Steering System - Power GMC Sonoma Syclone

DESCRIPTION

Steering gear is a variable ratio, recirculating ball type. The wormshaft is supported at the lower end by a thrust bearing with 2 races. It is supported at the upper end by a bearing assembly in the adjuster plug. Control valves, located inside steering gear housing, direct power steering fluid to either side of rack piston. A 4-character build date is stamped on the cover. (Scheme 2)

TROUBLE SHOOTING

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

LUBRICATION & TESTING

For lubrication and testing, see appropriate POWER STEERING GENERAL SERVICING article in the STEERING section.

Scheme 2

Note. Replace idler arm assembly if an up and down force (forward and rearward on "G" Series) of 25 lbs. (11 kg), applied at relay rod end of idler arm, produces a lash of more than 1/8" (3 mm) in straight-ahead position.

STEERING SERVICE PRECAUTIONS

Replacement fasteners must be of same part number as original. Tighten all fasteners to specification. Always use NEW cotter pins. When installing cotter pins, DO NOT back off castle nuts to align cotter pin hole. Tighten nut to next slot that lines up with hole.

DO NOT hammer on ball studs, or damage to threads may result. If threads are not clean and smooth, ball studs may turn in joint when nuts are tightened. Position tie rod sleeve clamps as specified before tightening bolts. (Scheme 5)

THRUST BEARING PRELOAD

1. Remove steering gear from vehicle. See removal & installation section. Rotate gear lock-to-lock several times to drain fluid. Loosen adjuster plug lock nut. Using spanner wrench, turn adjuster plug clockwise until plug is seated in housing. Torque should be approximately 20 ft. lbs. (27 N.m).
2. Index mark housing opposite one hole in adjuster plug. (Scheme 3) Measure about 1/2" counterclockwise from mark. Mark housing. Rotate plug counterclockwise until hole in adjuster aligns with second mark.
3. Tighten lock nut. Ensure adjuster plug remains in position. Attach INCH lb. torque wrench to end of stub shaft. Turn stub shaft to right stop, then back 1/4 turn.
4. Using torque wrench, measure rotational torque required to turn shaft. Reading should be taken with handle of torque wrench near vertical while turning it counterclockwise at an even rate. Reading should be 4-10 INCH lbs. (.4-1.1 N.m). If not, repeat procedure.

Scheme 3

OVER-CENTER PRELOAD

Note. Adjust thrust bearing preload before adjusting over-center preload.

1. Ensure steering gear is centered. Loosen pitman shaft adjuster screw lock nut. Tighten pitman shaft lash adjuster screw. Retighten lock nut. Measure gear over-center torque by rotating torque wrench attached to stub shaft in a 90 degree arc, 45 degrees on each side of center. Record highest degree of arc on each side of center. Record highest reading.
2. Continue adjustment until over-center reading is within specification. See «LASH ADJUSTMENT PRELOAD»(/gmc/sonoma-syclone/1991-1992/remont/manual-power-steering/#steering-system-power) below. Ensure lock nut is tight when reading is obtained. (Scheme 4)

LASH ADJUSTMENT PRELOAD

Scheme 4

Removal

1. Center steering gear. If necessary, remove steering column for clearance. Raise and support vehicle. Place drain pan under steering gear assembly. Disconnect hydraulic hoses from gear and cap ends. Remove lower clamp bolt and shield from steering shaft (if equipped). Mark alignment of clamp to steering shaft before removing bolt.
2. Remove universal yoke-to-shaft bolt. Disconnect universal yoke from shaft. Disconnect steering linkage from pitman arm. Remove pitman arm from gear. Remove flexible coupling clamp nuts (if equipped). Remove flexible coupling clamp pinch bolt (if equipped).
3. On "P" Series, remove flexible coupling-to-steering shaft flange bolts. Remove steering gear-to-frame bolts. Remove gear from flexible coupling and frame.

Installation

To install, reverse removal procedures. On "P" Series vans, maintain the coupling-to-steering shaft flange dimension of .25-.37" (6.4-9.5 mm). Tighten bolts and nuts to specifications. Refer to the TORQUE SPECIFICATIONS table. Fill pump reservoir. Bleed air from system. See POWER STEERING GENERAL SERVICING article in the STEERING section.

Raise and support vehicle. Remove cotter pins and outer tie rod end nut. Using Wheel Stud and Tie Rod Remover (J-6627-A), remove outer tie rod ball studs from steering knuckle. Remove inner tie rod ball studs from relay rod. Remove tie rod ends from adjuster tube. Loosen clamp bolts and unscrew assemblies.

To install, reverse removal procedure. Lubricate tie rod threads with chassis lubricant before installing. Inner and outer tie rod end threads must be installed equally within 3 threads. Adjust toe-in. See WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in the WHEEL ALIGNMENT section. Tie rod ends must rotate full travel and travel must be maintained during clamp tightening. (Scheme 5)

Scheme 5

Raise and support vehicle. Remove inner tie rod end nuts. Remove inner tie rod ends from relay rod. On "C" & "K" Series and "T" Series, remove steering damper nut from relay rod . Using Steering Linkage Puller (J-24319-01), remove steering damper from relay rod. Remove relay rod end nuts from pitman arm and idler arm. Using Steering Linkage Puller (J-24319-01), remove pitman arm and idler arm from relay rod. Remove relay rod.

To install, reverse removal procedure. Using Steering Linkage Installer (J-29193 or J-29194), seat all tapers to 40 ft. lbs. (54 N.m). Tighten nuts to specifications. See TORQUE SPECIFICATIONS table. Adjust toe-in. See the WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in the WHEEL ALIGNMENT section.

IDLER ARM

Note. Replace idler arm assembly if an up and down force (forward and rearward on "G" Series) of 25 lbs. (11 kg), applied at relay rod end of idler arm, produces a lash of more than 1/8" (3 mm) in straight-ahead position.

Raise and support vehicle. Remove idler arm nut and bolt from tie rod end. Remove idler arm nut and spring washer from relay rod. Using Steering Linkage Puller (J-24319-01), remove idler arm from relay rod. Remove idler arm. (Scheme 6)

To install, reverse removal procedure. Using Steering Linkage Installer (J-29193 or J-29194), seat all tapers to 40 ft. lbs. (54 N.m). Tighten nuts to specifications. See TORQUE SPECIFICATIONS table. Adjust toe-in. See the WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES in the WHEEL ALIGNMENT section.

Scheme 6

Place vehicle on hoist. Remove cotter pin and nut from ball stud. Using Steering Linkage Puller (J-24319-01), remove pitman arm from ball stud. Remove pitman arm nut and washer from shaft or clamp bolt from pitman arm. Index mark arm-to-shaft position. Using Puller (J-6632-01), remove pitman arm from shaft.

To install, reverse removal procedure. If a clamp-type pitman arm is used, spread pitman arm with a wedge just enough to slip arm onto shaft by hand pressure. DO NOT hammer on pitman arm, or damage to steering gear may result. Be sure to reinstall hardened steel washer before installing nut.

Remove air induction duct assembly. Slide intermediate shaft cover up and mark the relationship of the intermediate shaft. Remove the intermediate shaft. Disconnect oil filter lines at the crossmember bracket. Remove splash shield, pitman arm ball stud nut and spring washer, pitman arm ball stud from the relay rod using J 24319-01. Remove two lower steering gear bolts, loosen ( DO NOT remove) upper steering gear bolt, rotate the steering gear for pitman arm clearance at the frame crossmember and support it with a small block of wood. Remove the pitman arm nut and spring washer, mark the pitman arm and the pitman shaft. This will permit proper alignment at assembly.

Note. DO NOT hammer on the pitman arm, pitman shaft, or puller. Damage to the pitman arm or steering gear may result.

Remove pitman arm, use J 6632-01 or J 29107.

Install pitman arm on the pitman shaft. Use J 29194, line up the marks that were made before removal. Install spring washer and nut. Tighten the nut to 185 ft.lbs. (250 N.m), rotate the steering gear back to proper position and remove the block of wood. Install steering gear bolts and tighten to 55 ft.lbs (75 N.m). Install pitman arm ball stud to the relay rod using tool J 29193. Install pitman arm ball stud nut and spring washer, and tighten the nut to 60 ft.lbs (82 N.m). Install splash shield. Reconnect oil filter lines to the crossmember bracket. Install intermediate shaft. Line up the marks made at removal, slide the intermediate shaft cover down. Install air induction duct assembly.

Removal (4WD Models)

Remove cotter pins from ball studs. Remove castle nuts. Using Steering Linkage Puller (J-24319-01), remove ball studs from steering arm and pitman arm. Mark position of adjuster tube and direction of bolt installation. Remove connecting rod ends from adjusting tube. Loosen clamp bolts. Remove connecting rod ends.

To install, reverse removal procedure. Ensure threads on studs and nuts are clean and smooth. Check ball stud seals. Replace seals (if necessary). Inner and outer tie rod end threads must be installed equally within 3 threads. Install connecting rod on steering components. Tighten nuts. Install NEW cotter pins. Ensure connecting rod clamps are properly aligned.

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Disassembly

1. Cap all openings in gear. Clean gear exterior completely. Mount gear in vise so that pitman shaft points downward. Rotate housing end plug retainer ring until one end of plug is over hole in housing.
2. Force end of ring from groove in housing. Remove ring. Rotate stub shaft counterclockwise to force housing end plug from housing. Rotate stub shaft 1/2 turn clockwise to draw rack piston inward. CAUTION: DO NOT rotate stub shaft more than necessary to remove plug, as ball bearings will fall out of worm and rack piston assembly.
3. Remove rack piston end plug. Remove lock nut from pitman shaft adjuster. Remove pitman shaft cover. Remove and discard "O" ring or gasket from cover. Turn stub shaft until pitman shaft teeth are centered in housing.
4. Using a soft-faced hammer, tap end of pitman shaft to free shaft from housing. Remove pitman shaft. Remove adjuster plug lock nut. Using a spanner wrench, remove adjuster plug.
5. Insert Rack Piston Arbor (J-21552) into end of rack piston assembly until arbor just contacts worm shaft. Threaded arbor will keep recirculating balls from falling out of rack piston. Turn stub shaft counterclockwise to force rack piston onto arbor. Remove rack piston and arbor as an assembly.
6. Ensure arbor is fully inserted so recirculating balls will not fall out. Remove stub shaft and control valve assembly from housing. Remove worm, wormshaft lower thrust bearing, and races from housing.

Inspection

1. Clean all internal parts in solvent and dry with compressed air. Avoid wiping valve parts with cloth. Lint may cause binding of mechanism.
2. DO NOT steam clean hydraulic parts. If further disassembly is required, see appropriate component in «OVERHAUL»(/gmc/sonoma-syclone/1991-1992/remont/manual-power-steering/#steering-system-power) section in this article.

Reassembly

1. Lubricate all parts with power steering fluid before reassembly. Install lower thrust bearing and races on worm shaft. (Scheme 2) NOTE: If conical thrust races are used, ensure tapered surfaces are parallel to each other and that cupped sides face toward stub shaft.
2. Place worm shaft in valve body. Install "O" ring in valve body. Align notch in valve body with pin in worm shaft. Install valve body and worm assembly into housing. Installation is correct when fluid return port in housing is fully visible.
3. Place seal protector over stub shaft. Using new "O" ring, install adjuster plug until it seats against valve body.
4. Remove seal protector from housing. Loosely install adjuster plug lock nut. Insert rack piston (with arbor to retain recirculating balls) into housing. Align worm and rack piston. Turn stub shaft clockwise to engage worm. Maintain pressure on arbor until worm is fully engaged.
5. Rotate stub shaft clockwise to align middle rack groove in rack piston with center of pitman shaft roller bearing. Remove arbor. Install a new pitman shaft cover seal.
6. Thread pitman shaft cover onto adjuster screw until it bottoms. Back off 1/2 turn. Install pitman shaft so that center gear tooth meshes with center groove in rack piston. Install cover attaching bolts.
7. Install adjuster lock nut halfway onto pitman shaft. Install piston and plug in rack piston. Install housing end plug "O" ring, end plug and retainer ring. Adjust thrust bearing preload and over-center preload. See «ADJUSTMENT»(/gmc/sonoma-syclone/1991-1992/remont/manual-power-steering/#steering-system-power) section.

Using Spanner Wrench (J-7624), remove adjuster plug valve assembly. Remove retaining ring using a snap ring pliers. Using a screwdriver, pry bearing retainer at the raised area. Discard retainer. Remove seal and needle bearing (if necessary). (Scheme 2)

Inspect bearing for cracks. Check for pitting, scoring, or cracking. Check thrust races and spacer for damage. Replace parts as necessary.

1. Using adjuster plug Bearing Installer (J-8524-1) and Driver (J-7079-2), seat needle bearing in adjuster plug assembly. Lubricate oil seal with power steering fluid. Install oil seal, washer and retaining ring into adjuster plug.
2. Ensure retainer projections must not extend beyond washer, when retainer ring is seated. Washer must be free to rotate.

If installed, remove Rack Piston Arbor (J-21552) from rack piston. If arbor is not used, remove worm shaft, lower thrust bearing and bearing races from rack piston. Remove piston ring and back-up "O" ring from rack piston. Remove ball guide clamp and ball guides. Remove all recirculating balls from rack piston.

1. Clean and dry all parts. Inspect worm shaft and rack piston grooves for scoring. Inspect ball bearings for damage. If any ball bearings are damaged, replace entire set. Check ball guides for pinching of ends.
2. Inspect lower thrust bearing races for cracking, scoring, or pitting. If either part is damaged, replace wormshaft and rack piston as an assembly. Inspect rack piston teeth for chips, cracks, dents or scoring.

1. Lubricate Teflon seal and "O" ring with power steering fluid and carefully install onto rack piston. Install worm shaft into rack piston until worm shaft touches piston shoulder. While turning worm shaft counterclockwise, insert ball bearings into rack piston. NOTE: See «RACK PISTON & WORM ASSEMBLY BALL BEARINGS TABLE»(/gmc/sonoma-syclone/1991-1992/remont/manual-power-steering/#steering-system-power) for number of balls to be installed. ENSURE light and dark colored balls are installed alternately, as Black balls are.0005" (.013 mm) smaller than Silver balls.
2. Install correct number of balls in ball guide, alternating ball colors. Bearings in guide must be in sequence with bearings in rack piston. Hold balls in place with chassis lubricant. Install return ball guide assembly into position.
3. Install clamp. Tighten cap screws. (Scheme 14) Insert Rack Piston Arbor (J-21552) into rack piston until it contacts worm shaft. Maintain pressure on arbor, and back worm out of rack piston. DO NOT allow ball bearings to drop out.

RACK PISTON & WORM ASSEMBLY BALL BEARINGS

Scheme 14

Scheme 15

1. Remove and discard stub shaft cap "O" ring. Lightly tap end of stub shaft against wood block until shaft cap is free of valve body. Pull stub shaft outward until drive pin hole is visible. (Scheme 15) CAUTION: DO NOT pull shaft more than 1/4" (6 mm) or spool valve may become cocked in valve body.
2. Disengage drive pin. Remove stub shaft from valve body and spool assembly with a twisting motion. If binding occurs, realign valve. CAUTION: DO NOT force stub shaft or spool out of valve body.
3. Remove spool valve from valve body with twisting motion. Remove and discard all "O" rings and Teflon rings.

1. Wash all parts in solvent and blow dry. Check for leaks between stub shaft and torsion bar. Check for nicks and scores on stub shaft. Sand down with Crocus cloth if possible. Check notch valve body skirt for wear.
2. Check spool valve fit in valve body. With "O" ring removed, lubricate spool valve with power steering fluid. Rotate spool valve in valve body. If valve does not rotate freely, replace complete valve.
3. Valve assembly is balanced during assembly. If replacing any parts other than rings or seals, replace complete assembly.

1. Lubricate valve body components with power steering fluid. Install new "O" rings in seal grooves. Install new Teflon rings over "O" rings. Take care not to damage seal rings during installation. NOTE: Teflon seal rings may appear to be distorted after installation. However, heat of operation will straighten them.
2. Lubricate replacement spool valve damper "O" ring with petroleum jelly and install on spool valve. Carefully insert spool valve into valve body.
3. Push spool valve through valve body until locating pin hole is visible at opposite end of valve body, and spool valve is flush with notched end of valve. Install stub shaft into spool valve and valve body.
4. Align stub shaft locating pin with spool valve locating hole. Align notch in stub shaft cap with pin in valve body. Press stub shaft and spool valve into valve body. Install stub shaft cap "O" ring into valve body.

1. Remove pitman shaft seal snap ring. Remove seals and washers. (Scheme 2) Press pitman shaft bearing out of housing from lower end.
2. If hose connector seat is being replaced, tap seat with a 5/16" x 18 thread tap. Thread connector seats ONLY 2-3 threads. Install bolt with flat washer and nut into seat. Hold bolt while tightening nut to extract seat.

1. If housing bore is severely worn, scored or pitted, replace housing. Minor scratches may be removed with crocus cloth.
2. Inspect all retaining ring, bearing and seal surfaces in housing. If any surface is worn or damaged, replace housing.

1. Install pitman shaft bearing in steering housing using Handle (J-8092) and Adapter (J-22407). Position bearing so identification marks face away from tool. Press bearing in until tool bottoms against housing. DO NOT bottom bearing in housing.
2. Install seals with lips facing toward housing bore. Install snap ring.

WHEEL ALIGNMENT

After performing appropriate service procedures, refer to the WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in the WHEEL ALIGNMENT section.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES
• POWER STEERING GENERAL SERVICING
• WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES
• LASH ADJUSTMENT PRELOAD