload as follows:
• Leave torque wrench in place on stub shaft.
• Note wormshaft bearing preload measured in step 5.
Then add additional 6-10 lb-in (0.7 to 1.1 N•m) to this
figure for required overcenter preload.
• Adjust overcenter preload by turning pitman shaft ad-
juster screw clockwise to increase preload, or counter-
clockwise to decrease preload.
7. Tighten adjuster screw locknut to 36 lb-ft (49 N•m)
torque. Use hex wrench to prevent adjuster screw from
turning while nut is tightened.
8. Verify that overcenter preload is still correct before
installing gear in vehicle.
HEX WRENCH
IN PRELOAD
ADJUSTER
SCREW
®