SECTION 7-A  COIL SPRING SUSPENSION

7-1 SPECIFICATIONS

1958 Buick Suspension Specifications

1958 Buick Suspension Specifications

 

7-2 FRONT SUSPENSION SYSTEM

A one-piece stamped control arm assembly with attached ball joint, more rigid control arm shaft-to-frame mountings, new shock absorber mounting methods and front spring relocation are incorporated into Buick’s 1958 front suspension system.

 

7-3 CONTROL ARM ASSEMBLY

Upper Control Arm Assembly

A rugged one-piece stamped steel upper control arm assembly replaces the 1957 two-piece forged assembly. The upper ball joint is riveted by four rivets to the outer end of the upper control arm. The inner end of the upper control arm assembly is firmly anchored to the frame by the control arm shaft through heavier frame brackets. Two 1/2″ high tensile alloy bolts attach the control arm shaft to the reinforced frame bracket. See Figure 7-1.

1958 Buick Upper Control Arm and Front Shock Absorber

1958 Buick Upper Control Arm and Front Shock Absorber

Lower Control Arm Assembly

The lower ball joint is riveted by four rivets to the outer end of the lower control arm assembly. The inner end of the lower control arm assembly is rigidly anchored to the frame by the lower control arm shaft. New 1/2″ high tensile alloy bolts secure the lower control arm shaft to the frame, providing additional strength and stability.

Removal and Installation of Ball Joints

The ball joints used in 1958 may be replaced by carefully center punching and drilling out the rivets retaining the ball joints to the control arms. The joint may then be replaced by using Kit No. 1388219 which contains special bolts, nuts and lock washers to replace the rivets. Bolts must be installed from bottom with lock washer and nut on top.

Following installation, be certain the upper ball joint to knuckle nut is torqued to 30-40 ft. lb. The lower ball joint to knuckle nut must be torqued to 40-50 ft. lb.

NOTE: Be certain that replacement ball joint is lubricated immediately after installation.

 

7-4 SHOCK ABSORBERS

Front Shock Absorbers

The front shock absorbers for 1958, while basically the same as in 1957, are longer and are located outboard of the frame side rail, rather than within the front spring. The new shock absorbers no longer use the mounting eye but are provided with attaching studs on each end which bolt to the side rail bracket and to the lower control arm assembly. See Figure 7-2.

1958 Buick 1957 and 1958 Front Shock Absorbers

1958 Buick 1957 and 1958 Front Shock Absorbers

The control forces of the shock absorber are taken directly in the side rail rather than through the front cross member as in the past. To remove front shock absorbers, it is merely necessary to remove the upper and lower attaching nuts.

Rear Shock Absorbers

Two different rear shock absorbers are used in 1958; one for coil spring and the other for Air-Poise Suspension equipped cars. These rear shocks are not interchangeable as the Air-Poise shock is shorter in length and damage will result to the air spring if the incorrect shock is used.

To remove rear shock absorbers it is necessary to remove the mounting bracket from the frame after loosening the shock absorber-to­ bracket bolt. This is due to the redesign and relocation of the bracket. On Air-Poise Suspension cars, disconnect height valve links at lever or axle strut rods before shock absorbers are disconnected.

When installing rear shock absorber, tighten mounting bracket bolts to 15 to 25 ft. lbs. torque and upper and lower shock-to-bracket bolts from 60 to 80 ft. lbs. torque.

CAUTION: On Air-Poise Suspension cars, do not lift car to rebound position during rear shock absorber removal and re placement.

 

7-5 FRONT SPRINGS

The front springs have been repositioned further outboard because of the revisions in the control arms allowing greater spring travel and use of softer springs.

 

SECTION 7-B AIR-POISE SUSPENSION

7-6 SPECIFICATIONS

  1. Tightening Specifications
1958 Buick Tightening Specifications

1958 Buick Tightening Specifications

  • Test and Assembly Specifications ­ General
  • 1958 Buick Test and Assembly Specification

    1958 Buick Test and Assembly Specification

  • Compressor Production Limits & Fits
  • 1958 Buick Compressor Production Limits and Fits

    1958 Buick Compressor Production Limits and Fits

  • Height Control Valve Specifications
  • 1958 Buick Height Control Valve Specifications

    1958 Buick Height Control Valve Specifications

     

    7-7 DESCRIPTION AND OPERATION

    General Description

    Buick Air-Poise Suspension, available as optional equipment on all series equipped with power steering, utilizes air springs at all four wheels to replace the conventional coil springs of previous years.

    1958 Buick Air-Poise Chassis

    1958 Buick Air-Poise Chassis

    See Figure 7-4.

    1958 Buick Schematic of Air-Poise Suspension

    1958 Buick Schematic of Air-Poise Suspension

    The engine drives a compressor which supplies air at 280 psi pressure to an air storage tank. The tank acts as a reservoir and routes air to a manual override valve which reduces and regulates this 280 psi to a constant lower pressure. This is the air pressure which then is passed to three height control valves; one at each rear air spring and another that controls both front air springs. From the height control valves, air goes directly to the air springs.

    Air in the springs will exhaust with removal of load and for this purpose separate return lines are provided to return air from the air springs, through the height control valves, back to the manual override valve and to a tee fitting at the compressor where the air may either be used by the compressor or may exhaust out the air cleaner.

    All of the described operation is done automatically, the same as any conventional coil sprung car. However, for the driver’s convenience, a control is located at the dash which may be manually operated to raise the car when the need for changing a tire and wheel arises. See Figure 7-5.

    1958 Buick Manual Lift Control

    1958 Buick Manual Lift Control

    The bumper jack can then be used, as with coil spring suspension, to raise the car and then remove the wheel. This feature locks out the automatic control of the height control valves.

    Compressor

    A two-cylinder die-cast aluminum compressor with a 1 7/8 inch bore, a stroke of .9 inches and a displacement of 5 cubic inches is used.

    1958 Buick Compressor-Pump Assembly Mounting

    1958 Buick Compressor-Pump Assembly Mounting

    It has a stall pressure, or maximum built-up pres­ sure, of 280 psi; is located in front of the power steering pump and is bolted to it. A single belt drives the compressor at a speed ratio (compressor to engine ) of 1.15-1. A check valve at the air outlet fitting prevents leakage of air from the air tank through the compressor when the engine is not running.

    The front crankshaft babbit bearing and a double lip oil seal, are pressed into the front of the block. Steel cylinder sleeves are cast in and cannot be replaced. At the top of the block are two holes for each cylinder; one air inlet and a smaller exhaust which lead to exterior holes tapped for fittings.

    The heads also are die-cast aluminum and ribbed for cooling. They are interchangeable, side for side. A composition gasket is used between the heads and cylinder housing. One exhaust valve and one intake valve are located on the underside of the head. The exhaust valve is attached to a steel valve plate and the assembly is then a shrink fit in a recess in the head. It is not replaceable. The intake valve is positioned over two dowels which align with two holes in the cylinder block and is located between the head and block. It can be replaced if necessary.

    1958 Buick Air Compressor Cutaway

    1958 Buick Air Compressor Cutaway

    A three-ring, die-cast aluminum piston with a full floating piston pin is used. Piston pins are held in position by snap rings at either end of the pin opening in the piston.

    The connecting rods are die-cast aluminum. The rods and rod caps are babbitt plated at the bearing area and utilize lock plates that are crimped over the rod bolts after torquing.

    A cast crankshaft is used which is supported by the crankshaft bearing in the front of the housing and another babbitt bearing in a rear bearing plate. The driving pulley is driven by a woodruff key at the front of the crankshaft and held on by a special nut. The rear end of the shaft is splined and drives the power steering pump rotor. Pressed into the crankshaft at the rear main bearing journal is a small pin which drives the compressor oil pump. It en­ gages with a slot in the pump rotor. The shaft is drilled from the rear main bearing journal into the rod bearing journal and serves as an oil force feed to the connecting rod bearings. An air bleed hole is drilled through the center of the crankshaft, extending from the front of the shaft to the front counterweight. The pulley retaining nut on the crankshaft is vented.

    The vane type pump, having only two vanes, is mounted at the rear of the compressor and furnishes oil under a pressure of 20 psi to both main bearings and rod bearings. Oil is picked up from a shallow stand-pipe in the power steering reservoir, enters a hole in the rear bearing plate and is put under pressure by using only one of the two spring-loaded vanes of the pump. Oil is passed into a passage which houses a by-pass valve. The valve limits the pressure and by-passes excess oil. Oil at the regulated pressure then goes to the rear main bearings and also to the drilling in the bearing journal and finally to the connecting rod bearings. One additional drilling, in the rear bearing plate casting, routes oil at regulated pressure to a drilling in the rear of the cylinder block, through the block and up to the front crank­ shaft bearing where it enters through a hole in the bearing. All oil drains back to a sump in the bottom of the cylinder block where it is picked up and routed through a passage leading to the pump. The second vane of the pump puts the returning oil under pressure and re­ turns it to the power steering reservoir, with the oil entering through the longer of two stand-pipes.

    Air Tank

    A cylindrical air tank, having a capacity of 820 cubic inches, is positioned between the frame side rails just rearward of the front bumper face plate. It is pressurized at compressor stall pressure of 2SO psi and serves as an air reservoir and water trap. Two brackets are welded to the bottom at each end of the tank and the brackets are bolted to the frame. See Figure 7-8.

    1958 Buick Air Tank Assembly

    1958 Buick Air Tank Assembly

    There are two fittings welded to the top of the tank. The one on the left is for air under pressure coming from the compressor; the other is a Schrader type valve, normally used for manually filling the tank and diagnosis. Midway on the right end, another serves as the outlet fitting. At the bottom of the left end is a valve which should be opened periodically (at least every 5000 miles) for draining of any water and oil which may have come through the compressor. The inside of the air tank is coated with zinc chromate for protection against rust.

    Manual Override Valve

    The manual override valve assembly is bolted through a bracket to the frame front cross member at the right side. One of its functions is serving as a junction block for most of the air lines. It also reduces and regulates the high pressure coming from the tank to a working supply pressure of 125 psi. Incorporated in the exhaust side of the valve is the return flow control valve which restricts flow of air through the return lines. An important function of the override valve is to allow raising the car to its full rebound position when the need for changing a wheel or tire arises. This is done by raising a lever on the valve through a Bowden control wire which extends into the driver compartment through the right side of the dash. A filter is used in the air tank inlet line at the override valve.

    1958 Buick Manual Override Valve

    1958 Buick Manual Override Valve

    When the lever is in its normal down position, the air routing is from the override valve, through air supply lines to the two height control valves in the rear and the one height control valve in the front. The pressure within these lines is always 125 psi. When the lever on the override valve is raised, the exhaust line leading to the air cleaner is shut off, and the air return lines are opened to the same pressure  as in the pressure lines. See Figure 7-10.

    1958 Buick Override Valve - Lift Condition

    1958 Buick Override Valve – Lift Condition

    This pressure feeds to the height control valves and the valves allow the car to be raised approximately 5 1/2 inches. When the lever is returned to its normal position, the air return lines are shut off from the 125 psi supply pressure and the exhaust passage leading to the return flow control valve is opened, allowing the excess air to rapidly bleed out from the return lines through this valve until pressure lowers to 50 psi.

    When it becomes necessary to change a tire or wheel, or if the car must be jacked up for any reason, the override valve must be actuated so that the car will be raised to a full rebound position. The bumper jack is then used in the conventional manner.

    Height Control Valves

    Three height control valves are used; one for each rear wheel and one for both front wheels.

    1958 Buick Rear Height Control Valve

    1958 Buick Rear Height Control Valve

    All the valves are identical in construction and operation with the exception of the lever arms which are longer on the rear valves. The valves work together to keep the trim height of the car constant regardless of weight load or level of the ground. They do this by controlling the air flow into or out of the air springs.

    Each rear height control valve is mounted to a bracket by two cap screws and the bracket is bolted to the front side of the frame rear spring cross member. The two holes in the bracket are elongated to allow positioning of the valves when trim height connections are necessary. The valve operating arms are connected to links which in turn are bolted to the rear axle strut rods. Vertical motion of either rear wheel will move the link and therefore the arm. The direction of vertical motion will determine whether the valves will allow the air springs to take in more air or exhaust some of the existing air. Rear height control valve links on 49-69 models are different from other models, the difference being in length.

    1958 Buick Rear Height Control Valve Assembly

    1958 Buick Rear Height Control Valve Assembly

    The front height control valve is located on a bracket inside the front frame cross member and in line with the center line of the car.

    1958 Buick Front Height Control Valve Assembly

    1958 Buick Front Height Control Valve Assembly

    One end of a link is connected to the valve arm with the other end connected to a lever. The lever is clamped to the stabilizer bar and allows for positioning of the front height control valve when trim height corrections are needed at the front. Whenever either front wheel or both move up or down, the stabilizer bar will twist and transfer this motion to the valve link and arm. The valve will then allow the air spring to either exhaust or take in additional air, depending on the direction the wheel moves.

    Two features are built into all height control valves to prevent opening and closing of the valves each time a small bump or series of small bumps are encountered. The wheels can either be lowered approximately 3/8″ from their normal trim or “neutral” position, or raised approximately 3/8″ from this neutral position before the valves will open or close. This is due to a “dwell” period built into the valve.

    To reduce sensitivity further, a silicone dash­ pot provides approximately one second delay in the operation of the valve when road conditions momentarily move the valve arm out of the neutral position. This insures against filling or exhausting of the air springs unless an actual trim height correction is needed, such as when adding or reducing weight load to the car. See Figure 7-14. Three filters are used at each height valve; one in each fitting.

    1958 Buick Height Control Valve - Cover Removed

    1958 Buick Height Control Valve – Cover Removed

    When a car is at curb weight, the trim height will be correct. As soon as weight is added, such as the addition of passengers, the car lowers and the height control valve arm moves up. See Figure 7-15.

    1958 Buick Height Valve Arm Action

    1958 Buick Height Valve Arm Action

    A Schrader type valve in the air supply (intake) fitting is mechanically opened. A second Schrader valve in the fitting is opened by supply line pressure. With both intake valves open and the exhaust closed, air is allowed to flow into the air springs, until the car is raised to its normal trim height and all valves are closed.

    When weight is removed and the car raises, the valve arms move down and open the Schrader type exhaust valves, thereby allowing excess air to pass out of the air springs until the car lowers to its normal trim height and the valves close.

    Trim height settings must be as close as possible to the specified limits. By deviating out­ side the limits, the riding qualities will be materially affected.

    Cross Flow Control Tee

    To materially improve cornering stability a cross flow tee is provided for the front air springs. It is inserted in the air supply line between the air springs and the height control valve and attached to the height control valve. See Figure 7-13. Inside the tee are two check

    balls, one for each spring, which are forced off their seats when pressure is fed into the air springs, but are forced toward the seats when exhaust pressure comes from the springs. The seats, however, have metered orifices which allow a restricted flow of air. Therefore, when cornering, air from the high pressured spring cannot flow freely to the spring with lesser pressure.

    Air Springs

    Air springs are located in the same position as coil springs on other models. They are air chambers consisting of metal containers, called domes, into which rubber diaphragms are positioned at the bottom. The diaphragms are com­ pressed by means of specially shaped plungers which are below the diaphragms and connected to the suspension. See Figure 7-18.

    1958 Buick Air-Poise - Front Suspension

    1958 Buick Air-Poise – Front Suspension

    The domes are stampings with air fittings welded into the sides. The diaphragms are then positioned into the domes with diaphragm guides placed up and against the diaphragms. Then the lips of the domes are crimped over to securely hold the guides in position and form an assembly.

    Diaphragms are rolling seals made of two­ ply nylon cord with a layer of natural rubber vulcanized on the inside and a layer of ozone resistant rubber vulcanized to the outside. Both front and rear spring diaphragms have a solid steel bead at the outer edge, but only front diaphragms have a solid steel bead around an opening in their centers. The front diaphragms are held to the plungers by six cap screws and a diaphragm retainer clamp. Front plungers are hollow and have an opening at top to match the diaphragm opening and allow for flow of air into or out of the plunger. The rear diaphragms are solid at the center and incorporate a plug in their design which centers and holds the diaphragm to the solid rear plunger. See Figure 7-19.

    1958 Buick Rear Air Spring Assembly

    1958 Buick Rear Air Spring Assembly

    At the very bottom of each plunger, both front and rear, is a plunger pilot, which is se­ cured to a pilot guide by a spring pin. The pilot rides on top of a spherical bearing which is down in the pilot guide. A seal is positioned over the guide and pilot to exclude dirt, etc. The bearings handle all angular motion of the air springs.

    The bottoms of the rear spring plunger pilot bearings fit into a select hole in a plunger shaft bearing plate. The plate itself is bolted to a bracket on the rear axle housing. Plunger pilot bearings on the front springs are retained to a spring seat adapter by a spring nut. See Figure 7-20.

    Rear air spring assemblies are held to the rear cross member by two self-tapping screws and two clips.

    1958 Buick Rear Spring and Valve Assembly

    1958 Buick Rear Spring and Valve Assembly

    One clip is welded at the top of the dome and the screw secures the clip to the cross member. The other clip butts under the dome lip and is secured to the side rail by the screw. Front air spring domes have two tapped fittings welded to the top and are held to the front cross member by two cap screws. See Figure 7-16.

    1958 Buick Rear Air Spring Mounting

    1958 Buick Rear Air Spring Mounting

    1958 Buick Front Air Spring Mounting

    1958 Buick Front Air Spring Mounting

    Diaphragms cannot be replaced separately. The rear air spring dome, diaphragm and diaphragm guide are serviced as one assembly. On front air springs, the plunger is also included in the assembly.

    Rear air spring assemblies used on 49-69 models are different in size from others and are not interchangeable with them.

    1958 Buick Air-Poise - Rear Suspension

    1958 Buick Air-Poise – Rear Suspension

    The normal pressure within the air springs is approximately 100 psi. As car weight load is increased, the height control valves allow more air to enter the springs so that trim height remains constant. Pressure within the springs then goes up. The reverse takes place when decreasing load weight.

    Return Flow Control Valve

    As previously mentioned, the return flow control valve is located in the manual override valve on the exhaust side. As air exhausts from the air springs under certain conditions, such as unloading the car, it flows through the exhaust, or return lines, to the override valve and through the return flow control valve. The valve provides rapid flow through the return lines when pressure exceeds approximately 50 psi and slower flow when pressure is less than approximately 50 psi. The air returns to the tee fitting at the compressor and air cleaner.

    Thus, some back pressure is retained to give additional control when rounding curves, during braking and when accelerating. Due to dynamic forces exerted on the car during these three operating conditions, the exhaust valves in some of the height control valves would be opening and discharging air too rapidly. At the same time, the intake valves would be opening in some of the other height control valves, allowing those valves to take in air. This would trim the car when the dynamic forces were present, and would re-trim after the conditions no longer were present, which would be undesirable.

    Such would be the case when rounding a long curve at higher speeds. The weight would be thrown outward to the outer springs and would lessen on the inner springs. The height valves would level the car if some assistance were not available, while still in the curve, and then would have to trim after the turn had been made. The return flow control valve gives this assistance by providing different discharge rates, depending on the pressure within the springs.

    If the pressure within the air spring is substantially above its normal 100 psi, a rapid discharge rate is allowed, thereby allowing quick trim compensation. If the pressure within the spring is equal to or less than normal, only a slow discharge is allowed. Therefore, when the aforementioned dynamic condition takes place, only a very slow discharge from the inner springs is allowed and very little air is taken in at the outer springs. No noticeable trim compensation is experienced by the passengers.

    When a fast brake application is made and also when accelerating rapidly from a standing start, no trim sensation is noticed.

     

    7-8 TROUBLE DIAGNOSIS

    Complaints

    1. Hard ride or car bottoms or has a pounding sensation.
      • Check the trim height and correct if necessary.
      • Check the shock absorbers for proper action and control.
      • Inspect the rubber compression bumpers for damage. Replace if necessary.
      • Check the operation of the height control valves. See Par. 7-12, sub. par. 3.
      • If height control valves do not raise the car when weight is applied or lower the car when weight is removed, check the operation of the manual override valve pressure regulator. If the supply pressure is low, adjust the valve, or replace if necessary, to bring the supply line pressure to a recommended 125 psi with air flow. (Par. 7-11, sub. par. b.). The minimum pressure in the air tank should be 150 psi when checking the pressure regulator.
      • If the pressure regulator is working properly and the air tank pressure is at least 150 psi, the trouble is probably in one of the height control valves.
    2. Car rides high and will not lower even after adjusting height valves.
      • Before adjusting height valve position, be sure that the manual lift control knob is pushed in and that the Bowden control wire is properly adjusted at the manual override valve.
      • Disconnect the manual override valve to compressor inlet tee hose at the override valve. Then loosen the return flow control valve nut on the override valve. If a large quantity of air exhausts and the car lowers to a normal trim height, then the return flow control valve should be cleaned or replaced if necessary.
      • If the front end or one rear corner is up and will not lower to trim height by adjusting the height control valves, then the height control valve is at fault. Remove the valve and inspect it by removing the cover. Move the external lever not more than 1 inch on a rear valve and not over % inch on a front valve. Observe the action of the valve cores. A sticking dashpot will prevent either or both valve cores from opening. A weak or broken torsion spring will have the same effect. See Par. 7-10, sub. par. b.
    3. Poor Handling
      • If the car rolls excessively, remove and inspect the cross flow control tee which is located to the rear of the front height control valve. Blow into the nut end of the valve and feel whether the flow of air is good. Then blow through each side of the tee and this should give a restricted flow. Replace the valve if not operating properly.
      • When Air-Poise Suspension is functioning properly, there will be very little trim correction when cornering. The heavier the load , the less the correction while in a turn. If the manual override valve pressure regulator is set too high, the car will lean slightly when coming out of a curve. A return flow control valve that is not restricting return air flow at all will have the same effect to a lesser degree. If the override valve pressure regulator is set too high, adjust to proper pressure or replace if necessary. If the return flow control valve is at fault, repair or replace if necessary.
      • If the car leans in one direction when driven for a few miles and will settle to correct trim height when the car is stopped, look for a failed dashpot in the height control valve on that side that was up. If the dashpot is not at fault, check the supply line pressure for a high reading, which would be caused by the override valve pressure regulator being set too high or not operating properly.
      • If trim height corrections take place after a hard brake application, inspect the return flow control valve at the manual override valve to be sure it is working properly. A return flow control valve that is functioning correctly will release a fairly large amount of air initially. When a one-passenger load is removed and after about 2 seconds, the flow will decrease very noticeably. To check the valve operation, disconnect the return pressure hose at the compressor inlet tee and add at least a one-passenger weight load. Allow time for the car to raise to normal trim height and remove the weight load. Then listen to the air exhausting from the disconnected hose. If the return flow control valve is working properly, inspect the front suspension for excessive friction. Lubricare the front suspension if necessary.
      • If the front end lowers excessively after prolonged periods of acceleration. Check the operation of the cross flow control tee. See sub. par. a-3 (a).
        NOTE: It is normal for a slight amount of trim correction to take place after prolonged periods of braking or acceleration.
    4. Supply pressure low – manual override valve pressure regulator operating correctly and air tank pressure low.
    • Take a pressure reading at the air tank. Start the engine and run at 1500 RPM for 2 1/2 minutes. Then take another pressure check at the air tank to see whether the pressure increases noticeably.
    • The pressure should have increased a minimum of 50 psi with a pressure in the air tank of 100 psi to 150 psi when first starting the engine.
    • If pressure increase was less than 50 psi, leak-check with bubble solution at all air tank connections and the pressure line fitting at the override valve.
    • If no leaks were found, check for a clogged suction hose and pipe. If they are open, remove the compressor for disassembly, inspecting the suction and pressure valves in each head, and the rings. Replace the intake valve and rings if necessary. If the pressure (exhaust) valve is defective, the head and valve assembly will have to be replaced.

    Air Leak Checking Procedures-External

    1. Pull the manual override valve “lift” knob at the dash panel to put the car in the lift position. This will pressurize all fittings and springs to approximately 125 psi.
    2. Apply bubble solution to the suspected fittings or parts. If any doubt exists, use the solution on all fittings and parts.

    NOTE: If parts or fittings to be tested are covered with dirt or foreign matter, use a stiff brush and clean prior to testing.

    1. At l height valves, check around the covers, lever shafts and air line fittings. If a leak should exist at the lever shaft, the height control valve must be replaced.

    NOTE: If leakage is suspected at the height control valve, but does not show up during the solution test , remove the valve. Screw tool J-7143 into the air spring line fitting on the valve and pressurize to 125-130 psi. Then submerge in water.

    1. Apply solution to all fittings on the manual override valve. If a leak is detected and tightening does not correct, then install new O-rings and re-check.
    2. With the car still in the lift position, apply solution to visible portions of the diaphragms and also at the crimped edges of the domes.

    NOTE: If leakage is suspected at the air spring assemblies, but does not show up during the bubble solution test, remove the doubtful air spring assembly. Pressurize the air spring to only 25 psi using Tool J-7143 and submerge in water.

    CAUTION: Care must be exercised so that excess pressure is not used during this test with the air spring removed. Damage could result to the air spring and person.

    1. If a leak is detected at diaphragm sealing lip area, exhaust all pressure from air spring assembly and force the diaphragm lip up into the dome approximately 1 1/2″.
      • Place a medium film thickness of silicone paste (Dow Corning DC-4) around the wall of the dome in the area of the normal diaphragm lip contact.
      • Pull the diaphragm down to its normal position using a twisting motion.
    2. Push the “lift” knob in so that the car returns to normal trim height. Disconnect check valve and high pressure hose at the compressor and with at least 80 psi in the air tank, pour a small amount of bubble solution into the check valve inlet to see whether the check valve is leaking. If a leak is found, replace the valve.
    3. Use bubble solution at all fittings on the air tank. Tank must have a minimum pressure of 80 psi when checking.
    4. If a leak still exists, somewhere in the system, use bubble solution on all air lines.

    Air Leak Checking Procedures-Other than External

    • Return Pressure System Leak
      • A return pressure leak at a height control valve exhaust Schrader core may be deter­ mined by disconnecting the return flow control valve to compressor inlet tee hose and using bubble solution on the end of the hose.
        NOTE: This must be done without any weight change on the car. If weight is added, such as leaning on a fender, and t hen removed, the height valves would automatically exhaust air. If a leak is noted at the end of the hose, then the air return lines at all height valves should be disconnected and bubble solution used on the valve fittings.
      • In stubborn cases where the leakage is very slight, it may not show at the air return hose. In such cases, check as described in Par. 7-10, sub. par. 2-(k).
    • Height Control Valve Inlet Check Valve
      • If the supply pressure system bleeds down due to a fitting, check valve or any other leak and the front springs or either rear spring bleeds down at the same time, it is necessary to inspect the height valve inlet check valve (the Schrader valve core uppermost in the valve stem) at the same time that the pressure leak is repaired.
      • If the inlet check valve is dirty, it may be cleaned and reinstalled. If it is corroded, it must be replaced.
    • A leaking manual override valve seat.
      • If it has been determined through testing that there are no leaks at the height control valve exhaust cores and all external checks show no other reason for a high pressure leak, then look for a leak at the manual override valve seat. Be sure that the manual lift control knob is pushed in and that the Bowden control wire is adjusted so that the lever is against the stop on the override valve. Then check for a leak at the exhaust hose, making sure no weight is added or removed from the car while checking.

     

    7-9 REMOVAL AND INSTALLATION OF COMPONENT PARTS

    Front Air Springs

    1. Removal
      • Jack up front of car at center of spring cross member.
      • Place floor stands under fronts of frame side rails and then lower the jack.
      • Remove tire and wheel assembly.
      • Remove the air spring dome outer attaching bolt which is on top of the cross member and below the cutout in the upper control arm. Remove the other bolt which is approximately six inches toward center of cross mem­ber from first. See Figure 7-23.
    1958 Buick Front Air Dome Attaching Bolts

    1958 Buick Front Air Dome Attaching Bolts

  • Remove spring nut at bottom of pilot bearing on air spring to be removed. See Figure 7-24.
  • 1958 Buick Front Air Spring Assembly

    1958 Buick Front Air Spring Assembly

  • Disconnect height control valve link from clamp-bracket on stabilizer bar. See Figure 7-25.
  • 1958 Buick Front Height Valve Assembly

    1958 Buick Front Height Valve Assembly

  • Disconnect air line at fitting on air spring dome. This will exhaust air from both front air springs, but will not affect the rear. See Figure 7-25.
  • Place floor jack under spring seat of air spring to be removed but do not raise car off floor stands.
  • Disconnect stabilizer bar link at lower control arm. See Figure 7-24.
  • Remove bolts at lower control arm inner shaft and lower the jack and control arm assembly.
  • Remove air spring assembly.
  • Replacement
    • Position air spring assembly up into cross member opening.
    • Raise lower control arm assembly into position and install lower control arm inner shaft bolts.
    • Position plunger pilot bearing into hole in spring seat adapter and secure with spring nut.
    • Place jack under spring seat, but do not raise car off floor stands.
    • With one man below to position and hold spring up, and another on top, replace dome bolts and lock washers and tighten. See Figure 7-23.
    • Connect air line to fitting at air dome using new O-ring.
    • Connect stabilizer bar link to lower control arm.
    • Operate height control valve link to pressurize air spring. Do not move the valve lever more than 1/2″ when moving the link.
    • Fill air tank at filler fitting with available air pressure.
    • Use bubble solution at air line fitting to check for leaks.
    • Connect height valve link to clamp bracket on stabilizer bar. See Figure 7-25.
    • Remove jack from spring seat and position at center of spring cross member. Raise car and remove floor stands. Lower and remove jack.
  • Rear Air Springs

    1. Removal
    • Jack up car at center of axle housing and place floor stands under frame side rails.
    • Lower jack and allow axle assembly to lower close to a full rebound position.
    • Disconnect height control valve link at axle strut rod on spring being removed. See Figure 7-26.
    1958 Buick Rear Height Valve Assembly and Bearing Plate

    1958 Buick Rear Height Valve Assembly and Bearing Plate

  • Disconnect air line at fitting on air dome of spring being removed, allowing air to exhaust from spring.
  • Remove 2 bolts retaining plunger bearing plate to rear axle housing and pull plunger loose from diaphragm plug. Remove plunger and bearing plate assemblies. See Figure 7-26.
  • Remove the two self-tapping screws at the dome upper and side retainer brackets. See Figure 7-27.
  • 1958 Buick Rear Air Spring Assembly Schematic

    1958 Buick Rear Air Spring Assembly Schematic

  • Remove spring.
    1. Replacement
    • Reverse steps (g) through (d) used in removal.
    • When connecting air line at dome fitting, use new O-ring.
    • Before connecting height valve link to strut rod, raise height valve lever, but not over 1″, to allow air to inflate air spring assembly.
    • Use bubble solution and check at air dome fitting for leaks.
    • Reverse steps (c) through (a) used in removal.

    CAUTION:

    • Never disconnect radius rod or torque tube unless all air is exhausted from rear air springs, as damage to air springs may result.
    • Always disconnect height valve links at lever or axle strut rods if shock absorbers are to be disconnected.
    • Never move rear height control valve levers manually more than 1″ in either direction from a neutral position, measured at end of lever. Internal damage could result which would affect the riding qualities of the car.

    Front Height Control Valve

    1. Removal
    • Exhaust all air at filler fitting on air tank.
    • Jack up front of car at center of spring cross member.
    • Place floor stands under fronts of frame side rails and remove jack.
    • Disconnect height valve link at clamp bracket on stabilizer bar. See Figure 7-25.
    • Remove front spring cross member lower cover.
    • Disconnect all air lines at height valve allowing cross flow control tee to remain with air lines. See Figure 7-25.
    • Remove two valve bracket mounting bolts at front of cross member and remove bracket and valve assembly.
    • Remove bracket from height valve.
    1. Replacement
    • Reverse steps (h) through (f) used in removal. Use new O-rings at all air line fittings.
    • Before replacing spring cross member lower cover-
      • Fill air tank at filler fitting with available air pressure.
      • Operate height valve link to pressurize front springs. Do not move the valve lever more than 1/2″ when operating the link.
    • Use bubble solution at air line connections on height valve to check for leaks.
    • Reverse steps (e) through (a) in removal.
    • Check valve operation by applying weight to front bumper.

    CAUTION: Never move front height control valve lever manually more than 1/2″ in either direction from a neutral lever position, measured at end of lever. Internal damage could result which would affect the riding qualities.

    Rear Height Control Valve

    1. Removal
      • Jack up car at center of axle housing to desired working height.
      • Use a block 1/2″ shorter than normal trim height and position between frame and axle housing. See Figure 7-28.
    1958 Buick Blocking Up Body

    1958 Buick Blocking Up Body

  • Place floor stands under axle housing and remove jack.
  • Exhaust all air at air tank filler fitting. (e) Disconnect height valve link at valve lever. See Figure 7-26.
  • Disconnect all air lines at height control valve.
  • Remove the two bracket-to-valve body bolts and remove valve.
  • Replacement
    • Reverse steps (g) and (f) used in removal. Use new O-rings at all air line fittings. (b) Fill air tank at filler fitting with available air pressure.
    • Raise height valve lever, but not over 1″, to fill air spring and valve body.
    • Check all air fittings on height valve with bubble solution.
    • Connect height valve link to valve lever. (f) Reverse steps (c) through (a) in removal.
    • Check trim height and correct if necessary.
    • Check valve operation by applying weight to rear of car.

    Manual Override Valve

    1. Removal
      • Exhaust air out of air tank at filler fitting.
      • Jack up car at center of front spring cross member to desired working height.
      • Disconnect all air lines at override valve. See Figure 7-29.
    1958 Buick Manual Override Valve View

    1958 Buick Manual Override Valve View

  • Disconnect Bowden control-wire assembly at valve.
  • Remove the valve-to-bracket bolt at lower front of valve.
  • Remove valve assembly.
  • Replacement
    • Reverse steps (f) through (b) in removal, using new O-rings at all fittings.
    • Fill air tank at filler fitting with available air pressure.
    • Check the adjustment of the bowden control wire to insure correct lift action.
    • Operate lift control on dash to put car into lift position.
    • Use bubble solution at all air fittings and check for leaks.
    • Release lift control to lower car to normal trim height.
  • Air Compressor-Power Steering Pump Assembly

    1. Removal
      • Exhaust air out of air tank at filler fitting.
      • Loosen the vented pulley nut and re- move.
      • Remove compressor belt and pulley.
      • Disconnect power steering pump hoses. (e) Remove air inlet tee at compressor.
      • Remove high pressure hose and check valve at compressor.
      • Disconnect compressor-pump assembly from brackets and remove from car.
      • Remove oil from reservoir.
      • Remove the two compressor to pump bolts and separate compressor from pump.
    2. Replacement
      • Install two guide pins, J-7003 (3/8-16 x 3″) in compressor.
      • Carefully align pump on guide pins to avoid damage to seal and push into contact with compressor. Remove pins and install two compressor-to-pump bolts. Tighten to 25-30 ft. lbs. torque.
      • Mount compressor-pump assembly in brackets. Install but do not tighten bolts.
      • Install high pressure hose and check valve to compressor.
      • Connect inlet tee at compressor.
      • Connect power steering hoses to pump.
      • Install compressor pulley and belt. Securely tighten vented pulley nut.
      • Adjust belt tension and tighten mounting bolts. Tension should be 30 to 35 ft. lbs. torque on pulley nut to slip old belt (40 to 45 ft. lbs. torque to slip new belt).
      • Fill reservoir with Dynaflow oil, run engine and check for leaks. Do not remove reservoir cover when engine is running.
    1958 Buick Air Compressor - Exploded View

    1958 Buick Air Compressor – Exploded View

    CAUTION: Since the compressor is de­ pendent upon the power steering oil pump for lubrication, it is most important that reservoir oil level be at full mark at all times. After replacing compressor-pump assembly and running engine, check oil level and add oil as needed.

     

    7-10 DISASSEMBLY, ASSEMBLY AND ADJUSTMENT

    Compressor and Pump Assembly

    1. Disassembly
      • Remove all foreign material from exterior of compressor using wire brush and air hose.
      • Invert compressor and remove four bolts and lock washers which retain sump cover plate to block. See Figure 7-31.
    1958 Buick Compressor - Remove Sump Plate

    1958 Buick Compressor – Remove Sump Plate

  • Remove plate and square-cut rubber sealing ring. Allow all remaining oil to drain out.
  • Turn compressor over and remove six head bolts from each cylinder head. See Figure 7-32.
  • 1958 Buick Compressor - Remove Cylinder Heads

    1958 Buick Compressor – Remove Cylinder Heads

  • Remove heads and gaskets. Heads may be tapped lightly with a rawhide mallet to break loose. Do not pry loose.
  • Scrape off any gasket material on heads or block.
  • Invert compressor and work through the sump opening to remove piston and rod assemblies.
  • Bend back the tabs on the rod bolt lock­ straps and remove the bolts, lock straps and caps. See Figure 7-33.
  • 1958 Buick Compressor - Remove Rod Lockstraps and Caps

    1958 Buick Compressor – Remove Rod Lockstraps and Caps

  • Push pistons and rods out of top of block. See Figure 7-34.
  • 1958 Buick Compressor - Remove Pistons and Rods

    1958 Buick Compressor – Remove Pistons and Rods

  • Remove snap rings at each end of piston pin using No. 1 Truarc pliers.
  • Remove pin by pressing out of piston and rod.
  • Remove the three rings from piston. See Figure 7-35.
  • 1958 Buick Piston and Rod Assembly

    1958 Buick Piston and Rod Assembly

  • Remove the two bolts retaining bearing plate and pump assembly to block. See Figure 7-36.
  • 1958 Buick Compressor - Remove Bearing Plate and Pump Assembly

    1958 Buick Compressor – Remove Bearing Plate and Pump Assembly

  • Carefully slide bearing plate and pump assembly from crankshaft to prevent damage to bearing.
  • Remove the square-cut rubber sealing ring and two small O-rings from bearing plate and pump assembly.
  • Remove the lubrication by-pass valve plug, spring and plunger.
  • Remove the test plug which is below the by-pass valve opening.
  • Remove crankshaft from block through the rear opening. See Figure 7-37.
  • 1958 Buick Compressor - Remove Crankshaft

    1958 Buick Compressor – Remove Crankshaft

  • Place a steel washer of approximately 1 1/2″ inside diameter around outer face of seal opening to protect the bore.
  • Insert tip of screw driver well into the rubber seal to insure contact with metal flange and pry upward. Use caution to prevent bearing damage while removing seal. See Figure 7-38.
  • 1958 Buick Compressor - Remove Front Oil Seal

    1958 Buick Compressor – Remove Front Oil Seal

  • Assembly
    • Wash all metal compressor parts in a suitable solvent and blow them dry with air. Inspect all parts, openings and passages to be sure they are open and clean.
    • Inspect the front seal bore for any roughness or scores. Any such damage should be dressed down before installing a new seal.
    • Install a new seal in bore using Seal Installer J-7079. Install flush with top of bore. See Figure 7-39.
  • 1958 Buick Compressor - Replace Front Oil Seal

    1958 Buick Compressor – Replace Front Oil Seal

  • Lubricate the front bearing and oil seal with Dynaflow oil. Install crankshaft and push through the oil seal and bearing with a slow, steady pressure. Be sure the oil passage in shaft is open. See Figure 7-40.
  • 1958 Buick Compressor - Remove Crankshaft

    1958 Buick Compressor – Remove Crankshaft

  • Install by-pass valve plunger, spring and plug into by-pass valve opening in bearing plate. Use a new O-ring on plug. See Figure 7-41.
  • 1958 Buick Compressor - Install By-Pass Valve Assembly

    1958 Buick Compressor – Install By-Pass Valve Assembly

  • Replace test plug using new O-ring.
  • If any part of the bearing plate-pump assembly is defective, the assembly must be replaced. Do not disassemble the plate-pump assembly. Install two small O-rings in the oil passage openings and the square-cut rubber sealing ring over the first shoulder on the bearing plate, using new O-rings and sealing ring.
  • Rotate crankshaft until oil pump drive pin is located midway between the two small lower oil passages in the block. Position the slot in the pump rotor by rotating the rotor so that the slot aligns with the pin.
  • Ease the plate-pump assembly into position over the shaft. DO NOT FORCE. Rotate plate-pump assembly back and forth slightly so drive pin aligns with slot in pump rotor, and then press the assembly forward.
  • Install the two retaining bolts and tighten to 45-55 inch lbs. torque. See Figure 7-42.
  • 1958 Buick Compressor - Install Bearing Plato and Pump Assembly

    1958 Buick Compressor – Install Bearing Plato and Pump Assembly

  • Inspect piston, pins and rods for excessive wear and replace if necessary.
  • Position the rod into the piston and press pin through rod and piston.
  • Replace snap rings at each end of piston pin and be sure they are seated in the grooves in piston.
  • Before replacing rings, press the rings down into the bore with skirt of piston and check end gaps. See Par. 7-6. Sub. Par c.
  • Replace rings on pistons with the raised dot on each ring in an up position. Stagger ring openings 120 ° apart. Care must be exercised when installing the two upper rings so that the correct ring is used in the correct groove. The rings and grooves vary in height dimensions.
  • Use a hand hone to break the glaze in the bores so that the rings will seat.
  • Insert piston and rod assembly through the ring compressor, J-7081, until piston skirt extends below the bottom of the compressor.
    Install the assembly into the bore with the long ear of connecting rod toward the top of the block. See Figure 7-43.

  • 1958 Buick Compressor - Install Piston and Rod Assembly

    1958 Buick Compressor – Install Piston and Rod Assembly

  • Press piston and rod assembly down into bore until the rod contacts the crankshaft rod journal. Rotate the shaft if necessary and attach the rod cap to the rod with Jockstrap and the two rod bolts. The identification marks on the rod and cap should both be on the same sides. Tighten rod bolts to 25-30 inch lbs. torque and then bend Jockstrap tabs over bolt heads. See Figure 7-44.
  • 1958 Buick Compressor - Install Rod Caps

    1958 Buick Compressor – Install Rod Caps

  • Install the remaining rod and piston assembly in a similar manner.
  • Place a new square-cut rubber sealing ring in the channel around the sump opening. Replace the sump cover plate and tighten to 40-50 inch lbs. of torque. See Figure 7-45.
  • 1958 Buick Compressor - Install Sump Cover Plate

    1958 Buick Compressor – Install Sump Cover Plate

  • Install a new head gasket on block using a few drops of oil to hold gasket in position. DO NOT USE SEALER OR CEMENT.
  • Be sure intake valve is located correctly over dowel pins on the head. Replace the head being certain that dowel pins align with the matching holes in the cylinder block. See Figure 7-46.
  • 1958 Buick Compressor - Install Head and Suction Valve

    1958 Buick Compressor – Install Head and Suction Valve

  • Install head bolts and tighten to 100-120 inch lbs. of torque. Alternate the tightening sequence from side to side to insure a good seal. See Figure 7-47.
  • 1958 Buick Compressor - Head Bolt Tightening

    1958 Buick Compressor – Head Bolt Tightening

  • Install the remaining cylinder head in a similar manner.
  • Height Control Valves

    1958 Buick Height Control Valve - Exploded View

    1958 Buick Height Control Valve – Exploded View

    1. Disassembly
      • Remove the four cover screws, cover and O-ring.
      • Remove the two screws retaining the dashpot retainer plate and remove the plate by sliding it out from under the dashpot bracket.
      • Remove the dashpot.
      • Remove the O-rings from the three line fittings.
      • Remove the external air supply fittings, filter and O-ring.
      • Remove the other two air line fittings and the filter under the air return fitting.
      • Remove the valve stem.
      • Remove the three O-rings from the fit­
      • Remove the copper stop clip from the exhaust valve Schrader core. Use a fine pair of needle nose pliers to hold the core stem and then pull the clip loose from the stem end with needle nose pliers. Care must be used so that the stem is not bent.
      • Remove the exhaust Schrader core from the valve body, the intake core from the bottom of the intake valve stem and the intake check valve core from the upper end of the valve stem. Use J-6888 for removal of all three cores. See Figure 7-49.
    1958 Buick Height Control Valve

    1958 Buick Height Control Valve

  • Assembly
    1. Clean all parts in a suitable solvent and inspect. Do not use a solvent that will injure rubber since the seal at the lever shaft will be affected.
    2. Use new O-rings at all points.
    3. Install the intake check valve at the top of the valve stem and the intake valve at the bottom of the stem. Install the exhaust valve into the height valve body. Tighten all three valves using J-6888. See Figure 7-50.
  • 1958 Buick Height Control Valve - Schrader Cores

    1958 Buick Height Control Valve – Schrader Cores

    • Install the exhaust valve core clip on the core using needle nose pliers to hold the core stem. Be careful not to bend the stem. In­ stall the filter inside the valve body and over the top of the exhaust valve and install a new O-ring on the air return (exhaust) fitting. Screw the fitting into the valve body and tighten.
    • Install the intake valve, intake check valve and stem assembly into the valve body, using a new O-ring on the stem and then tighten. Install a new O-ring on the upper portion of the stem and install the filter and air supply (intake) fitting and tighten.
    • Install the filter in the valve body at their spring fitting. Use a new O-ring on the air spring fitting and install the fitting; then tighten securely. See Figure 7-51.
    1958 Buick Height Valve Fittings

    1958 Buick Height Valve Fittings

  • At this point, the intake and exhaust valves must be checked for correct positioning so that they open at the correct time. If either valve, the exhaust core or the intake core (but NOT the intake check valve core) is replaced, the following procedure should be used:
    • Connect hose J-7143 to an air pressure line and reduce the line pressure to 10-20 psi. Do not exceed 20 psi. Install the other end of Hose J-7143 at the air return exhaust fitting and tighten.
    • Place the .049 side of Gauge J-7148-1 between the operating lever stop, (on the side furthermost from the valve cores) and the middle ear of the operating lever. Insert Wedge Gauge J-7148-2 between the other side of the stop and lever ear and press down securely. Gauge J-7148-2 is a wedge and should hold the feeler gauge so that it does not fall out. See Figure 7-52.
  • 1958 Buick Height Valve Core Setting

    1958 Buick Height Valve Core Setting

  • The incoming air will unseat the exhaust valve core. Therefore, use a suitable tool, such as a thin blade screwdriver, and using a moderately light pressure, press against the exhaust core at the core seal seat. A slight amount of air leakage should be heard. See Figure 7-52.
  • Remove Wedge Gauge J-7148-2 and Gauge J-7148-1. Insert the .053 end of the feeler gauge between the stop and center ear of the operating lever and repeat the operation just described, using the same reduced line pressure. Again, press against the exhaust valve core seal seat, using the same pressure as the first time. The valve should seal completely and no air noise should be heard. See Figure 7-53.
  • 1958 Buick Height Valve Core Setting View

    1958 Buick Height Valve Core Setting View

  • If air leakage was heard during the .053 test, bend the upper ear of the operating lever toward the valve core seat, but only slightly. (When bending the ear, do not remove the two gauges.) See Figure 7-54.
  • 1958 Buick Height Valve - Setting Exhaust Valve

    1958 Buick Height Valve – Setting Exhaust Valve

    Use the screwdriver or other suitable tool and once more press in to seal the core seat. If the bending performed was sufficient, no air leakage should be heard. If leakage is still heard, then the upper ear was not moved enough. If no leakage is heard, remove Wedge Gauge J-7148-2 and Gauge J-7148-1 and repeat Step (2) using the .049 end of the gauge. A slight amount of leakage should be heard. See Figure 7-54.

  • Remove both gauges and reverse their positions. Place .049 end of the feeler gauge between the side of the lever stop nearest to the valve cores and the middle ear of the operating lever and the wedge gauge on the opposite side. See Figure 7-55.
  • 1958 Buick Height Valve - Checking Intake Valve

    1958 Buick Height Valve – Checking Intake Valve

  • Remove the air hose, J-7143, from the air return fitting and install in the air supply (inlet) fitting. Increase the line pressure to 50-80 psi.
  • A slight amount of air leakage should be heard. If not, use a screwdriver or other suitable tool and bend the lower ear toward the intake valve core until some leakage is heard. See Figure 7-56.
  • 1958 Buick Height Valve - Setting Intake Valve

    1958 Buick Height Valve – Setting Intake Valve

  • Remove both gauges and place the .053 end of Gauge J-7148-1 into the same location and install the wedge gauge. NO air leakage should be heard. If air leakage does exist, bend the lower ear away from the valve core just enough to stop all air leakage. See Figure 7-57.
  • 1958 Buick Height Valve - Checking Intake Valve View

    1958 Buick Height Valve – Checking Intake Valve View

    Recheck using .049 end of gauge if additional bending was necessary.

  • Shut off the air line pressure and remove the hose from the height valve.
  • Install the dashpot into the valve body being sure to engage the groove in the dashpot shaft in the slot of the center ear of the operating lever.
  • Slide the dashpot retainer plate between the dashpot bracket and body. The stop ears on the retainer plate should be to the rear of the dashpot. Install the two retainer plate screws. Push the retainer plate and dashpot as far forward as possible before tightening the two screws.
  • Install a new cover O-ring into the groove in the valve body and install the cover. Tighten all four screws.
  • Connect hose, J-7143, to the air spring fitting and regulate air line pressure to 80-100 psi. Submerge the height control valve under water and check for leaks.
  • Install the height valve.
  • Manual Override Valve

    1. Disassembly
    • Remove lever spring from the bracket and manual lever.
    • Remove dust boot and 3 screws retaining bowden control wire bracket. Remove bracket. See Figure 7-58.
    1958 Buick Manual Override Valve (Exploded View)

    1958 Buick Manual Override Valve (Exploded View)

  • Remove the 4th screw at pressure regulator housing and remove housing with regulator adjusting screw. Measure and record the distance that screw extends from housing. Remove screw.
  • If the regulator spring and piston did not come out with the housing, reach into cavity and remove spring and piston.
  • Remove regulator diaphragm from within the cavity. See Figure 7-58.
  • Remove the air inlet plug and O-ring from bottom of valve. Do not lose filter, which should be in the plug.
  • Use tool J-7085 to turn valve stem which is in cavity above the plug. Hold valve stem retainer which is in upper cavity below the diaphragm by exerting a strong finger pressure on the valve. Turn stem counterclockwise to disassemble from retainer. Remove retainer and retainer spring from upper cavity and the stem from below. See Figure 7-58.
  • Remove plug and O-ring at return flow control valve (exhaust) end of override valve.
  • Remove air return spring, blow-off valve, plate and O-ring. See Figure 7-58.
  • Remove manual lever set screw at bottom of manual lever and remove lever from cam shaft.
  • Remove snap ring from valve body with Truarc #1 pliers. Then pull cam and O-ring from body.
  • Remove plunger from valve body.
    1. Assembly
    • Inspect all parts and clean with a suitable solvent which is not harmful to rubber. Blow dry with a low pressure. The seal on the valve stem is very critical as are other parts. Therefore, replace any doubtful parts.
    • Insert plunger into valve body with groove located to receive cam.
    • Replace O-ring on cam and install cam with pin on the end matching up with groove in plunger. Use Dow Corning 4-X on O-ring. Flat side of cam shaft should be up. See Figure 7-58.
    • Install snap ring, using Truarc #1 pliers. Install manual lever on cam. Secure lever with set screw.
    • Replace both O-rings at Return Flow Control Valve Assy. Install one O-ring into body, then plate, and then other O-ring.
    • Install air return spring into plug and plunger into spring. See Figure 7-58.
    • Install plug assembly into valve body and tighten.
    • Install valve stem into lower cavity of body and retainer spring and retainer into upper cavity. Place tool J-7085 over stem and turn clockwise while holding stem retainer stationary. Tighten securely.
    • Install inlet plug and filter, using a new O-ring on plug. Tighten plug.
    • Install diaphragm down into upper cavity of body.
    • Install adjusting screw into housing. Allow screw to extend out at top of housing the same distance as was measured before re­ moving screw. See sub. par. 1 (c) .
    • Position regulator spring into housing against adjusting screw.
    • Install piston over regulator spring.
    • Install housing assembly and bracket on valve body and install 4 screws. Tighten securely.
    • Install return spring on bracket and manual lever.
    • Install dust boot over housing.

    NOTE: After installing manual override valve on car, it must be adjusted so that correct supply line pressure is obtained. Refer to Par. 7 -11, Sub. Par. b.

    Rear Air Springs (plunger detached from diaphragm)

    1. Disassembly
    • Push seal up on plunger shaft so that spring pin in guide can be seen.
    • Use a drift pin of correct size and drive spring pin out of guide and plunger pilot. See Figure 7-59.
    1958 Buick Rear Air Spring Assembly

    1958 Buick Rear Air Spring Assembly

  • Remove seal from plunger shaft and pilot.
  • Guide bearing and plate are serviced as an assembly.
    1. Assembly
    • Clean and inspect all parts.
    • Reverse steps used in disassembly.
    • Lubricate top of the bearing with chassis lube before assembling.

    NOTE: On rear springs, the air dome , guide and diaphragm are replaceable as an assembly only. The plunger and pilot form another assembly.

    Front Air Springs

    1. Disassembly
    • Slide seal off pilot and guide.
    • Use a drift pin of correct size and drive spring pin out of guide and pilot. See Figure 7-60.
    1958 Buick Front Air Spring Assembly (Exploded View)

    1958 Buick Front Air Spring Assembly (Exploded View)

  • Remove bearing from guide.
    1. Assembly
    • Clean and inspect all parts.
    • Reverse steps used in disassembly.

    NOTE: On front springs, air dome, guide, diaphragm, plunger and plunger pilot are serviced as an assembly. If any one part of assembly should fail, complete assembly must be replaced.

     

    7-11 ADJUSTMENTS ON THE CAR

    Checking and Setting Trim Heights

    1. Check the operation of the height control valves by applying weight to each side of the rear bumper, one side at a time, and to the center of the front bumper. The car should raise back to normal trim height after weight has been added and should lower to the proper height after the weight has been removed.
    2. Check and correct tire pressures and inspect for an y binding anywhere in the suspension system. Correct if necessary.
    3. Check shock absorber action and replace if necessary.
    4. Drive the car on a front end machine. To check front trim heights, check the distance between the top of the compression bumper and lower side of the frame side rail, directly above the compression bumper on each side. Distance should measure 1 1/4″, plus or minus 1/4″, on all models. See Figure 7-61.
    1958 Buick Front Trim Height

    1958 Buick Front Trim Height

  • If trim settings are not correct, loosen the two nuts and bolts at the link clamp-bracket on the front stabilizer bar. Rotate the clamp­ bracket in the correct direction and tighten both nuts and bolts. Recheck trim height settings once more.
  • NOTE: If the trim height varies between each side at the front, it could be due to a variation between each rear height valve trim setting. If such is the case, after correcting trim height at the front as close as possible, correct t rim heights at each rear height valve and then recheck the front.

    1. To check rear trim heights, check the distance between the tip on the bottom of the rear compression bumper and the strut rod-shock absorber bracket directly below the compression bumper. Distance should measure 1 5/8″, plus or minus 1/4″, on all models except the 49 and 69. The distance should measure 1 1/4,” on the 49 and 69 models. Repeat check on the other side. See Figure 7-62.
    1958 Buick Rear Trim Height

    1958 Buick Rear Trim Height

  • If trim heights are not correct, loosen the two bracket-to-height valve screws, on the front side of each bracket, and rotate the height valve in the correct direction. The holes in the brackets are elongated to allow for valve rotation.
  • Checking and Setting Supply Line Pressure

    1. Bring air tank pressure up to 200 psi.
    2. Disconnect the air return line on the top of the manual override valve and install hose J-7143. See Figure 7-63.
    1958 Buick Manual Override Valve Overview

    1958 Buick Manual Override Valve Overview

  • Pull the manual lift knob, which is inside the car at the right dash panel, to put the car into the lift position.
  • Press Gauge J-6840 on the end of Hose J-7143 and take a reading. Remove the gauge.
  • If pressure is more than 125 psi, remove the boot from the override valve and turn the adjusting screw out (counterclockwise).
  • Depress the Schrader core in the end of the hose for two-three seconds and then take another gauge reading.
  • If the reading is still too high, repeat the procedure until correct reading is obtained. If valve cannot be adjusted, remove the valve and disassemble.
  • If the pressure is less than 125 psi, turn the pressure adjusting screw in (clockwise) . Depress the Schrader core for two-three seconds and then take a gauge reading. Repeat the procedure until the correct reading is obtained.
  • If the correct reading cannot be obtained, remove the override valve and disassemble.
  • NOTE: Any time an override valve is to be disassembled, measure the height of the pressure adjusting screw that extends out of the housing. Then after assembling, position the screw at the same height and follow the procedure for checking and setting supply line pressure.

    1. Push the manual lift knob all the way in to lower the car to normal trim height.
    2. Depress the Schrader core in the hose to exhaust all air from the hose and then remove the hose.
    3. Connect the air return line at the over­ ride valve using a new O-ring, and pull the manual lift knob to put the car into the lift position. Use bubble solution at the fitting connection to check for leaks. Push knob in to lower car.

     

    7-12 NEW CAR PRE-DELIVERY INSPECTION

    1. Start the engine and bring the pressure in the air tank to 150 psi. Run the engine at 1500 RPM for 2 1/2 minutes and again check pressure. Pressure should be a minimum of 200 psi. If not, see Diagnosis Section.
    2. Pull the lift control knob to raise car to the lift position. Bring the pressure in the air tank to 200 psi. Take a temperature reading a few inches away from the air tank and mark this reading down. Allow the car to stand over­ night and take another pressure and temperature reading the following morning.
      1. If the temperature drops only 10° F or less between evening and the next morning, then pressure should not be less than 170 psi. (30 psi drop allowed for the initial 10° F drop.)
      2. If the temperature lowers more than 10° F, then the pressure drop should not be more than 30 psi, plus two pounds for every 10° F drop after the initial 10° F drop.
    1958 Buick Temperature Pressure Adjustment

    1958 Buick Temperature Pressure Adjustment

    For the first 10° drop in temperature, 30 psi pressure reduction is allowed. Since temperature has lowered an additional 20° (to 50°), then an additional 40 psi pressure reduction (to 130 psi) is also allowed. However, our Air­Poise only lowered to 140 psi. Therefore, system is satisfactory. Use temperature drop-minimum pressure chart, Figure 7-64, to get readings when in doubt.

    1958 Buick Tank Pressure

    1958 Buick Tank Pressure

    1. If pressure reduction was too great, see section covering leak checking in diagnosis section.
    2. With air tank pressure of 200 psi and engine running, apply weight (minimum of 100 pounds) to each side of the rear bumper, one side at a time, and to the center of the front bumper. Observe whether car raises to normal trim height after weight has been added and whether car lowers to proper height after weight has been removed. If height valves do not function properly, see Diagnosis Section.
    3. Check the trim height. It must be 1 1/4″ at the front on all models and 1 5/8″ at the rear on all models except Estate Wagons. On Estate Wagons, trim height is 1 1/4″ at the rear. If trim heights are not correct, refer to Par. 7-11, sub. par. a.

    NOTE: In cases where the evening temperature reading is colder than the morning reading, then reverse the use of the chart. Add two pounds for every 1° F increase in temperature.

     

    7-13 JACK INSTRUCTIONS

    CAUTION: On Air-Poise equipped cars, the manual lift knob must be pulled out so car is in rebound position before using bumper jack to raise car. After jacking operation is completed, manual lift knob must b e pushed back firmly into the normal opera ting position before car is driven.

    1958 Buick Jack Instructions

    1958 Buick Jack Instructions