Steering Gear - Manual Ford Bronco II I

DESCRIPTION & OPERATION

The steering gear is worm and recirculating ball-type. A ball nut is used which has threads that mate to threads of worm shaft via continuous rows of ball bearings. As steering wheel is rotated, worm shaft rotates, causing ball nut to move up or down worm shaft.

The gear teeth on ball nut are meshed with gear teeth on sector shaft. Thus, movement of ball nut causes sector shaft to rotate and swing pitman arm.

Proper mesh engagement between sector shaft and ball nut is obtained by an adjusting screw which moves sector shaft axially. Worm shaft thrust bearing adjuster can be turned to provide proper preloading of worm thrust bearings.

On Bronco II and Ranger there are 2 types of manual ball nut gears: a constant (24:1) ratio and a variable (20-24:1) ratio. Gears differ according to a model number stamped on sector cover. "SMK-A" designates a constant ratio gear, while a "SMK-B" code is a variable ratio gear.

On Pickup and Van there are also 2 types of manual ball nut gears: a long input shaft (designated "SMK-C") for Pickup and Van and a short input shaft (designated "SMK-D") for stripped chassis vehicles. Both models provide a variable (24-27:1) ratio and use common parts except for sector cover (identification only) and input shaft (worm shaft).

Koyo Recirculating Ball Steering Gear (Typical). Scheme 1

PRELIMINARY

1. Worm bearing preload must be adjusted before meshload. While meshload may be adjusted with steering gear installed, worm preload cannot be adjusted in vehicle.
2. Disconnect pitman arm at ball stud. Lubricate worm shaft seal with a drop of A/T fluid. Remove horn pad. Turn steering wheel slowly to one stop.
3. Measure amount of torque (preload) required to rotate steering wheel at a constant speed for approximately 1 1/2 turns. If preload is not within 2-6 INCH lbs. (2.2-6.8 N.m) on Bronco II and Ranger or 5-9 INCH lbs. (6.0-10.0 N.m) on Pickup and Van, readjust preload.
4. If preload is within specifications, check meshload. Measure highest torque required to rotate steering wheel back and forth approximately 90° either way across center position.
5. Meshload must be 4-10 INCH lbs. (4.5-11.3 N.m) on Bronco II and Ranger or 9-14 INCH lbs. (10.2-15.8 N.m) on Pickup and Van. Meshload must also be at least 2 INCH lbs. (2.3 N.m) over preload. Meshload can be adjusted in vehicle.

WORM BEARING PRELOAD & MESHLOAD

1. Remove steering gear from vehicle. See «REMOVAL & INSTALLATION»(/ford/bronco-ii/i-1984-1990/remont/steering-gear/#steering-gear-manual) . Tighten sector cover bolts to 40 ft. lbs. (53 N.m). Loosen preload adjuster lock nut and screw.
2. Tighten worm bearing adjuster until all end play has been removed. Lubricate worm shaft seal with a drop of A/T fluid and power steering fluid. Turn worm shaft carefully to right stop.
3. Using an INCH lb. torque wrench, measure torque required to rotate worm shaft to left, in a constant motion, for approximately 1 1/2 turns.
4. Turn adjuster nut to obtain a preload of 5-6 INCH lbs. (5.6-6.8 N.m) on Bronco II and Ranger or 7-9 INCH lbs. (7.9-10.2 N.m) on Pickup and Van. Tighten adjuster nut to 187 ft. lbs. (253 N.m).
5. Rotate worm shaft from stop to stop, counting total number of turns. Then turn back halfway, placing gear on center. Will be 7 turns on Pickup and Van and 6 turns on Bronco II and Ranger. Using an INCH lb. torque wrench, measure highest reading while worm shaft is turned approximately 90° either way across center.
6. If highest reading (meshload) is not within 9-11 INCH lbs. (10.2-12.4 N.m) on Bronco II and Ranger or 12-14 INCH lbs. (13.6-15.8 N.m) on Pickup and Van, turn sector shaft adjusting screw as required.
7. Meshload must be at least 4 INCH lbs. (4.5 N.m) over preload. Hold sector shaft adjusting screw and torque locknut to 25 ft. lbs. (34 N.m).

TROUBLE SHOOTING

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

Removal

1. Disengage flex coupling shield from steering gear input shield and slide it up intermediate shaft. Remove flex coupling-to-steering gear bolt.
2. Remove steering gear input shaft shield. Remove pitman arm nut and washer. Remove pitman arm using Pitman Arm Puller (T64P-3590-F). Remove steering gear-to-frame attaching bolts and remove gear.
3. On Pickup and Van, remove coupling-to-gear attaching bolt from lower half of flex coupling. Remove coupling from steering gear assembly.

Installation

1. Center worm shaft in steering gear. Ensure that flat on gear input shaft is facing straight up and aligns with flat on flex coupling. Install steering gear to side rail and tighten bolts to 70 ft. lbs. (95 N.m) on Van, 54-66 ft. lbs. (74-89 N.m) on Pickup and 66 ft. lbs. (88 N.m) on Bronco II and Ranger.
2. Align 2 blocked teeth on pitman arm with 4 missing teeth on sector shaft. Install nut and tighten to 230 ft. lbs. (312 N.m). Install flex coupling-to-steering gear bolt. Snap flex coupling shield to steering gear input shaft shield.

DISASSEMBLY

1. Place steering gear in a vise, clamping onto one mounting tab or a holding fixture. Worm shaft should be in a horizontal position, and centered in steering box.
2. Remove sector shaft cover bolts. Lift sector shaft and cover out of gear. Remove cover from shaft by turning screw clockwise. Keep shim with screw.
3. Loosen lock nut on worm shaft adjuster with Lock Nut Wrench (T83T-3504-AH), and remove adjuster plug and worm shaft thrust bearing. Pull worm shaft and ball nut assembly from housing. Remove upper thrust bearing.
4. DO NOT allow ball nut to run down to either end of worm shaft as ball guide ends may be damaged. Pry out and discard both sector shaft and worm shaft seals. NOTE: Individual parts are not available for service. If worm cannot rotate freely in ball nut, replace entire assembly.
5. Remove worm shaft adjuster nut bearing cup with a Slide Hammer and Puller Attachment (T50T-100-A and T58T-101-A). Remove bearing cup from housing using a bearing driver or socket.
6. Sector shaft cover bushing is not serviceable. Entire sector cover assembly is serviced as a unit. Sector shaft needle bearing is serviced only as a unit with housing. DO NOT attempt to remove sector needle assembly.

Exploded View of Steering Gear. Scheme 2

CLEANING & INSPECTION

1. Wash parts with clean solvent and blow dry with air. Inspect bearings and races for signs of wear. Any parts that show signs of wear should be replaced.
2. Inspect sector shaft fit at side cover bushing assembly. If bushing is worn, a new side cover and bushing assembly should be installed. Check ball nut and worm shaft assembly for wear and straightness.
3. Inspect worm shaft and ball nut for tightness or binding by turning worm shaft in ball nut. If ball nut and worm shaft is defective, replace as an assembly.
4. Inspect steering gear housing for cracks or damage. Inspect needle bearing inside housing for defects. Replace housing if any defects are found. Inspect sector gear teeth for chipping, excessive wear and surface breakdown.
5. Check clearance between sector adjusting screw head and bottom of sector shaft "T" slot. If clearance is more than.004" (.10 mm), replace shim to obtain desired clearance.
6. Steering gear lash adjuster shims are available in.078" 1.95 mm),.080" (2.00 mm),.082" (2.05 mm),.084" (2.10 mm) and 086" (2.15 mm). Hold sector adjuster screw and turn sector shaft.
7. Sector must turn freely. If sector does not turn freely, increase "T" slot clearance by replacing shims. (Scheme 3)

Checking Sector Shaft "T" Slot Clearance. Clearance may be adjusted by replacing shims. Scheme 3

Scheme 4

1. All seals, bushings, and worm shaft bearing cups should be installed. Clamp housing in a vise with worm shaft bore horizontal and sector cover opening up.
2. Apply steering gear grease to worm shaft bearings, sector shaft needle bearings and sector cover bushing. Slip thrust bearing over worm shaft splined end and position correctly. (Scheme 4)
3. Install worm shaft nut, splined end first, into housing. (Scheme 4) Place remaining worm shaft bearing into adjuster plug bearing cup. Lubricate bearing before assembly. Install adjuster plug and lock nut into housing.
4. Screw adjuster nut down until nearly all end play has been removed. Lubricate steering gear by rotating worm shaft until ball nut is end of its travel.
5. Pack as much grease as possible into steering gear housing without losing it out sector shaft opening. Rotate ball nut to other end of its travel and pack more grease into housing.
6. Rotate ball nut until it is in center of its travel. Insert sector shaft assembly, containing adjusting screw and shim into housing. Center tooth of sector gear must engage center rack tooth space in ball nut. (Scheme 4): Installing Worm Shaft Thrust Bearing
7. Pack housing with grease. Apply a thin bead of sealant to sector shaft cover and install on housing. Engage sector adjuster screw with tapped hole in center of sector cover by turning screw counterclockwise.
8. Turn screw until sector cover is flush with housing. Install sector cover bolts but do not tighten unless there is a lash between sector shaft and worm shaft.
9. Tighten sector cover bolts to 40 ft. lbs. (54 N.m). Adjust steering gear preload and meshload. See «ADJUSTMENTS»(/ford/bronco-ii/i-1984-1990/remont/steering-gear/#steering-gear-manual).

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• REMOVAL & INSTALLATION