GM Astro/Safari 1985-1996 Repair Guide

Power Steering Gear

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The recirculating ball type power steering gear used on these vehicles is basically the same as the manual steering gear, except that it uses a hydraulic assist on the rack piston.

The power steering gear control valve directs the power steering fluid to either side of the rack piston, which rides up and down the worm shaft. The steering rack converts the hydraulic pressure into mechanical force. Should the vehicle loose the hydraulic pressure, it can still be controlled mechanically.

ADJUSTMENTS



Steering gear adjustments are made only as corrections and NOT as periodic adjustments. Before adjusting the gear, check the remainder of the steering linkage and front suspension for wear or damage and repair/replace components, as necessary. Adjustment takes place in 2 major steps. First the worm bearing preload adjustment is made using the adjuster plug, then the overcenter preload is adjusted using the adjuster screw/bolt and jam nut.

To perform adjustments to the power steering gear, it is recommended to remove the power steering gear from the vehicle and place it in a vise. Before adjustments are performed to the system, be sure to check problems relating to hydraulic pressures and performance.

Worm Bearing Preload

See Figures 1, 2, 3 and 4



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Fig. Fig. 1: Remove the adjuster locknut from the gear by driving it counterclockwise



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Fig. Fig. 2: Matchmark the housing with the adjuster plug hole



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Fig. Fig. 3: Measure back (counterclockwise) and scribe a second mark



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Fig. Fig. 4: Use the spanner wrench to align the adjuster plug with the second mark

The following procedure requires the use of the GM Adjustable Spanner Wrench tool No. J-7624 or equivalent.

  1. Remove the steering gear from the vehicle and position it in a vise. For details, please refer to the procedure found earlier in this section.
  2.  
  3. Using a hammer and a brass punch, drive the adjuster plug locknut counterclockwise and remove it from the end of the steering gear.
  4.  
  5. Use an adjustable spanner wrench such as J-7624 or equivalent, to turn the adjuster plug inward, until it firmly bottoms in the housing with a torque of 20 ft. lbs. (27 Nm).
  6.  
  7. Use a scribing tool to place a matchmark (on the housing) next to the one of the spanner wrench holes in the adjuster plug.
  8.  
  9. Using a ruler, measure 1 / 2 in. (13mm) counterclockwise from the scribed mark (on the housing) and place another mark.
  10.  
  11. Use the spanner to turn the adjuster plug (counterclockwise) until the hole in the adjuster plug aligns with the 2nd scribed mark.
  12.  
  13. While holding the adjuster plug in alignment, install and tighten the adjuster plug locknut.
  14.  
  15. Perform the overcenter preload adjustment.
  16.  

Overcenter Preload

See Figures 5, 6 and 7



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Fig. Fig. 5: Align the stub shaft with the side cover



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Fig. Fig. 6: Align the pitman arm shaft master spline



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Fig. Fig. 7: Use an inch lbs. torque wrench to measure overcenter rotation torque

  1. Adjust the worm bearing preload. For details, please refer to the procedure earlier in this section.
  2.  
  3. Rotate the stub shaft from stop-to-stop and count the number of turns necessary.
  4.  
  5. Starting from 1 stop, turn the stub shaft back 1 / 2 the number of turns (to the center of the gear).
  6.  

With the stub gear centered, the flat on top of the shaft should face upward and be parallel with the side cover; the master spline on the pitman shaft should be in line with the adjuster screw.

  1. Loosen the pitman shaft adjuster screw locknut, then turn the adjuster screw counterclockwise until it is fully extended. Turn the screw clockwise 1 full turn.
  2.  
  3. Place a 0-50 inch lbs. (0-6 Nm) torque wrench vertically on the stub shaft, then rotate it 45° (to each side) and record the highest drag measured near or on the center.
  4.  
  5. Turn the adjuster screw inward until the torque on the stub shaft is 6-10 inch lbs. (0.7-1.2 Nm) greater than the initial reading.
  6.  
  7. Tighten the adjuster screw jam nut while holding the adjuster screw from turning. Double check for the proper measurement to assure the screw was not turned while tightening the nut.
  8.  
  9. Install the power steering gear into the vehicle.
  10.  

REMOVAL & INSTALLATION



See Figure 8



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Fig. Fig. 8: Exploded view of the power steering gear mounting

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Raise and support the front of the vehicle safely using jackstands.
  4.  
  5. Position a fluid catch pan under the power steering gear.
  6.  
  7. At the power steering gear, disconnect and plug the pressure hoses; any excess fluid will be caught by the catch pan.
  8.  

Be sure to cap or plug the hoses and the openings of the power steering pump to keep dirt out of the system.

  1. Remove the intermediate shaft-to-steering gear bolt. Matchmark the intermediate shaft-to-power steering gear and separate the shaft from the gear.
  2.  
  3. Remove the pitman arm-to-pitman shaft nut and washer, then matchmark the relationship of the arm to the shaft (this will permit proper alignment during assembly).
  4.  
  5. Separate the pitman arm from the pitman shaft using J-29107, or an equivalent pitman arm removal tool.
  6.  

When separating the pitman arm from the shaft, DO NOT use a hammer or apply heat to the arm.

  1. Remove the power steering gear-to-frame bolts and washers, then carefully lower and remove the steering gear from the vehicle.
  2.  

To install:
  1. Install the steering gear, then tighten the gear-to-frame bolts to 55 ft. lbs. (75 Nm) for 1985-93 vehicles and 1994-96 2 wheel drive vehicles, or tighten the bolts to 100 ft. lbs. (135 Nm) for 1994-96 AWD vehicles.
  2.  
  3. Remove the plugs, then connect the pressure hoses to the power steering gear.
  4.  
  5. Connect the intermediate shaft-to-power steering gear bolt and tighten to 30 ft. lbs. (41 Nm)
  6.  
  7. Align and install the pitman arm-to-pitman shaft, then install the nut and washer and tighten to 185 ft. lbs. (250 Nm).
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Refill the power steering reservoir and bleed the power steering system.
  12.  
  13. Remove the jackstands and carefully lower the vehicle.
  14.  
  15. Road test the vehicle, then check and top-off the power steering fluid.
  16.  

 
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