Steering Gear - Manual GMC S15 Pickup

DESCRIPTION & OPERATION

Steering gear is a recirculating ball-type and consists of a ball nut connected to steering worm and in mesh with sector gear. Proper engagement between sector and ball nut is obtained by adjusting screw. Worm bearing adjuster can be turned to provide proper preloading of upper and lower bearings.

ADJUSTMENT PROCEDURES

Note. Adjust worm bearing preload prior to performing over-center preload adjustment. If steering gear is removed, install INCH lb. torque wrench on worm shaft to check preload adjustments.

WORM BEARING PRELOAD

1. Place reference marks on pitman arm and sector shaft. Using Pitman Arm Remover (J-6632-01), remove pitman arm from sector shaft. Loosen worm bearing adjuster lock nut. Back off worm bearing adjuster 1/4 turn. (Scheme 1) CAUTION: DO NOT turn wheel hard against stop with steering linkage disconnected or steering gear may be damaged.
2. Remove horn button. Turn wheel to the right stop and back off 1/2 turn. Install INCH lb. torque wrench on steering shaft nut. Rotate steering shaft through 90 degree arc and note torque wrench reading.
3. Torque required to maintain wheel movement should be 5-8 INCH lbs. (.5-.9 N.m). If not within specification, tighten worm bearing adjuster clockwise to increase preload or counterclockwise to decrease preload.
4. Adjust and hold worm bearing adjuster while tightening lock nut. Recheck worm bearing preload.

OVER-CENTER PRELOAD

1. With worm bearing preload adjusted, turn worm shaft slowly from stop-to-stop while counting total number of turns. Turn shaft back to the exact center position.
2. Loosen lock nut and turn sector shaft adjuster screw (located in center of sector shaft cover) in until all lash is taken out of sector shaft. Tighten lock nut. Rotate worm shaft slightly off center then attach an INCH lb. torque wrench to worm shaft or steering wheel nut.
3. Rotate worm shaft back through center position and note rotating torque. Rotating torque should be 4-10 INCH lbs. (.4-1.1 N.m) in excess of worm bearing preload. Maximum torque should not exceed 16 INCH lbs. (1.8 N.m). If rotating torque is not within specification, adjust sector shaft adjuster screw.

Scheme 1

TROUBLE SHOOTING

Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

Note. All steering component fasteners are made of special quality materials. Replacement fasteners must be of same part number or equivalent. Torque all fasteners and install new cotter pin when used.

Removal & Installation

1. Set front wheels in straight-ahead position. Disconnect negative battery cable. Remove flexible coupling cover (if equipped). Remove flexible coupling-to-steering shaft pinch bolt. Place reference marks on coupling and shaft for reassembly reference.
2. Mark relationship of pitman arm-to-sector shaft. Remove pitman arm retaining nut. Remove pitman arm using Puller (J-6632-01). Remove steering gear mounting bolts and remove gear assembly.
3. To install, reverse removal procedure. Ensure all reference marks are aligned and flexible coupling pinch bolt is aligned with groove of the shaft.

SECTOR SHAFT SEAL

Note. All steering component fasteners are made of special quality materials. Replacement fasteners must be of same part number or equivalent. Torque all fasteners and install new cotter pin when used.

Removal

1. Seal may be replaced with steering gear installed. Set front wheels in straight-ahead position. Mark relationship of pitman arm-to-sector shaft. Remove pitman arm using Puller (J-6632-01).
2. Remove sector shaft cover bolts. Lift sector shaft and side cover assembly from housing. Pry sector shaft seal from housing using a screwdriver. Be careful not to scratch housing bore.
3. Inspect gear lubricant for contamination. If lubricant is contaminated in any way, gear should be completely rebuilt.

Installation

1. Lubricate new sector shaft seal with steering gear lubricant. Position seal in sector shaft bore and tap it into place using a socket.
2. Remove sector shaft adjuster screw lock nut. Remove sector shaft cover from sector shaft assembly by turning adjuster screw clockwise. Install sector shaft in gear so center tooth of sector enters center tooth space of ball nut.
3. Fill gear housing with lubricant and install new side cover gasket on gear housing. Install side cover over sector shaft by reaching through cover hole with a screwdriver.
4. Turn sector shaft adjuster screws counterclockwise until screw bottoms and then back off screw 1/4 turn. Install sector shaft cover bolts and sector shaft adjuster lock nut. Adjust worm bearing preload and over-center preload. Refer to the «WORM BEARING PRELOAD»(/gmc/s15-pickup/1987-1991/remont/steering-gear/#steering-gear-manual__worm-bearing-preload) and «OVER-CENTER PRELOAD»(/gmc/s15-pickup/1987-1991/remont/steering-gear/#steering-gear-manual__over-center-preload) adjustment procedures at the beginning of this article.

DISASSEMBLY

1. Place steering gear in a vise, clamping onto one mounting tab. Worm shaft should be in a horizontal position. Rotate worm shaft from stop-to-stop while counting total number of turns. Turn shaft back to the exact center position.
2. Loosen sector shaft adjuster screw lock nut. Remove sector shaft cover bolts. Lift sector shaft cover and sector shaft from housing.
3. Loosen worm bearing adjuster lock nut. Remove worm bearing adjuster with bearing and bearing race. (Scheme 1) Remove ball nut and worm shaft assembly. CAUTION: DO NOT allow ball nut to rotate down to either end of worm shaft, as ball guide ends may be damaged.
4. Remove remaining bearing from housing. Using screwdriver, pry bearing retainer from worm bearing adjuster assembly and remove bearing. Remove sector shaft adjuster screw lock nut.
5. Hold sector shaft cover and turn sector shaft adjuster screw clockwise to remove sector shaft cover. Remove sector shaft adjuster screw and shim from sector shaft. Pry out and discard both sector shaft and worm shaft seals.

CLEANING & INSPECTION

Clean components with solvent and dry with compressed air. Inspect bearings and races for signs of wear. Inspect sector shaft fit at side cover. Check ball nut and worm shaft assembly for wear and straightness.

Sector Shaft Bearing Replacement

Support steering gear in an arbor press. Using Bearing Remover (J-6278), drive sector shaft bearing from housing. Using Bearing Installer (J-35469 and J-8092), install new bearing into housing. Replacement bushings are machined to size and require no reaming.

Worm Shaft Bearing Race (In Worm Bearing Adjuster)

Using Slide Hammer (J-29369-1), remove bearing race from worm bearing adjuster. Using Bearing Race Installer (J-35365), install bearing race in worm bearing adjuster.

Worm Shaft Bearing Race (In Housing)

Using a hammer and punch, remove bearing race from housing. Using Bearing Race Installer (J-35365), install new bearing race in housing.

Ball Nut & Worm Shaft Assembly

Ball nut disassembly is necessary only if binding or tightness exists while rotating worm shaft. If disassembly is required, proceed to step 1).

1. Several balls will be removed; ensure there is proper area to catch balls. Remove ball guides retaining clamp. Pull guides from ball nut while catching balls in clean pan. Turn nut over and rotate worm shaft until all balls have been removed.
2. Remove worm shaft from the ball nut. Wash parts and inspect worm, nut grooves, and ball bearings for indentations. Check ball guides for damage at ends where they deflect or pick up balls from helical path on worm shaft.
3. Measure distance between ball grooves of worm gear. Distance between grooves determines amount of balls to be installed in each circuit. See «BALL USAGE»(/gmc/s15-pickup/1987-1991/remont/steering-gear/#steering-gear-manual) table. BALL USAGE Groove Distance:P In. (mm) Balls Per Circuit .04 (1.0) 25 .10 (2.5) 27 .20 (5.0) 27
4. To reassemble ball nut and worm shaft, install ball nut with narrow end of ball nut teeth upward on right side (looking from steering wheel end of worm shaft). Install worm shaft. Ensure worm shaft is aligned with grooves in ball nut.
5. Install guides in ball nut. Install proper amount of balls in one guide hole while rotating the worm shaft. Repeat procedure for the remaining guide. Install guide clamps and bolts.

REASSEMBLY

1. Place gear housing in a vise with worm shaft bore horizontal and side cover opening facing upward. All seals, bushings and worm shaft bearing races should be installed.
2. Place upper ball bearing over worm shaft. Install worm shaft and ball nut assembly into housing and up through the upper ball bearing race and seal. Install bearing and retainer in worm bearing adjuster.
3. Install worm shaft and worm bearing adjuster in housing. Tighten worm bearing adjuster until a very slight amount of worm shaft end play exists. Install sector shaft adjuster screw and shim in slotted end of sector shaft.
4. Using feeler gauge, check clearance between adjuster screw and sector shaft when holding adjuster screw upward. Clearance should not exceed .002" (.05 mm). If clearance exceeds specification, a different thickness shim should be installed.
5. Rotate worm shaft until ball nut is at center of its travel. Install sector shaft assembly so center tooth of sector teeth enters center tooth space in ball nut.
6. Install side cover gasket. Install side cover over sector shaft by reaching through cover with a screwdriver.
7. Turn adjuster screw counterclockwise until screw bottoms and then back off screw 1/2 turn. Loosely install a new lock nut onto adjuster screw.
8. Install sector shaft cover bolts. Adjust worm bearing preload and over-center preload. Refer to the «WORM BEARING PRELOAD»(/gmc/s15-pickup/1987-1991/remont/steering-gear/#steering-gear-manual__worm-bearing-preload) and «OVER-CENTER PRELOAD»(/gmc/s15-pickup/1987-1991/remont/steering-gear/#steering-gear-manual__over-center-preload) adjustment procedures at the beginning of this article.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• WORM BEARING PRELOAD
• OVER-CENTER PRELOAD
• BALL USAGE