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.
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 prload 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
- 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.
- Using a hammer and a brass punch, drive the adjuster plug locknut counterclockwise and remove it from the end of the steering gear.
- 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).
- Use a scribing tool to place a matchmark (on the housing) next to the one of the spanner wrench holes in the adjuster plug.
- Using a ruler, measure 1 / 2 in. (13mm) counterclockwise from the scribed mark (on the housing) and place another mark.
- Use the spanner to turn the adjuster plug (counterclockwise) until the hole in the adjuster plug aligns with the 2nd scribed mark.
- While holding the adjuster plug in alignment, install and tighten the adjuster plug locknut.
- Perform the overcenter preload adjustment.
See Figures 5, 6 and 7
- Adjust the worm bearing preload. For details, please refer to the procedure earlier in this section.
- Rotate the stub shaft from stop-to-stop and count the number of turns necessary.
- Starting from one stop, turn the stub shaft back 1 / 2 the number of turns (to the center of the gear).
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.
- Loosen the pitman shaft adjuster screw locknut, then turn the adjuster screw counterclockwise until it is fully extended. Turn the screw clockwise one full turn.
- 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.
- Turn the adjuster screw inward until the torque on the stub shaft is 6-10 inch lbs. (0.6-1.2 Nm) greater than the initial reading.
- Tighten the adjuster screw jam nut to 20 ft. lbs. (27 Nm) while holding the adjuster screw from turning. Double check for the proper measurement to assure the screw was not turned while tightening the nut.
- Install the power steering gear into the vehicle.
REMOVAL & INSTALLATION
- Raise and support the front of the vehicle safely using jackstands.
- For MFI-Turbo vehicles, drain the charge air cooler system and remove the charge air cooler radiator. For details, please refer to Chapter 3 of this manual.
- Position a fluid catch pan under the power steering gear.
- Disconnect the feed and return fluid hoses from the steering gear. Immediately cap or plug all openings to prevent system contamination or excessive fluid loss.
Be sure to plug the pressure hoses and the openings of the power steering pump to keep dirt out of the system.
- On late model vehicles (or if equipped) remove the intermediate shaft lower coupling shield.
- Remove the intermediate shaft-to-steering gear bolt. Matchmark the intermediate shaft-to-power steering gear and separate the shaft from the gear.
- Matchmark and remove the pitman arm from the gear pitman shaft. For details, please refer to the procedure earlier in this section.
- Remove the power steering gear-to-frame bolts and washers, then carefully remove the steering gear from the vehicle.
- Position the steering gear to the vehicle and secure by finger-tightening the fasteners. For some late model vehicles, the pitman arm must be connected to the gear while it is still removed from the vehicle or while it is partially installed and lowered for access. If necessary, align and install the pitman arm to the shaft at this time.
- Torque the power steering gear-to-frame bolts to 55 ft. lbs. (75 Nm).
- Align and install the intermediate shaft to the power steering, then secure using the pinch bolt.
- If equipped, install the shield over the intermediate shaft lower coupling.
- Remove the caps, then connect the feed and return hoses to the power steering gear. Refill the pump reservoir.
- On MFI-Turbo vehicles, install the charge air cooler radiator.
- Remove the jackstands and carefully lower the vehicle.
- On MFI-Turbo vehicles, properly refill and bleed the charge air cooler system.
- Properly bleed the power steering system.
- Road test the vehicle.