Power Steering Gear Box

Remove and replace the power steering gear box on a 1966 Corvette with 327ci V8, including fluid drainage, pitman arm separation, and system refill.

Warnings

Tools required

Parts

• Power steering gear box × 1 — Use OEM specification or quality remanufactured unit
• Pitman arm seal × 1 — Use OEM specification
• Gear box mounting bolts (if corroded) × 3 — Use OEM specification
• Hydraulic line crush washers × 2 — Use OEM specification

Fluids

• GM Power Steering Fluid — 1 qt

Preparation

1. Park vehicle on level surface and set parking brake firmly
2. Disconnect negative battery cable to prevent accidental starter engagement
3. Raise front of vehicle with floor jack and secure on jack stands under frame rails
4. Turn steering wheel to center position and mark steering wheel position with tape
5. Remove front splash shields or belly pan if equipped
6. Clean area around gear box and hydraulic fittings with wire brush to prevent contamination

Procedure

1. 1

   Drain power steering reservoir
   Using a turkey baster or suction tool, remove as much fluid as possible from the power steering reservoir mounted on the pump. Dispose of old fluid properly in a sealed container. This minimizes spillage when disconnecting lines.
2. 2

   Disconnect hydraulic lines from gear box
   Position drain pan beneath gear box. Using flare nut wrenches if available, disconnect the high-pressure line from the input port on the gear box. The fitting requires a 5/8" wrench on the line and a 3/4" wrench to hold the gear box port. Disconnect the return line from the output port using the same technique. Allow fluid to drain completely. Cap or plug the lines and ports to prevent contamination.
3. 3

   Mark pitman arm orientation
   Using a scribe, paint marker, or center punch, create alignment marks on both the pitman arm and the sector shaft where they mate. These marks are critical for maintaining proper steering alignment during reassembly. Verify whether the pitman arm and sector shaft have a master (blocked) spline that permits only one orientation; if so the marks provide visual confirmation, otherwise the alignment marks are critical for correct installation.
4. 4

   Remove pitman arm nut
   Remove the castellated nut securing the pitman arm to the gear box sector shaft. This nut requires a 1-1/8" socket or wrench. Remove and discard the cotter pin first. The nut torque from factory is significant, so use penetrating oil if the nut is seized.
5. 5

   Separate pitman arm from sector shaft
   Install the pitman arm puller onto the pitman arm per the tool manufacturer's instructions. The 1966 Corvette uses a standard taper fit. Tighten the puller screw while holding the puller body stable. Apply firm pressure until the taper releases with an audible pop. Do not strike the sector shaft with a hammer as this can damage the gear box internals. If the arm is extremely stubborn, apply additional penetrating oil and allow it to soak for 30 minutes.
6. 6

   Remove gear box mounting bolts
   Locate the 3 bolts securing the gear box to the frame rail on the driver side. These bolts pass through the gear box mounting flange and thread into the frame. Remove all 3 mounting bolts using a 9/16" socket with extension. Support the gear box with one hand as the last bolt is removed to prevent it from dropping.
7. 7

   Remove gear box from vehicle
   Maneuver the gear box out through the opening between the frame rail and engine. The sector shaft end exits first toward the driver side wheel well. The gear box weighs approximately 15 pounds. Tilt and rotate as needed to clear any obstructions. Once clear, set the old unit aside for core return if applicable.
8. 8

   Clean mounting surfaces
   Wire brush the frame rail mounting surface where the gear box flange mates. Remove all rust, old gasket material, and debris. Inspect the mounting bolt holes in the frame for stripped threads or damage. Chase threads with the appropriate tap if needed.
9. 9

   Prepare new gear box
   Remove shipping plugs or caps from the new or remanufactured gear box. Inspect the sector shaft splines for damage. Verify that the new unit turns smoothly by rotating the input shaft by hand through its full range. Check that the mounting flange holes align with your bolt pattern.
10. 10

    Install new gear box
    Guide the new gear box into position with the sector shaft exiting toward the driver side. Align the mounting flange with the frame rail holes. Start all 3 mounting bolts by hand to ensure proper thread engagement. Torque mounting bolts to 65 ft-lb in a cross pattern to ensure even clamping force.
11. 11

    Reinstall pitman arm
    Slide the pitman arm onto the sector shaft, aligning the scribe marks made during disassembly. If the shaft has a master (blocked) spline only one position is possible; otherwise rely on the scribe marks made during disassembly to ensure correct alignment. Install the castellated nut and torque to 185 ft-lb. Install a new cotter pin through the castellations and sector shaft hole, then bend the pin ends to secure.
12. 12

    Reconnect hydraulic lines
    Verify the line connection type; 1966 Saginaw fittings are typically inverted-flare seats (no crush washer) or use an O-ring on the pressure fitting. Replace O-rings or use inverted-flare seats as applicable rather than crush washers. Connect the high-pressure line to the input port on the gear box and torque per factory specification using a flare nut wrench to prevent rounding. Connect the return line to the output port and torque to the same specification. Ensure both fittings are snug but do not overtighten as this can damage the cast iron gear box housing.
13. 13

    Refill and bleed power steering system
    Fill the power steering reservoir with the specified power steering fluid (GM Type A ATF or modern GM power steering fluid as a substitute) to the full cold mark. Start the engine and allow it to idle. Turn the steering wheel slowly from lock to lock 10 times without holding at full lock. Check fluid level and add as needed. The system holds approximately 1 quart total. Continue turning lock to lock until no bubbles appear in the reservoir and the fluid level stabilizes. Top off to the full hot mark with engine at operating temperature.
14. 14

    Check for leaks and steering function
    With engine running, inspect all hydraulic connections at the gear box for leaks. Check the sector shaft seal for seepage. Turn the steering wheel through full range and verify smooth operation with no binding or unusual noises. Shut off engine and recheck all connection torques.

Reassembly

1. Reinstall front splash shields or belly pan if removed
2. Reconnect negative battery cable
3. Remove jack stands and lower vehicle to ground
4. Recheck power steering fluid level after initial test drive and top off if needed

Verification

• Start engine and verify no power steering fluid leaks at gear box or line connections
• Turn steering wheel lock to lock with engine running and verify smooth, quiet operation with no binding
• Test drive vehicle at low speed in a safe area to confirm proper steering response and returnability
• Verify steering wheel returns to center position after turns without binding
• Recheck all mounting bolt torques after test drive
• Check power steering fluid level after test drive and verify it remains at the full hot mark

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