GM Full-Size Trucks 1970-1979 Repair Guide

Manual Steering Gear

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ADJUSTMENTS



Bearing Preload

See Figures 1, 2 and 3



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Fig. Fig. 1: Pitman arm removal and installation



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Fig. Fig. 2: Steering gear adjustment points



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Fig. Fig. 3: Check the torque required to turn the steering wheel

Correct adjustment of steering gear is very important. While there are but two adjustments to be made, the following procedure must be followed step-by-step in the order given.

  1. Disconnect the battery ground cable.
  2.  
  3. Raise the vehicle.
  4.  
  5. Remove the Pitman arm nut. Mark the relationship of the Pitman arm to the Pitman shaft. Remove the Pitman arm with Tool J-6632 or J-5504 as shown.
  6.  
  7. Loosen the steering gear adjuster plug locknut and back the adjuster plug off 1 / 4 turn.
  8.  
  9. Remove the horn shroud or button cap.
  10.  
  11. Turn the steering wheel gently in one direction until stopped by the gear; then turn back 1 / 2 turn.
  12.  


WARNING
Do not turn the steering wheel hard against the stops when the steering linkage is disconnected from the gear as damage to the ball guides could result.

  1. Measure and record bearing drag by applying a torque wrench with a socket on the steering wheel nut and rotating through a 90 degree arc. Do not use a torque wrench having a maximum torque reading of more than 50 inch lbs. (5.6 Nm).
  2.  
  3. Adjust thrust bearing preload by tightening the adjuster plug until the proper thrust loading preload is obtained. When the proper preload has been obtained, tighten the adjuster plug locknut to specifications and recheck torque. If the gear feels lumpy after adjustment, there is probably damage in the bearings due to severe impact or improper adjustment; the gear must be disassembled and inspected for replacement of damaged parts.
  4.  
  5. Adjust over-center preload as follows:
    1. Turn the steering wheel gently from one stop all the way to the other carefully counting the total number of turns. Turn the wheel back exactly half-way, to center position.
    2.  
    3. Turn the lash adjuster screw clockwise to take out all lash between the ball nut and Pitman shaft sector teeth and then tighten the locknut.
    4.  
    5. Check the torque at the steering wheel, taking the highest reading as the wheel is turned through center position.
    6.  
    7. If necessary, loosen locknut and re-adjust lash adjuster screw to obtain proper torque. Tighten the locknut to specifications and again check torque reading through center of travel. If maximum specification is exceeded, turn lash adjuster screw counterclockwise, then come up on adjustment by turning the adjuster in a clockwise motion.
    8.  

  6.  
  7. Reassemble the Pitman arm to the Pitman shaft, lining up the marks made during disassembly. Torque the Pitman shaft nut to specifications.
  8.  

If a clamp type Pitman arm is used, spread the Pitman arm just enough, with a wedge, to slip the arm onto the Pitman shaft. Do not spread the clamp more than required to slip over Pitman shaft with hand pressure. Do not hammer the Pitman arm onto the Pitman shaft. Be sure to install the hardened steel washer before installing the nut.

  1. Install the horn button cap or shroud and connect the battery ground cable.
  2.  
  3. Lower the vehicle to the floor.
  4.  

High Point Centering
  1. Set front wheels in straight ahead position. This can be checked by driving vehicle a short distance on a flat surface to determine steering wheel position at which vehicle follows a straight path.
  2.  
  3. With front wheels set straight ahead, check position of mark on wormshaft designating steering gear high point. This mark should be at the top side of the shaft at 12 o'clock position and lined up with the mark in the coupling lower clamp.
  4.  
  5. If the gear has been moved off high point when setting wheel in straight ahead position, loosen adjusting sleeve clamps on both left and right hand tie rods. Then turn both sleeves an equal number of turns in the same direction to bring gear back on high point.
  6.  

Turning the sleeves an unequal number of turns or in different directions will disturb the toe-in setting of the wheels.

  1. If the gear has been moved off high point when setting wheels in straight ahead position, loosen adjusting sleeve clamps on the connecting rod. Then turn sleeve to bring gear back on high point.
  2.  
  3. Readjust toe-in as outlined previously.
  4.  
  5. Be sure to properly orient sleeves and clamps when fastening and tightening the clamps to proper specifications.
  6.  

REMOVAL & INSTALLATION



  1. Set the front wheels in straight ahead position by driving vehicle a short distance on a flat surface.
  2.  
  3. Remove the flexible coupling to steering shaft flange bolts.
  4.  
  5. Mark the relationship of the Pitman arm to the Pitman shaft. Remove the Pitman shaft nut or Pitman arm pinch bolt and then remove the Pitman arm from the Pitman shaft using Puller J-6632.
  6.  
  7. Remove the steering gear to frame bolts and remove the gear assembly.
  8.  
  9. Remove the flexible coupling pinch bolt and remove the coupling from the steering gear wormshaft.
  10.  

To install:
  1. Install the flexible coupling onto the steering gear wormshaft, aligning the flat in the coupling with the flat on the shaft. Push the coupling onto the shaft until the wormshaft bottoms on the coupling reinforcement. Install the pinch bolt and torque to specifications. The coupling bolt must pass through the shaft undercut.
  2.  
  3. Place the steering gear in position, guiding the coupling bolt into the steering shaft flange.
  4.  
  5. Install the steering gear to frame bolts and tighten to specifications.
  6.  
  7. If flexible coupling alignment pin plastic spacers were used, make sure they are bottomed on the pins, torque the flange bolt nuts to specifications and then remove the plastic spacers.
  8.  
  9. If flexible coupling alignment pin plastic spacers were not used, center the pins in the slots in the steering shaft flange and then install and torque the flange bolt nuts to specifications.
  10.  

SEAL REPLACEMENT



See Figure 4



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Fig. Fig. 4: Pitman shaft seal replacement

A faulty seal may be replaced without removal of steering gear by removing Pitman arm as outlined earlier and proceed as follows:

  1. Rotate the steering wheel from stop to stop, counting the total number of turns. Then turn back exactly half-way, placing the gear on center (the wormshaft flat should be at the 12 o'clock position).
  2.  
  3. Remove the three self-locking bolts attaching side cover to the housing and lift the Pitman shaft and side cover assembly from the housing.
  4.  
  5. Pry the Pitman shaft seal from the gear housing using a screwdriver and being careful not to damage the housing bore.
  6.  
  7. Coat the new Pitman shaft with Steering Gear Lubricant meeting GM Specification GM4673M (or equivalent). Position the seal in the Pitman shaft bore and tap into position using a suitable size socket.
  8.  
  9. Remove the lash adjuster lock nut. Remove the side cover from the Pitman shaft assembly by turning the lash adjuster screw clockwise.
  10.  
  11. Place the Pitman shaft in the steering gear such that the center tooth of the Pitman shaft sector enters the center tooth space of the ball nut.
  12.  
  13. Fill the steering gear housing with Steering Gear Lubricant meeting GM Specification GM4673M (or equivalent).
  14.  
  15. Install a new side cover gasket onto the gear housing.
  16.  
  17. Install the side cover onto the lash adjuster screw by reaching through the threaded hole in the side cover with a small screwdriver and turning the lash adjuster screw counterclockwise until it bottoms and turns back in 1 / 4 turn.
  18.  
  19. Install the side cover bolts and torque to specifications.
  20.  
  21. Install the lash adjuster screw locknut, perform steering gear adjustment and install the Pitman arm.
  22.  

 
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