SECTION 8-A 1956 BUICK MANUAL STEERING GEAR AND LINKAGE
8-1 DESCRIPTION OF CHANGES IN 1956 BUICK MANUAL STEERING GEAR
1956 Buick Steering Gear Assembly
The manual steering gear for 1956 will have a ratio increase from 23.6 to 25.8:1 with a resultant decrease in steering effort. The manual steering gear will be standard equipment on the Series 40 and 60 only.
The steering gear will be trunnion mounted. A new worm thrust bearing adjustment reduces the possibility of misalignment due to tolerance stack up, and gives a smoother feeling gear. In order to simplify adjustment, an external hex replaces the slot on the bearing adjuster. The manual steering gear is serviced in the same manner as in 1955. See Figure 8-1.
Manual Steering Linkage
The manual steering linkage is the same as used in 1955 except for the pitman arm which has the block tooth location revised to fit a 25.8 to 1 ratio gear. The tie rods have a revised offset which was required by the seven degree kingpin angle steering knuckles.
8-2 REMOVAL AND INSTALLATION OF MANUAL STEERING GEAR
Removal of 1956 Buick Steering Gear
The removal procedures of the 1956 manual steering gear are the same as described in Paragraph 8-6 of the 1955 Buick Shop Manual with the exception of Step 10. Step 10 will be replaced with the following procedure:
- Remove the brake pedal socket screws; then remove the pedal sockets and retainer.
- Remove the pivot bolt, nut, bolt and then the pedal. (For cars equipped with synchromesh transmissions, remove clutch pedal by same procedure.)
- Remove dash insulator screws, then remove dash insulator.
- Remove accelerator pedal and roll back floor mat.
- Support master or power cylinder with wooden block, then remove master or power cylinder to toe pan attaching bolts and toe pan.
Installation of 1956 Buick Steering Gear Assembly
Install the gear assembly by reversing the procedure for removal.
NOTE: When replacing the steering column bracket cap, be sure that the nylon pin in the cap enters the slot in column jacket.
NOTE: The height of the steering wheel may be adjusted up or down about 1% inches (total range) by means of elongated vertical slots under the instrument panel at the steering column upper bracket. On manual gears, the toe-in adjustment should be checked when the steering wheel height is changed.
SECTION 8-B 1956 BUICK POWER STEERING GEAR AND PUMP
8-8 1956 BUICK POWER STEERING GEAR AND PUMP SPECIFICATIONS
- Tightening Specifications
8-9 DESCRIPTION QF POWER STEERING GEAR AND PUMP
Changes in power steering for 1956 consist of a modified power steering pump and an entirely new light weight power steering gear of the in-line type. Buick Power Steering, standard equipment on Series 50-70 and available as optional equipment on all other models, consists of an in-line power steering gear with the worm and ball nut, power piston and rack, and the power cylinder all on a single center line. The valve is mounted directly on the gear housing, thereby eliminating all external lines and hoses except the pressure and return lines between the valve and a high pressure pump. See Figure 8-10.
The engine drives the oil pump which furnishes hydraulic pressure. When the engine is not running, or when any part of the power mechanism is inoperative, steering is entirely manual and requires only slightly more effort at the steering wheel than the manual gear used as standard equipment.
With the engine running, steering is entirely manual under conditions which require an effort of less than two and three-quarters (2 3/4) pounds at the steering wheel rim. When a greater effort is required, the power mechanism operates to ASSIST in turning the front wheels. The effort then required at steering wheel rim is limited to a maximum of approximately six pounds for normal steering and parking conditions, compared to possibly fifty pounds with the standard manual gear. If some abnormal condition requires more work than the power mechanism can do, the driver must assist with increased effort at the steering wheel.
The driver’s effort on the steering wheel is always proportional to the force necessary to turn the front wheels. When the effort on the wheel drops to less than two and three-quarters (2 3/4) pounds as the turn is completed, power assistance ceases. When the wheel is released to recover from a turn, the front wheels may return to the straight-ahead position in the usual manner without assistance or interference from the power mechanism. Through this conventional steering action the driver always has the “feel” of steering.
It should be noted that power steering always follows the manual steering action. No steering action is obtained except through the manual guidance of the driver.
The hydraulic units and steering gear housing are filled with the same oil as specified for Dynaflow transmissions.
Power Steering Gear Assembly
The power steering gear assembly is the recirculating ball nut and worm type, having a ratio of 17.5 to 1.
The upper end of the pitman shaft has a gear section meshing with a rack which is a part of the power piston. This rack-piston slides in the gear housing which is cylindrical. The rack-piston assembly consists of power piston and rack with two piston rings and also a ball nut locked rigidly in place with a retaining screw. See figure 8-11.
A worm shaft turns in the ball nut using selectively fitted steel balls as a rolling thread. The ball groove is shallower in the center of the worm so that when the proper size balls are used, there is a slight worm to ball nut pre-load in the straight ahead position.
Worm shaft radial loads are transmitted to the gear housing through a needle bearing at the upper end and through the rack-piston at the lower end. Worm shaft end thrust is caused by the tendency of the worm to thread itself into or out of the ball nut as the wheel is turned right or left. This end thrust is absorbed entirely by a pre-load thrust bearing. Any end thrust causes a movement of the thrust bearing center race which is held in position by centering springs; the more the end thrust, the more the movement of the center race up to a point where it bottoms in its housing. This movement of the center race is transmitted to the control valve through the valve actuating lever.
The upper steering shaft is a separate shaft supported in the steering column jacket. Its upper end is supported by a ball bearing; its lower end by an adapter and ball bearing assembly.
The upper steering shaft is connected to the power steering gear worm shaft through a flexible coupling. This flexible coupling helps absorb minor shocks and vibrations, dampens out hydraulic noises and gear rattle, and also allows slight variations in alignment between the power gear assembly and the steering column jacket assembly.
The hydraulic valve controls the flow of oil from the pump to the proper side of the power rack-piston when power assistance is required and cuts off this flow when power assistance is not required. It also regulates the effort at steering wheel within the normal range of two and three-quarters (2 3/4) to six (6) pounds so that this effort is proportional to the force necessary to turn the front wheels, thereby providing the “feel” of steering previously mentioned. See Figure 8-11.
The valve spool is held in a neutral position by means of a valve centering spring located in the valve reaction chamber plus the thrust bearing centering springs. The hydraulic valve contains a second spool, located in the center of the valve spool. This second spool establishes the maximum pressure that may be produced in the reaction chamber and thereby decreases the hand-wheel effort when parking.
During a left turn, the thrust bearing is moved up and in a right turn the thrust bearing is moved down. This in turn moves the actuating lever up or down which is connected to the link on the valve spool. The movement of the actuating lever moves the control valve spool which directs the oil flow through the control valve to the cylinder.
The Saginaw oil pump, which is mounted on the engine in position to be driven by a belt from the crankshaft balancer, converts some engine power into oil pressure which is used by the power cylinder and rack-piston to rotate the pitman shaft.
The pump houses a slotted driving hub or rotor in which ten vanes slide radially outward to contact the hardened and ground inside surface of a ring. As the shaft and rotor rotates, centrifugal force and fluid pressure against the inner ends cause the vanes to follow the cam contour of the ring, which is so shaped that two opposing pumping chambers are formed. See Figure 8-41. In each pumping chamber, the increasing and decreasing pockets formed between the rotor, vanes, and ring propel the oil from the reservoir into a discharge cavity in the pump cover.
Oil flows from the discharge cavity into the exit port in pump cover through a restricted passage (.116″ dia.); therefore, pressure in the discharge cavity is always greater than that in the exit port. A control valve assembly regulates the opening of another passage through which oil may be bypassed back to the reservoir. See Figure 8-12. The valve assembly includes a flow valve and a pressure relief valve.
When the pump is running without demand for steering pressure, pressure in the discharge cavity is high enough to push the flow control valve open against a spring load of approximately ten pounds. A small orifice leads oil from the exit port into the spring chamber and this pressure tends to close the valve. Since pressure in the discharge cavity is always greater than in the exit port the valve is not closed, and the flow valve action depends on the spring load and the difference in pressure on the inner and outer ends of the valve.
When power steering is demanded and the steering gear control valve restricts free circulation of oil as described later (par. 8-10), the pump pressure builds up rapidly. When pump output pressure reaches a predetermined maximum the increased pressure in the flow valve spring chamber forces the pressure relief valve open, and oil escapes from the spring chamber into the by-pass passage. As oil pressure is relieved in the spring chamber, the high pressure in the pump discharge cavity overcomes the spring load to completely open the flow valve. See Figure 8-12. Oil is dumped into the by-pass passage until the line pressure opposing the pump drops below the relief valve setting, permitting this valve to close. The flow valve then resumes normal operation.
The flow valve starts to open at 300-400 RPM of pump and is functioning when pump idles at 465 RPM (400 RPM of engine). The minimum flow the pump must produce is 1.5 gal. per minute at 465 RPM against a pressure of 700 psi. The flow valve permits a maximum flow of 2.1 gal. per minute at 1500 RPM against a pressure of 50 psi. The pressure relief valve is set for 975-1075 psi.
Reservoir and Hoses
The reservoir is mounted on top of the oil pump and provides a reserve supply of oil to assure complete filling of the hydraulic system. The reservoir is vented at the cover bolt by bleed grooves in the washer which permit escape of any air that may be introduced into the system during assembly of the various units and maintains atmospheric pressure in the reservoir.
In order to remove any foreign matter which may have entered the oil while it passed through the system, a wire mesh filter has been installed in the reservoir through which all the return oil passes prior to its mixing with the oil contained in the reservoir.
A pressure line hose and a return line hose connect the oil pump to the hydraulic valve in the steering gear. See Figure 8-10. The pressure line hose is reduced in size at the valve end to provide a dampening effect on any turbulence in the oil stream.
8-10 OPERATION OF HYDRAULIC POWER MECHANISM
When the steering wheel is turned, the ball nut must move axially along the worm shaft in order to rotate the pitman shaft and thereby turn the front wheels through the connecting linkage. Movement of the ball nut is opposed by the force necessary to turn the front wheels, consequently, the worm shaft tends to move endwise through the ball nut. The ball nut and worm shaft act like a screw jack to thrust a load against the worm thrust bearing, tending to move the bearing.
Movement of the thrust bearing (and worm shaft) is opposed by thrust bearing springs and valve centering springs in the hydraulic valve, therefore, the thrust load must exceed the total preload of the springs before the worm shaft can actually move endwise. Consequently, the worm shaft will move endwise only when the force necessary to turn the front wheels requires an effort of more than two and three-quarters (2 3/4) pounds at the steering wheel.
Figure 8-13 shows the valve in the neutral or straight-ahead position and by following the arrows, which indicate oil flow, it is noted that the oil flows from the pump, through the open center valve and back to the pump reservoir without ever approaching the power cylinder. All passages are open in the neutral position and the valve remains in this position at all times except when effort applied to steering wheel is more than two and three quarters (2 3/4) pounds. The valve’s “open center” feature reduces losses to a minimum. It should be understood that the power cylinder is full of oil at all times, although in the straight-ahead position the pressure on both sides of the piston is equal and very low (approximately 30 to 50 psi). This oil acts as a cushion that absorbs road shocks so they are not transferred to the steering wheel, thus giving safer and more effortless driving. In addition, this oil lubricates all internal components of the gear making it unnecessary to grease the gear at any time.
Figure 8-14 illustrates the function of the gear when the steering wheel is turned to the right. Due to the turning resistance, the steering worm tends to screw down into the ball nut; therefore, as the driver applies right turn effort to the steering wheel, the worm is allowed to move downward a slight amount. As the worm moves downward it also moves the thrust bearing downward, which, in turn, causes the valve actuating lever to move the valve spool upward. As this spool moves, the relationship between the grooves in the spool and the grooves in the valve housing is changed so that the lower spool groove is no longer as fully open to return but is opened wider to the pressure side of the pump, and the upper spool groove is opened more fully to return but less fully to the pressure side of the pump. This causes the oil to flow into the lower half of the pressure cylinder and force the piston upward toward the driver. As the piston moves upward, it moves the power rack with it, which in turn, applies turning effort to the pitman shaft.
The oil in the upper end of the cylinder is simultaneously forced out through the valve and back to the pump reservoir. The higher the turning resistance, the more the valve spool is displaced, and the higher the oil pressure on the lower end of the piston.
The instant the driver stops applying steering effort to the wheel, the valve spool is forced back into its neutral position by three forces; the centering spring in the valve reaction chamber, the centering springs on the thrust bearing, and the hydraulic reaction in the valve reaction chamber. When this happens, the oil pressure is again equal on both sides of the piston and the steering geometry of the car causes the wheels to return to the straight-ahead position.
Simultaneously with the turn explained above, oil pressure increases in the valve reaction chamber. This is the feature in the valve that gives the driver the “feel of the road” at all times. As the driver turns to the right and oil pressure builds up in the cylinder, equal oil pressure builds up in this reaction chamber. The more effort required to turn the front wheels, the higher the pressure builds in the reaction chamber. Since it is this pressure that tends to recenter the valve, the driver has to apply more effort to the steering wheel as the pressure in this chamber increases. To summarize, the more the turning resistance, the greater the pressure in this chamber, and therefore, the more effort the driver must apply to the steering wheel to turn the car. This proportional effort provides the steering “feel.”
The amount of pressure that can be built in the reaction chamber is limited to 250 psi by the reaction control spool. As the pressure in the reaction chamber increases, the reaction control spool is forced downward, by this pressure, against the force of the reaction control spool spring until it blocks the oil passage between the reaction chamber and the pump.
This passage is blocked at 250 psi in the reaction chamber. If, because of internal leakage past the reaction control spool, the pressure in the reaction chamber should tend to go higher than 250 psi, it would force the reaction control spool slightly further down. When this occurs, the top end of the reaction control spool moves past an oil passage to the relief side of the pump and relieves some of this reaction chamber pressure. This feature insures against ever building excessive pressures in this chamber.
With 250 psi maximum in the reaction chamber, it only requires about six pounds effort on the steering wheel to turn the car when parking, the most difficult of turning conditions.
Power steering linkage has been changed by the elimination of the anti-wheel kick springs at the pitman arm ball.
The pitman arm will have a larger internal spline than the 1956 manual steering pitman arm in order to fit the 1.25 inch O.D. pitman shaft used with the 1956 steering gear. The tie rods will be the same as those used in the manual steering linkage to fit the seven degree kingpin angle steering knuckles.
8-11 TROUBLE DIAGNOSIS-POWER STEERING GEAR AND PUMP
This paragraph will cover only those causes of trouble which may be due to the hydraulic power mechanism. Causes which are due to the steering linkage, and front suspension are the same as described for the standard steering gear in paragraph 8-3.
Before assuming that the hydraulic power mechanism is at fault, make certain that the mechanical components are in proper condition.
Hard Steering While Driving
- Steering adjustment tight. Check adjustment by dropping pitman arm from gear or disconnect linkage from pitman arm ball.
- Insufficient pressure build up in power cylinder due to leak or faulty valve. Replace defective parts.
Poor Return of Steering Gear to Center
- Tight sector to rack-piston adjustment. Adjust in car to specification.
- Sticky or faulty control valve. Change valve assembly.
- Control valve improperly positioned on steering gear. Loosen control valve screws, allow valve to center itself and retighten screws.
- Ball nut and worm pre-load too tight. Remove gear and replace balls as required.
- Worm thrust bearing adjustment too tight. Remove gear and adjust to specification.
- Sticky valve actuating lever. Free up lever.
Momentary Increase in Effort When Turning Wheel Fast to the Right
- Air in system. Bleed gear.
External Oil Leaks (Wipe gear thoroughly and make sure source of leakage Is determined)
- Loose hose connection or damaged hose. Tighten or replace.
- Housing end cover seal, O-ring seal, adapter O-ring seal, or side cover O-ring seal. Replace seal.
- Linkage cover O-ring seals, valve to gear housing O-ring seals. Replace seal.
- Pitman shaft seal and valve end plug O-ring seal. Replace seal.
- Pitman shaft over center adjustment screw. Replace screw in cover.
Gear Noise (rattle. or chuck)
- Loose over center adjustment.
Gear Noise (hissing sound}
- If objectionable, change valve.
Excessive Wheel Kickback or Loose Steering
- Lash in valve linkage. Replace affected parts.
- Air in system. Add oil to pump reservoir and bleed.
- Excessive lash between pitman shaft sector and rack-piston. Adjust to specification.
- Loose worm thrust bearing adjustment. Remove gear and adjust to specification.
- No preload on ball nut and worm assembly. Replace balls as required.
- Ball nut retaining screw loose in piston. Replace screw and restake securely.
Steering Wheel Surges or Jerks When Turning With Engine Running
- Loose pump belt. Adjust to specification.
Hard Steering When Parking
- Loose pump belt. Adjust to specification.
- Low oil level in reservoir. Fill to proper level. If excessively low, check all lines and joints for evidence of external leakage.
- Steering gear adjustments tight. Adjust to specifications.
- Insufficient oil pressure. If all the above checks do not reveal the cause of hard steering, make the following test of oil pressure:
- Disconnect the pressure line at oil pump, attach gauge to pump, connect the hose to end of gauge where the valve is located.
- With engine at warm idle and gauge valve open, note the oil pressure on the gauge while turning steering wheel from one extreme position to the other. Especially note the maximum pressure which can be built up with the wheel held in either right or left extreme position.
CAUTION: Do not hold wheel in extreme position for an extended period of time because it will drastically increase the oil temperature and will cause undue wear on the oil pump.
- With oil temperature between 150°F and 170°F, as measured with a thermometer in the reservoir, the minimum oil pressure at idle should be at least 875 psi for satisfactory power steering operation.
- If the maximum oil pressure is less than 875 psi, it indicates trouble in the pump, oil hoses, steering gear, or a combination of these parts. To eliminate the hoses and gear, close the gauge valve and quickly test pressure of the pump only, with the engine at warm idle, then open the valve to avoid increasing oil temperature. A minimum pressure of 875 psi should be present with valve closed.
- Low oil pressure due to steering gear.
- Leakage at adapter seal, adapter O-ring, worm seal, valve-to-housing O-ring, side cover O-ring, pitman shaft seal. Remove gear from car for replacement of seals.
- Pressure loss in cylinder due to worn piston rings or scored housing bore. Remove gear from car for disassembly and inspection of seals, rings and housing bore.
- Pressure loss in control valve due to annulus O-rings or leakage between spool and body. Replace annulus O-rings or valve assembly as necessary.
- Hydraulic reaction relief spool in center of valve spool not functioning. Replace valve assembly.
8-12 REMOVAL AND INSTALLATION AND BLEEDING OF POWER STEERING GEAR
Removal of Power Steering Gear Assembly
- Place fender cover over left front fender.
- Disconnect the pressure and return line hoses at the steering gear and elevate ends of the hoses higher than pump to prevent oil from draining out of pump.
- Disconnect the flexible coupling by removing two bolts which attach flexible coupling to steering shaft.
- Jack up car and remove the pitman shaft nut, then remove the pitman arm.
- Remove the four steering gear to frame bolts at outside of left frame rail.
- Remove steering gear.
Installation of Steering Gear Assembly
- Install the gear assembly by reversing the procedure for removal.
- Check toe-in after installation is completed.
Bleeding of Power Steering Gear Assembly
- Fill pump reservoir to proper level.
- With engine running, loosen bleed screw in steering gear side cover, to allow air to escape.
- Tighten bleed screw and check oil level. NOTE: Bleeding of the system will be necessary if air becomes trapped in system due to low oil level in the pump reservoir.
Removal and Installation of Oil Pump
- When removing the pump, use shipping plugs and caps to cover the hose connectors and unions on pump and plug open ends of the pressure and return line hose to avoid entrance of dirt.
- When pump is installed on mounting bracket, adjust drive belt tension by using a torque wrench applied to the pulley nut. With a new belt, the tension should be set so that the pulley will slip in belt when 40-45 ft. lbs. torque is applied to pulley nut. With a used belt the torque should be 30-35 ft. lbs.
- Fill the reservoir to proper level with specified Dynaflow oil.
NOTE: The height of the steering wheel may be adjusted up or down about 1% inches total range by means of elongated vertical slots under the instrument panel at the steering column upper bracket. It is not necessary to check toe-in adjustment unless the position of the steering gear has been changed. Because power steering gears have a flexible coupling in the shaft, the adjustment may be made without changing the location of the gear. The flexible coupling should be checked after the adjustment, however, to make sure it doesn’t bind or have metal to metal contact between the upper and lower parts. If it is necessary to move the gear to realign the coupling, the toe-in must be checked.
8-13 ADJUSTMENT OF PITMAN SHAFT
Adjustment of Pitman Shaft with Power Steering Gear in Car
- Disconnect pitman arm from intermediate tie rod and check tightness of pitman arm nut with an 18″ wrench.
NOTE: Never attempt to adjust steering gear with pitman arm connected to intermediate rod.
- Turn steering wheel slowly through its full travel to check for binding, tight spots or uneven action.
- Turn steering wheel to extreme right or left position. Apply Scale J-544-A to a spoke at rim of wheel and, while pulling scale at 90 degrees to spoke, check the pull required to turn the wheel steadily in the range where lash normally exists between ball nut and pitman shaft sector. The lash range exists for one eighth turn of steering wheel from either extreme position.
- The reading on the scale should be between 1/4 and 1/2 pound, which would indicate normal loading or drag at the thrust bearing.
- Loosen pitman shaft adjusting screw lock nut and turn adjusting screw counter clockwise a few turns.
- Check the pull required to turn the wheel through the “high-point” or no lash range. The reading should be 1/4 to 3/4 lb. higher than previous reading, which would indicate normal ball nut preload.
- If readings are not within specifications, remove power steering gear and recheck adjustment on bench as outlined in paragraph 13 (b).
- If readings are within specifications, turn pitman shaft adjusting screw clockwise as required to obtain a scale reading 1/2 to 1 pound higher than was obtained in step 6. This reading is taken when pulling wheel through “high point” with lock nut tight. Total reading should be between 1 1/4, to 1 3/4 lbs.
- Connect intermediate rod to pitman arm and adjust end plug as specified.
Adjustment of Pitman Shaft with Power Steering Gear Removed
Adjustment of pitman shaft can also be made on bench with power steering gear completely assembled.
- Place power steering gear assembly in vise with wormshaft up. See Figure 8-16. Install Over Center Adjuster J-6281 on flexible coupling.
This reading is taken when pulling the Over Center Adjuster through “high-point” range with lock nut tight. Total reading should be 1 1/4 to 1 3/4 lbs.
8-14 DISASSEMBLY, INSPECTION, ASSEMBLY OF CONTROL VALVE ASSEMBLY
Removal of Control Valve Assembly
- Thoroughly clean exterior of gear assembly with a suitable solvent and drain the unit by placing control valve down and turning the worm shaft through its entire range two or three times.
- Remove the control valve retaining bolts and lift control valve and linkage cover off the gear housing. Then pull the linkage cover out of the valve body. See Figure 8-17.
Disassembly of Control Valve Assembly
- Remove annulus retaining snap ring using No. 1 Truarc Ring Pliers J 5403 and annulus retaining washer. Then slide spool assembly out of the valve body. Care should be taken to see that neither the spool assembly or the valve body are scratched or dropped. See Figure 8-18.
Inspection of Control Valve Assembly
- Inspect inside of valve body and both spools for scores, nicks, or burred edges. If either the valve body or one of the spools is damaged, a complete control valve assembly must be replaced as the valve body and spools are selective fits and therefore are available only as an assembly.
- Inspect the hose connectors. If badly brinelled or scored, replacement will be necessary. To remove the connectors, tap threads in the hole using a 5/16-18 tap in the large connector and a No. 12-24 tap in the small connector. Pull the connector by using a bolt threaded into the tapped hole and a flat washer and nut as an extractor. Wash and blow the valve body out thoroughly to remove any tapping chips. To replace the connector, use Replacer J 6217 to drive the connector in place.
Reassembly of Control Valve Assembly
- Thoroughly clean all the parts and lubricate the internal parts with Dynaflow oil. Then clamp spool in vise in same manner as in disassembly, and install reaction control spring and spool with narrow land next to spring. Assemble spring thrust washer and valve centering spring on the spool. Lubricate new annulus O-ring seals with Dynaflow oil and install on annulus. Assemble annulus on spool with narrow land of annulus toward spring.
- Hold annulus down on spool to compress the spring. Then assemble link and tighten to 8-10 ft. lbs. using Remover and Replacer J 6224. See Figure 8-20.
Remove the spool assembly from vise. Carefully insert the spool assembly into the valve body. The spool and valve body are selective fits and have very little clearance. Only if properly started can the spool be assembled. DO NOT ATTEMPT TO FORCE THE SPOOL INTO THE VALVE BODY.
Installation of Control Valve Assembly
- Lubricate new linkage cover O-ring seal and install on linkage cover. Assemble linkage cover to control valve. Position valve link so that slot is perpendicular with the bottom of valve.
- Install the two small new O-ring seals on gear housing and new O-ring seal on end cover. Position control valve and linkage cover over gear housing and end cover. Start actuator lever into the link slot and then push down on the linkage cover until the valve is seated on the housing.
- Install control valve retaining bolts and tighten to 15-20 ft. lbs. Tighten the bolt on lower end of control valve first. BE SURE NOT TO FORCE THE VALVE IN EITHER DIRECTION WHILE TIGHTENING BOLTS AS THIS WILL CAUSE MALFUNCTIONING OF THE VALVE.
8-15 DISASSEMBLY, INSPECTION, ASSEMBLY OF PITMAN SHAFT ASSEMBLY
Removal of Pitman Shaft Assembly
- Remove control valve assembly as outlined in Paragraph 8-14 (a).
- Remove side cover retaining bolts and rotate cover one-half turn. Align pitman gear with opening in gear housing by turning worm shaft. Tap the end of pitman shaft with a soft mallet and remove pitman shaft from housing.
Disassembly of Pitman Shaft Assembly
- Hold pitman shaft adjusting screw with a screw driver and remove adjusting screw locknut. Turn the screw out of cover and remove cover. Then slip the adjusting screw and ‘ shim out of the slot in the pitman shaft. Discard the adjusting screw. A nylon pin in the adjusting screw prevents any loss of fluid past the treads. Whenever the adjusting screw is removed this pin is damaged and a new adjusting screw should be installed.
- Remove the pitman shaft seal retaining snap ring from end of housing using No. 3 Truarc Pliers J 4245. Remove seal back-up washers and leather dust seal. To remove shaft oil seal, tap an offset screw driver in between seal and shoulder in gear housing, then pry seal out of housing being careful not to damage the seal bore in housing.
Inspection of Pitman Shaft Assembly
- Inspect pitman shaft bearing surface in side _ cover for excessive wear or scoring. If worn or scored replace side cover.
- Check pitman shaft sector teeth and bearing surfaces. If worn, pitted, or scored, replace shaft. Then check the pitman shaft bushing in housing for wear. If worn remove old bushings and install new bushings using Remover and Replacer J 6220.
Reassembly of Pitman Shaft Assembly
- Check the end play of new adjusting screw in the slot of pitman shaft by inserting a feeler gauge between the head of the screw and bottom of slot. End play should not exceed .002″. If end play exceeds .002″ install proper shim. The shims are available in four different thicknesses: .063″, .065″, .067″ and .069″. See Figure 8-21.
Installation of Pitman Shaft Assembly
- Turn worm shaft as necessary until the center groove of the rack-piston is aligned with center of pitman shaft bushing. Install pitman shaft so that the center tooth in the sector meshes with the center groove of rack-piston. Make sure that new side cover O-ring is in place, then push the side cover down on gear housing.
- Install and tighten the four 3/8″ side cover bolts to 25-30 ft. lbs. Install and tighten the 5/16” side cover bolt to 15-20 ft. lbs. Then install adjusting screw lock nut.
- To prevent damage to pitman shaft oil seal, fully cover pitman shaft splines with tape.
- Install pitman shaft oil seal with lips inward using Installer J 6219. Install the one seal back-up washer with small J.D. next to seal. Then install leather dust seal with lip outward and other seal back-up washer. Install pitman shaft seal retaining snap ring with beveled side out using No.3 Truarc Pliers J 4245. Make certain that retaining ring is properly seated. See Figure 8-22.
8-16 DISASSEMBLY, INSPECTION, ASSEMBLY OF RACK-PISTON AND WORM ASSEMBLY
Removal of Rack-Piston and Worm Assembly
- Remove control valve assembly as outlined in Paragraph 8-14 (a) and pitman shaft as outlined in Paragraph 8-15 (a).
- Remove flexible coupling and mark coupling flange and worm shaft before disassembly. Support coupling flange and remove coupling flange and felt washer from worm shaft by driving pin out with punch. See Figure 8-23.
Disassembly of Rack-Piston and Worm Assembly
- Remove piston rings from rack-piston. Remove ball nut retaining screw using Screw Adapter J 6223 and slide the ball nut and worm assembly out of rack-piston with ball nut retaining screw hole down to prevent ball return guides from falling out and losing balls. See Figure 8-25.
Inspection of Rack-Piston and Worm Assembly
- Inspect the worm and ball nut grooves and all the balls for wear or scoring. If either the worm or ball nut needs replacing, both must be replaced as a matched assembly.
- Inspect ball return guides, making sure that the ends where the balls enter and leave the guides are not damaged.
- Inspect the rack-piston teeth for pitting, wear, and scoring. Inspect all bearing surfaces on rack-piston for scoring. Do not remove rack-piston end plug unless it is loose. To replace plug, drive old plug out from inside rack-piston, press new plug in flush with end of rack-piston and stake securely in four places.
- Inspect housing bore. If badly scored or worn, replace housing. Inspect housing end plug for leakage. Unless there is visual evidence of leakage, do not remove end plug. To remove end plug, the staked portion must be either pushed up or cut off so that the plug may be driven into the housing without scoring the sealing diameter. To replace the end plug, lubricate a new plug O-ring seal and install on a new end plug. Install end plug in housing from the inside and stake plug securely in four places. Inspect the pitman shaft bushings and if badly worn, replace as outlined in Paragraph 8-15 (c).
- Inspect the thrust bearing centering springs. If any of the four springs riveted to the thrust bearing are broken, the thrust bearing assembly must be replaced. If any of the four loose springs are broken, replace all four.
- Check for roughness by holding the worm stationary and rotating the center race. If the bearing is rough, replace thrust bearing assembly. Check the thrust bearing preload. This should be between 3/4 and 3 lbs. measured at the outer edge of the center bearing. To measure bearing preload, clamp the worm in a vise using soft jaws. Fasten a cord to one of the riveted centering springs and wind it around the center race. Attach the other end of the cord to Spring Scale -J-544-A. Then slowly pull the other end of the scale and check the reading. If the, preload is not within the limits, push the staked portion of the thrust bearing nut up out of the thread groove, being careful not to damage the thread, and remove the nut and discard. Use a new nut and adjust as necessary to obtain proper preload. After the proper preload has been obtained recheck bearing for roughness and stake the nut being careful not to move the nut when staking. Recheck the preload after staking. See Figure 8-27.
Reassembly of Rack-Piston and Worm Assembly
- Thoroughly clean, oil the parts, and lubricate the internal parts with Dynaflow oil. Use only new seals and gaskets during assembly.
- Lubricate O-ring and install on adapter. Lubricate and install adapter oil seal with black rubber side out, then install seal back-up washer and retaining ring. Assemble adapter to worm being careful not to damage the seal when passing over the worm grooves. Slide the ball nut with the chamfered edge away from the adapter over the worm up to the adapter. See Figure 8-29.
Press in new end cover oil seal using Seal Installer J 5188 with lips toward tool. Lubricate seal with Dynaflow oil and install new O-ring seals on end cover. Lubricate needle bearing with chassis lubricant.
- Install Seal Protector J 6222 over worm serrations to prevent damage of end cover seal. See Figure 8-37.
Assemble end cover over worm and adapter making certain that adapter pin enters pilot hole in end cover. Align end cover holes with housing holes and install retaining bolts. Tighten bolts evenly to 25 to 30 ft. lbs.
8-17 DISASSEMBLY, INSPECTION, ASSEMBLY OF SAGINAW OIL PUMP
Disassembly of Saginaw Oil Pump
- Use shipping caps to cover the hose unions on pump to exclude dirt, then thoroughly clean exterior of pump.
- Remove reservoir cover, drain out all oil and remove filter screen, filter retainer and filter spring by pushing the retainer back against the spring. See Figure 8-38.
Inspection of Saginaw Pump Parts
- Wipe the bearing and shaft assembly with clean cloths; do not soak in cleaning solvent as the lubricant sealed into the bearing may be diluted by solvent. Wipe dry with clean lint-free cloths.
- Inspect the drive shaft for wear and check the ball bearing for roughness or noisy operation. If the ball bearing must be replaced, press the new bearing on shaft with a tool that applies pressure on the inner race only. If the needle bearing is to be replaced use Replacer J-6280 and drive the bearing into the pump body with the stamped face toward front of pump. Do not use excessive force and be sure the needles are free rolling after installation.
- Check fit of vanes in slots of rotor; vanes must slide freely but snugly in slots. Tightness may be relieved by thorough cleaning or removal of irregularities using Arkansas stone. Replace rotor if excessive looseness exists between rotor and vanes, and replace vanes if they are irregularly worn or scored.
- Inspect all ground surfaces of the rotor ring for roughness or irregular wear. Slight irregularities may be removed with a hard Arkansas stone. Replace ring if inside cam surface is scored or worn.
- Inspect the flat faces of the pressure plate and body for wear or scoring. These faces may be repaired by lapping until smooth and flat, after which all lapping compounds must be thoroughly washed away.
- Inspect the control valve bore in pump cover for scores or other damage. Hair line scratches are normal but heavy scratches or scores should be cleaned up with a cylindrical hard Arkansas stone. If this cannot be done satisfactorily, replace the cover.
- Inspect ground surfaces of the control valve for scores. Hair line scratches are normal but heavy scratches or scores should be cleaned up with a hard Arkansas stone. Replace the valve assembly if it is badly scored or if it is found to be the cause of low pump pressure. It is not practicable to disassemble the control valve. Make certain that control valve slides freely in bore of pump cover.
Assembly of Saginaw Pump
Assemble the pump by reversing procedure for disassembly, paying attention to the following items:
- Make sure that all parts are absolutely clean, and lubricate all moving parts with clean engine oil during assembly.
- Use new seals and gaskets.
- Make certain the bearings and shaft seal are firmly seated in their proper position. After the inner needle bearing is installed, the shaft seal must be installed with the word “outside” toward the front of the pump. Immerse the seal in Dynaflow Oil before installation. Using Installer J-6348 drive seal into body. See Figure 8-44.
NOTE: When viewed from the front or shaft end of pump, the arrow on the ring points in a clockwise direction, which is the direction of rotation of pump shaft.