Adjust the manual steering box sector shaft lash to eliminate steering wheel free play and ensure proper steering response on the 1966 Corvette.

Warnings

Tools required

Parts

• Sector shaft adjustment screw locknut × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and apply parking brake
2. Chock rear wheels securely
3. Raise front of vehicle and support on jack stands at frame rails
4. Remove front wheels to allow full steering lock access (optional but recommended)
5. Turn steering wheel to center position and verify front wheels are straight ahead
6. Check steering box mounting bolts are tight to frame rail before adjustment

Procedure

1. 1

   Locate the steering box adjustment screw
   The steering box is mounted on the driver side frame rail. Locate the sector shaft adjustment screw on top of the steering box housing. It is a slotted screw with a locknut, positioned at the top center of the box where the pitman arm shaft exits.
2. 2

   Check initial steering play
   With the steering wheel centered, gently rock the steering wheel back and forth. Note the amount of free play at the rim. Acceptable free play is approximately 1/2 to 1 inch measured at the steering wheel rim. Excessive play (more than 1.5 inches) indicates adjustment is needed.
3. 3

   Loosen the adjustment screw locknut
   Using the correctly sized box-end wrench, loosen the locknut on the sector shaft adjustment screw. Turn counterclockwise approximately 1 full turn. Do not remove the locknut completely. The locknut is located directly around the adjustment screw shaft.
4. 4

   Turn steering to full left lock
   Rotate the steering wheel fully to the left (counterclockwise) until it stops. Count the total number of turns from center. This establishes the full range of travel. Do not force the wheel past the stop.
5. 5

   Turn steering to full right lock and count turns
   Rotate the steering wheel fully to the right (clockwise) from the left lock position. Count the total turns of the steering wheel. Note the total turns lock-to-lock for your specific box (the standard 1966 Corvette manual box is approximately 3.4 turns, but a quick-ratio box will differ). Use the actual measured count for centering in the next step.
6. 6

   Center the steering box
   From the full right lock position, turn the steering wheel back to the left exactly half the number of turns counted in the previous step. This places the sector shaft in the true center (high spot) position where adjustment is made.
7. 7

   Perform initial sector shaft adjustment
   Using a large flat blade screwdriver, turn the sector shaft adjustment screw clockwise (inward) until you feel a definite increase in resistance or slight bind at the center position. Turn the screw in small increments (1/8 turn at a time). This takes up the lash between the sector shaft teeth and the ball nut.
8. 8

   Back off the adjustment screw
   Once you feel resistance or binding at center, back the adjustment screw out (counterclockwise) exactly 1/4 to 1/2 turn. This provides the proper amount of lash. The steering should feel snug at center with no binding when rotated through the center position.
9. 9

   Test steering effort through full range
   While holding the adjustment screw with the screwdriver to prevent it from turning, rotate the steering wheel slowly from full left to full right lock. The steering should move smoothly without binding at any point. There should be slightly less play at center than at the extremes, but no tight spots or binding.
10. 10

    Tighten the locknut
    While holding the adjustment screw firmly in position with the screwdriver, tighten the locknut with the correctly sized box-end wrench. Tighten securely but do not overtighten. Tighten the locknut securely to the factory specification while holding the adjuster screw stationary (confirm exact torque value from the GM service manual before final tightening). Verify the adjustment screw did not turn while tightening the locknut.
11. 11

    Recheck steering play at center
    Center the steering wheel again and check for free play. There should be approximately 1/4 to 1/2 inch of free play measured at the steering wheel rim at the center position. Rotate the wheel lock-to-lock again to verify smooth operation with no binding.
12. 12

    Road test verification
    After reinstalling wheels (if removed) and lowering the vehicle, perform a careful road test at low speed in a safe area. Verify steering returns to center properly after turns, there is no binding or tight spots, and steering feel is appropriate with minimal free play at center. Re-adjust if necessary.

Reassembly

1. Reinstall front wheels if removed and torque lug nuts to specification
2. Lower vehicle from jack stands
3. Remove wheel chocks
4. Check steering box for any signs of gear oil leakage around the adjustment screw
5. If leakage is present, the adjustment screw seal may need replacement

Verification

• With engine off and vehicle stationary, steering wheel free play at rim should be 1/4 to 1/2 inch at center position
• Steering should rotate smoothly lock-to-lock with no binding or tight spots
• Steering wheel should return to center readily after completing a turn
• No unusual noises from steering box during operation
• Pitman arm should move proportionally with steering wheel input with no delay or looseness

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