chapter 64 suspension system service · the entire strut assembly. occasionally a strut cartridge...

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INTRODUCTIONEmphasis in this chapter is on the diagnosis and ser-vice of suspension system parts. The reader will become familiar with commonly performed chassis diagnosis and repair procedures. When suspension parts are in good condition and properly aligned, they are sub-jected to two forces: the weight of the car on the springs and the force of the road on the tires (Figure 64.1).

Suspension parts take a large amount of abuse as the car is regularly driven over potholes, speed bumps, and concrete expansion joints. Forces are transmitted through the suspension parts, causing wear over time (Figure 64.2).

DIAGNOSING SUSPENSION SYSTEM PROBLEMS

When diagnosing a suspension problem, carefully question a customer about the symptoms. Suspension system problems usually come to light when the cus-tomer complains of a noise such as a clunk or squeak, vibration, steering pull, or tire wear. All of the suspen-sion system parts depend on each other. The rest of the system is affected when one part becomes worn.

Wheel alignment settings can change when a sus-pension component wears. Bushing wear can cause suspension parts to change position. This can cause a

axial movementdominant end

radial movementwear indicator ball joint

KEY TERMS

CHAPTER 64

OBJECTIVESUpon completion of this chapter, you should be able to:■ Diagnose suspension system problems.■ Service suspension system components.■ Describe suspension system repairs.■ Replace Macpherson struts.■ Replace suspension bushings.

Suspension System Service

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Figure 64.2 Locations of wear.

Figure 64.1 The weight of the car and the force of the road act on the suspension system.

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1200 CHAPTER 64

bushings. As a vehicle accumulates mileage and the suspension loosens up, some owners choose to replace the shocks in order to stiffen the ride. Shocks should be checked to see that they still provide good control.

TESTING A SHOCKA preliminary shock test with the car on the ground is the bounce test. Using a clean shop towel, push down hard two or three times on the fender at each cor-ner of the car. The spring should oscillate only about 1.5 cycles and then settle. Be aware that a shock that is bounce tested could still be bad. This only tests the very lowest piston speed; it does not fully indicate the condition of the shock.

NOTE: The bounce test only checks the first stage of shock absorber operation. A failure in the second or third stage valves would not be evident from this test. Therefore, if the shock passes the bounce test, it still might be defective.

The bounce test and looking for cupped tires are worst case, last resort types of evaluation.

Evaluating worn shocks is best done by driving the vehicle over a variety of roads.

Shocks do not often fail at the same rate. Usually one shock has a problem, requiring the replacement of both of them at that end of the vehicle.

When there is a noise complaint its location can often be determined during the bounce test. The sound of the fl uid being forced through the valves in the shock is normal.

Perform a visual inspection of the shock:■ Inspect the condition of the shock mounts and

rubber cushions.■ Look to see if any fluid has leaked out of the

shock, indicating a bad seal. Fluid cannot be replenished and the shock will have to be replaced. It is normal for a slight amount of moisture to be on the seal (Figure 64.4).

car to pull to one side either all the time or just when braking.

As a vehicle ages, spring sag is a normal condi-tion that occurs. The springs lose their ability to keep the vehicle at the correct ride height. As the springs weaken and the vehicle sits closer to the ground, wheel alignment angles change and abnormal tire wear can result. This is because the camber angle will change on most cars when the ride height drops (Figure 64.3). Ride height measurement is covered in Chapter 68.

Check all ball joints and bushings for looseness. Check rubber bushings and the sway bar links for wear or cracking.

SHOCK ABSORBER SERVICEShock absorbers can be functioning poorly before obvi-ous signs of failure appear, such as tire cupping or exces-sive front-end fl oat. Inadequate shock absorbers can cause excessive body motion, road wander (especially in wind), poor adhesion of the tire to the surface of rough roads, a harsh ride, suspension bottoming, and poor braking. A bad shock absorber on one corner of the vehi-cle can cause the entire vehicle to feel strange.

A defective shock absorber can cause a tire to “hop.” Feel the tire tread around the total circumfer-ence of the tire. When there is a scalloped or gouged wear pattern around the tire tread, look for a bad shock absorber. Tires that are unbalanced or out-of-round can also be a contributing factor.

A shock absorber can be defective because it is leaking or physically damaged. When one damaged shock is found, both shocks on that end of the vehicle (front or rear) are replaced. A leaking shock can be the result of a defective seal or from lowering a vehicle too far. A damaged piston rod on a Macpherson strut causes a leak as well. This can result from holding the rod with pliers during installation of the top nut.

Some original equipment (OE) shock absorbers are of high quality and still work well after 50,000 miles. OE shock absorbers are designed to give a soft, satisfactory ride when used with tight, new suspension

Originalcamberangle

Wear and spring sag

Figure 64.3 The camber angle will go toward negative on most cars when the ride height drops.

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Figure 64.4 A slight amount of oil on the seal is normal.However, the body of the shock should not be wet.

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Suspension System Service 1201

■ If the outside of the shock body is damaged, replace both shocks.

■ If rubber bump stops show signs of contact, a shock could be damaged or the vehicle might have been lowered or raised excessively.

When the operation of the shock is in question, it can be unbolted from its lower mount. Then the shock can be moved through its normal range of motion while checking that it moves with equal resistance. If the shock skips or slips as its direction of motion is changed, it is defective.

Shocks sometimes limit spring travel. When the shock is removed, the control arm can drop quickly downward in response to spring pressure. On some coil spring cars, if the shocks are removed, the spring can fall out. If the shocks are to be replaced, the car should be raised on a hoist that supports the wheels. If this is not possible, support the axle with a high lift stand while removing the shock (Figure 64.5).

The top of a shock absorber is often hidden under a rear seat or within the trunk (Figure 64.6). A special tool is available to help with shock absorber removal and installation. One end prevents the shock rod from turning while loosening or tightening the retain-ing nut (Figure 64.7). The other end of the tool is installed through the hole in the seat well or trunk and threaded onto the end of the shock rod to assist in pull-ing it into place (Figure 64.8). This is not necessary on gas shocks because they expand to their full length.

Shock MountsCheck the mounts at each end of the shock to see that they are holding the shock securely to the vehicle. It is relatively common for a shock absorber to become

Shockabsorber

Figure 64.7 A special shock tool. This end of the tool is used to hold the shock rod while loosening or tightening the retaining nut.

Figure 64.6 The top of this shock absorber is located under the fl oor mat in the trunk.

Shockabsorber

Safetystand

Figure 64.5 Be sure to support the axle before removing a shock.

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Figure 64.8 This end of the tool is installed through the hole in the trunk and threaded onto the end of the shock rod to assist in pulling it through the hole in the trunk.

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1202 CHAPTER 64

Gas ShocksA gas-fi lled shock absorber will expand to its fully extended position if not restrained. There is a band around a new gas shock to hold it compressed while it is in the box. This is cut when installing the shock in the vehicle. If a gas shock has lost its gas charge, it will no longer expand on its own. It may still have oil in it, but the gas charge will no longer be there to prevent foaming when the oil becomes heated.

MACPHERSON STRUT SERVICEMany vehicles have Macpherson strut suspensions. When a Macpherson strut shock fails, there are two repair procedures. The most common repair is to replace the entire strut assembly. Occasionally a strut cartridge is installed into the original shock housing In either repair, the entire strut assembly is removed from the car (Figure 64.11). First, mark one of the bolts and its location at the top of the strut tower (Figure 64.12). The top of the strut is easy to remove.

The center nut must not be removed from the top of the strut before the strut assembly is removed from the vehicle. This would allow the spring to

be decompressed during strut removal.

SAFETYNOTE

SAFETYNOTE

Some struts are easily removed at the bottom by removing two bolts that fasten the strut to the spindle support (Figure 64.13). Occasionally a brake line will need to be removed from a caliper; brake bleeding will be required following the strut replacement. Some-times one of the two bolts has a slot that allows the camber adjustment during a wheel alignment. If the vehicle has this adjustment feature, be sure to mark the location of the bolt so it can be replaced in the same position.

loose. Shocks are mounted to the chassis with rubber cushions. Shock mounts for passenger cars are usually the single stud (bayonet) type or the ring mounting type. Some of the ring mountings have a cross-pin, stud, or bolt pressed into them (Figure 64.9).

Rubber cushions allow a shock absorber to have some fl exibility in its mount. On some single stud-type shocks, the tightness of the nut can determine how well the shock cushion functions. Some stud mount nuts are torqued against a shoulder on the stud. Others are tightened only until the rubber bulges out until it is even with the end of its metal retainer (Figure 64.10).

Air ShocksAn air shock can sometimes fail when it gets a hole in its rubber bladder. Sometimes the rubber will rot if oil leaks onto it. If the shock is installed in a tight location, the rubber can rub on suspension parts when the air bladder is infl ated. Check for leaks using soapy water. Rub the solution over the lines, fi ttings, and bladder while the shocks are infl ated. Look for bubbles, which would indicate a leak.

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Figure 64.11 The entire strut assembly is removed from the car.

Figure 64.9 Different shock mounts.

Threaded stud

Ring

Cross-pin

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Figure 64.10 Tighten the nut until the cushions bulge almost to the outer edge of the retainers.

Retainer

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Hammering on a pinch bolt can dam-age both the bolt and the ball joint. If

the pinch bolt does not come out easily, pry on the lower control arm to release any

tension that might be there. A compressed spring can be dangerous. Raise the vehicle by the frame and allow the spring to extend as far as pos-sible to unload it prior to removing the strut.

CAUTIONCAUTION

A spring compressor is used to compress the coil spring (Figure 64.15). With the spring compressed, the nut at the top of the strut can be removed from the strut rod. Once the nut has been removed, the parts can be disassembled from the strut.

Figure 64.14 A pinch bolt holds the steering knuckle to this ball joint.

Figure 64.13 Remove these bolts to remove the spindle support and caliper from the strut. Remove the brake hose only if it is in the way.

Disconnecting and removing the bottom part of the strut is sometimes more diffi cult when the lower ball joint needs to be disconnected from the spindle support/steering knuckle. This allows the lower con-trol arm to be pried down so the strut can be removed. Some lower ball joints have a pinch bolt that holds the ball joint (Figure 64.14). Others will have a cotter pin and castle nut that will need to be removed.

Pinchbolt

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Figure 64.15 A Macpherson strut compressor, sometimes called a “clamshell.”

Figure 64.12 Prior to loosening the strut-to-chassis bolts, make an alignment mark on one strut bolt and the chassis.

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1204 CHAPTER 64

INSTALL THE COIL SPRINGInstall the coil spring and tighten the locknut. Be sure both ends of the spring are correctly seated before removing the compressor (Figure 64.17).

Do not use an impact wrench to tighten the locknut. This can spin the

piston rod and damage the new seal.

CAUTIONCAUTION

REINSTALL THE STRUT ASSEMBLYReinstall the strut assembly on the car in the same posi-tion it was in before. Depending on the suspension sys-tem design, a wheel alignment might be needed after a strut replacement. If the brake caliper hose was discon-nected, brakes will need to be bled as well.

SUSPENSION BUSHING SERVICEDamaged or worn suspension bushings can change wheel alignment settings (Figure 64.18). Bushings are made of synthetic rubber. They insulate suspension parts from noise and road shock. Upper control arm bushings are especially prone to heat damage because of their close proximity to engine exhaust manifolds. Driving on bumpy roads can also result in heat and fatigue of the bushing material.

Bushings should not be lubricated. Lubricants attract dirt and can sometimes damage the bushing material. Rubber lubricant (the kind used to aid in mounting tires) can be used to help quiet a squeaky, hardened bushing, but the fi x is only temporary.

Inspect suspension bushings for deterioration and splits in the rubber (Figure 64.19). See if the bushing is off-center. Bushings are sometimes located where

A tight nut can be removed using an impact wrench, squeezing the trigger rapidly

to produce short bursts of power. Avoid spin-ning the shaft.

SHOPTIPSHOPTIP

Be careful with the compressed spring. Dropping it can cause it to dislodge from the spring compressor with dan-gerous results.

SAFETYNOTE

SAFETYNOTE

Replacing a Strut CartridgeSome struts can be serviced with a shock cartridge (Figure 64.16). The nut at the top of the strut is either a conventional hex nut or one that requires a special spanner wrench. Sometimes an OE strut is not enclosed in a cartridge so there will be fl uid that needs to be poured out of the strut housing. Add new lightweight oil, such as automatic transmission fl uid (ATF), to help conduct heat between the new cartridge and the outside of the strut housing. The level should almost reach the top of the strut tube with the new cartridge in place. Center the strut cartridge in the strut body before installing the locknut.

INSPECT THE UPPER STRUT BEARINGInspect the condition of the upper strut bearing while the strut assembly is disassembled. A questionable bearing can easily be replaced at this time.

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Figure 64.17 The end of the spring is aligned with its seat.

Springseatshere

Figure 64.16 A replacement cartridge is sometimes installed in the old strut.

Replacementshock cartridge

Shock absorber assembly

Piston

rod

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Bushings are removed by pressing or driving them out. It is important that the control arm holes not be damaged by the process. If an air chisel is used, be sure that the chisel bit is wide and dull. If it is sharp, it will cut the bushing rather than push it out.

Figure 64.20 shows removal of a bushing using a bushing puller. The puller kit also includes adapters for bushing installation (Figure 64.21).

NOTE: Tighten bolts or nuts that hold bushings in place only when the suspension is the position where it normally sits at rest.

STRUT ROD BUSHING SERVICERefer to Figure 63.13 for the relationship between the strut rod, lower control arm, and bushing. When replacing a strut rod bushing, the nut is removed. This will allow the lower control arm to move fore or aft. Next remove the fasteners that hold the strut rod to the control arm and slide the strut rod out of the bushing. Most bushings have a center spacer that will only allow the bushing to be compressed a certain amount during reinstallation when the strut rod nut is tightened.

STABILIZER BAR SERVICEInspect the bushings at each end of the stabilizer bar (Figure 64.22). Replace any bushings that are cracked, worn, or weathered. Remember to tighten any newly installed bushings while the weight of the vehicle is supported.

a visual inspection can be diffi cult. A fl ashlight and mirror can be helpful here.

Push on the fenders of the vehicle while listening for noise.

To inspect bushings for looseness, use a prybar to see if the control arm can be moved.

Figure 64.19 Inspect suspension bushings.

Polishedareas indicatemovement

Off-center

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Figure 64.20 Control arm bushing removal with a puller.

Control arm

Spacer

Bushingremoval tool

Distortion ormovement here...

...can cause undesirable movement here

Figure 64.18 Defective bushings can change alignment settings.

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Figure 64.21 Control arm bushing installation with a puller.

Control arm

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1206 CHAPTER 64

Cuts or tears in the boot will allow water and dirt into the joint, causing it to wear. Feel around the outside of the boot, looking for tears. If the boot is torn, the joint will probably fail soon and should be replaced. Inspect the control arm near the joint for signs of rust or cracks.

Manufacturers list specifi cation limits for ball joint movement. Always check the specifi cations and be sure that the proper procedure is followed. Vertical or axial movement is usually specifi ed. Some manufac-turers specify horizontal or radial movement as well (Figure 64.24).

A load-carrying ball joint usually has some move-ment when unloaded. Sometimes unnecessary replace-ment of good ball joints had been done by incompetent repair businesses. Therefore, some states now require measurement and documentation of the amount of clearance found on a worn ball joint before it can be replaced. Most load-carrying ball joints have a wear

When replacing stabilizer bar bush-ings, be sure that both front wheels are

either on the ground or in the air. Oth-erwise, the sway bar will be spring loaded.

With one wheel jacked up, removal of the nut on the top of the stabilizer link could result in a serious injury.

CAUTIONCAUTION

SPINDLE SERVICEReplace a steering knuckle or spindle that is damaged. If a wheel bearing fails, it can wear or heat the spindle. This changes the metallurgy of the spindle and it must be replaced.

A front-wheel bearing failed on a 1965 Mustang. There was wear on the spindle that the technician failed to notice. He replaced the wheel bearing and returned

the car to the customer. Several months later, the cus-tomer’s daughter was driving the car when she drove over a small pothole in the road. The spindle broke off just behind the area where the old bearing had burned (Figure 64.23). She was not traveling fast and, luck-ily, was not hurt when the front wheel fell off the car.

CASEHISTORY

CASEHISTORY

Damage from a collision will be evident during the steering axis inclination (SAI) alignment angle check.

BALL JOINT SERVICEBall joints are relatively trouble-free, but sometimes they wear out. The ball joint has a sealed rubber boot fi lled with grease. If the joint has a grease fi tting, a small bleed hole in the boot allows for grease move-ment during lubrication.

Figure 64.23 This spindle broke after a burned wheel bear-ing was replaced.

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Figure 64.22 Inspect stabilizer bushings.

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Bushingwalkingout ofbracket

Bushingwallowed outLarge crack

and splits

Loose ormissingcomponents

Large cracks orsplits in stabilizerlink bushings



testing. Try to move the tire back and forth while looking for movement. For this test to be accurate, wheel bearing clearance cannot allow the wheel to move. Recommendations for most follower ball joints call for replacement if there is “any perceptible move-ment” in the joint. Always check the manufacturer’s specifi cations.

■ A quick way to eliminate wheel bearing clearance from the measurement

is to apply the brakes during the test. When a helper is not available, brakes can be applied using a pedal depressor.

■ To measure ball joint clearance without a dial indicator, measure the length of the ball joint with a caliper and then measure it again when the joint has been unloaded.

SHOPTIPSHOPTIP

Wear Indicator Ball JointsSome ball joints have a built-in wear indicator. The most common type has a shoulder that sticks out of the bottom of the joint about 0.050" when it is new ( Figure 64.27). If the ball joint has worn, this shoulder

limit of 0.060" of vertical movement, although there are some ball joints that can have as much as 0.200" movement and still be within specifi ed limits.

Before checking ball joint wear, determine whether the ball joint is a load carrier or follower (see Figure 63.40). This is important when testing ball joints for wear because the load-carrying joint must be unloaded before testing. Load-carrying ball joints are either ten-sion or compression types (see Figure 63.41). Tension-loaded ball joints are more common.■ The ball joint on the control arm with the spring

attached is the load carrier.■ The ball joint on a Macpherson strut suspension is

the follower joint and, therefore, carries no load.

MEASURING BALL JOINT WEARCheck the manufacturer’s recommended procedures before checking ball joints. For an accurate wear check, the ball joint must not support the weight of the vehi-cle. In some SLA suspension systems, the spring is located above the upper control arm.

Figure 64.25 shows how to unload the ball joint when the spring is on the upper control arm. Figure 64.26 shows how to unload the joint when the spring is on the lower control arm. Prying between the tire and ground will show any clearance.

A follower ball joint holds the steering knuckle in the correct position and allows it to pivot dur-ing bumps and turns. The follower joint should be checked while the loaded ball joint is unloaded for

Figure 64.25 Unloading a ball joint to check for wear when the spring is above the upper control arm.

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Spring aboveupper control arm

Followerball jointSupport

bar

Load-carryingball joint

Figure 64.26 Unloading a ball joint to check for wear when the spring is on the lower control arm.

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Follower ball joint

Spring onlower controlarm

Load-carryingball joint

Axial check

Radial check

Figure 64.24 Ball joint checks.

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1208 CHAPTER 64

will recede into the ball joint housing. When it is fl ush, the ball joint should be replaced. A wear indicator ball joint must be loaded and at normal ride height to read the indicator.

SEPARATING TAPERED CONNECTIONSThe ball joint is connected to the steering knuckle with a tapered connection, called a steering taper (Figure 64.28). This type of joint is also used in other steering connections. Loosening the tapered connection on a ball joint can be accomplished using a large hammer.

First, remove the cotter pin from the ball joint nut and loosen the nut several turns.■ If you understand the relationship between the

parts, you will be able to make the spring pressure work for you. Position the vehicle so that the coil spring is pushing the control arm away from the ball joint. This will either require the vehicle to be lifted or allow its weight to rest on the wheels.

Figure 64.27 Checking a wear indicator ball joint.

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Worn Good

Wearsurfaces

Sinteredironbearing

Wearindicator

Preload0.050"

Figure 64.28 A ball joint taper.

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Control arm

Steeringknuckle

Ball joint

Taper

Castlenut

Cotterpin

■ Use a hammer to pound sharply on the steering knuckle at the outside of the taper, with another hammer held against the back side. This will deform the taper and spring pressure will help to separate the ball joint from the steering knuckle.

NOTE: A pickle fork (see Figure 66.8) will probably ruin the rubber seal on the ball joint. If the ball joints are not going to be replaced, this will be a costly subtraction from the profit of the job.

REPLACING A BALL JOINTThere are several ways that ball joints are held in place. Figure 64.29 shows three of the most common meth-ods. Some OE ball joints are fastened to the control arm with rivets. They must be removed in order to remove the ball joint (Figure 64.30). First, drill a small hole about halfway into the rivet. Then use a larger drill bit to drill into the rivet until the rivet head falls off. Bolts and nuts are used to hold the replacement joint in place.

Figure 64.29 Three common ball joint retaining methods.

Pressed-fit Rivet or bolt

Threaded

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Figure 64.30 Replacing a riveted ball joint.

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Incorrect ride height affects wheel alignment angles, camber, toe, SAI, and scrub radius. A short-and-long-arm (SLA) suspension system is designed so the vehicle rides at a height that minimizes changes in tread width. When sagged springs cause the suspen-sion system to drop, the upper control arm will move to a different place in its normal arc of travel. This means that there will be even more camber change during bumps (Figure 64.32). Tires will wear faster and handling is affected.

A vehicle that is too low cannot be aligned prop-erly, so this test should be done before attempting a wheel alignment. The ride height check is covered in Chapter 68.

ADJUSTING SPRING HEIGHTThe vehicle’s correct ride height needs to be restored prior to an alignment. When coil springs have sagged beyond specifi cations, they are replaced. A few vehi-cles use torsion bar springs that allow for spring height to be adjusted by tightening a screw against a bracket mounted on one of the torsion bar ends.

Air shocks or shock absorbers with coil springs around them are designed to be used only for tempo-rary overload conditions. The weight of the vehicle will rest on the shock mounts instead of the spring seat. Shock mounts are not designed to continually support the vehicle.

COIL SPRING REPLACEMENTSprings are replaced in front or rear pairs. Some after-market springs have a part number stamped on the end of the coil. OE springs are often tagged with a part number wrapped to one of the coils. The tag might be missing or unreadable. Replacement springs must be of the same kind as the original ones. Coil springs have different shaped ends. Square-ended coils can be tapered or untapered. Full wire spring ends can also be cut off squarely; this is called tangential. Figure 64.33 shows different spring ends.

Some ball joints are pressed or threaded into the hole in the control arm. A special press set can be used to remove and replace pressed-fi t ball joints while the control arm is in the vehicle. Figure 64.31 shows this process. Some pressed-fi t ball joints have a spot weld that holds them in place. This must be carefully removed. When a replacement ball joint is installed, a snap ring often takes the place of the weld.

When a control arm has been removed from a vehicle, a pressed-fi t ball joint can be removed using a standard hydraulic press.

NOTE: When installing a new ball joint, be sure the grease release hole in the rubber boot is aimed away from the brakes.

COIL SPRING SERVICEA coil spring will rarely break unless it has been con-stantly overloaded or it has a stress raiser in its surface from a nick, corrosion, or defect. The weight of the car causes the coil spring to lose some of its tension as the car grows older. This lowers the ride height. A ride height check can be performed to see if the height of the car conforms to specifi cations.

A = camber angle change

Figure 64.32 The position of the control arm changes in its arc due to spring sag.

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Lower control arm

Pressing tool

(a)

Lower control arm

Pressing tool

(b)

Figure 64.31 (a) Ball joint removal. (b) Installing a pressed-in ball joint in the lower control arm.

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1210 CHAPTER 64

Use two clips to hold the spring compressed (Figure 64.36). Spring clips are either short or long; use the one that fi ts best. Short clips are used to hold four rungs of the spring. Long clips are used to clip fi ve rungs. Use two clips positioned side by side on the same spring rungs. Position the clips as low as possible on the inboard side of the spring.

Pry down on the lower control arm and pry the coil spring from its place. Mark the locations of the clips. Then use a coil spring compressor to compress the spring and remove the clips.

Never compress the spring far enough for the coils to stack against each other.

SAFETYNOTE

SAFETYNOTE

Aftermarket regular duty coil springs are similar to OE springs but are sometimes designed with different characteristics. See Chapter 63 for more information on springs.

SLA COIL SPRING REPLACEMENTRemoving and replacing springs on most passenger cars is done using a coil spring compressor. A spring that is installed in a vehicle is compressed; when it is fully extended, it is much longer. Before removing a spring, remove the wheel, shock absorber, and stabilizer links. Disconnect the outer tie rod from the steering arm.

When replacing a coil spring, only the lower ball joint needs to be disconnected from the lower control arm. The upper ball joint can usually remain in place in the upper control arm, which is moved out of the way along with the steering knuckle.

Sometimes both the upper and lower ball joint tapers must be separated to be able to get the disc brake splash shield and spindle to clear the lower con-trol arm. Remove the cotter pin from the ball joint nut and back the nut off several turns.

When using the special ball joint press to loosen a taper connection, unload the ball joint with a fl oor jack. For maximum leverage, position the jack so it is as close to the outer ball joint as possible. A piece of plywood will help get more leverage and keep the jack level.

To jack up the control arm, reach across from the opposite side of the vehicle (Figure 64.34). This will allow the jack to roll toward the inside of the vehicle

as the control arm is lowered, releasing spring pressure.

SAFETYNOTE

SAFETYNOTE

Raise the jack to compress the spring until the vehicle begins to lift. Remove the lower ball joint nut and lift the steering knuckle assembly away from the ball joint stud. Support it out of the way. A coil spring compressor can also be used to keep the spring com-pressed while repairs are performed to the spindle or upper control arm (Figure 64.35).

Figure 64.33 Different types of spring ends.

Figure 64.34 The correct way to use a jack when doing SLA coil spring work.

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Square end(tapered)

Square end(untapered)

Tangential

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Figure 64.35 A spring compressing tool installed on a spring in a short-and-long arm suspension system.

Lowercontrol arm

Spring compressor ©

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Lay the old spring next to the new spring and align the dominant ends (Figure 64.37). The domi-nant end is the end that aligns in the coil spring seat in the frame or lower control arm. Mark the new spring in the same location of the old spring. Compress the spring and install the spring clips (see Figure 64.36).

The spring will be bowed with the spring clips installed. During installation, this will make it easier to align the upper and lower spring seats. When there are insulators that fi t into the spring seats (Figure 64.38), tape them onto the spring to make installa-tion easier.

The spring seats must be accurately aligned during installation. Align the upper end fi rst. Then push the bottom of the spring into place. Be sure that the lower spring end fi ts into the pocket in the spring seat. Jack the control arm to compress the spring and install the ball joint stud in the tapered hole (Figure 64.39).

Cotter pin hole

Steering knuckle

Figure 64.39 Align the cotter pin hole and install the ball joint in the steering knuckle.

NOTES:■ Be sure to align the cotter pin hole so it is parallel to

the brake backing plate. Otherwise, it will be difficult to install the new cotter pin in the castle nut.

■ If the cotter pin hole does not line up, tighten until the next hole does. Do not back off on the nut to align the hole.

Torque the castle nut to specifi cations. After connect-ing the ball joint(s), remove the spring clips from the spring. A small prybar may be needed for this.

Complete the assembly of all of the components. Before lowering the wheels onto the ground, loosen the bolts that compress the control arm bushings. Drive the vehicle a short distance and jounce the sus-pension several times. Retorque all bushings to specifi -cations before doing a wheel alignment.

Torsion Bar Removal and ReplacementBefore a torsion bar can be removed, its adjusting bolt must be loosened (Figure 64.40). First, measure how far its adjusting bolt extends above the surface of the

Spring clips

Figure 64.36 Compress the spring and install the spring clips.

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Coil springlower seat insulator

Coil springupper seatinsulator

Figure 64.38 Insulators sometimes fi t into the spring seats.

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Old springNew spring

Dominant ends

Figure 64.37 Align the dominant ends of the old and new springs.

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1212 CHAPTER 64

disassemble the spring pack. Spring leaves are different lengths. Before disassembly, use a crayon to number the springs so they can be easily replaced in their original positions.

Removing leaf springs is easiest to do on a wheel contact lift with the vehicle frame supported by the lift’s air jack. If a wheel contact lift is not available, the job is performed with the vehicle on the ground. Raise the body of the vehicle and rest the frame on safety stands with the wheels just off the shop fl oor. Then disconnect the spring from one side at a time. When possible, leave the vehicle in the same position so the spring can easily be reinstalled.

NOTE: When positioning the spring be sure that the head of the center bolt fits into the hole or recess in the spring seat. This correctly positions the spring fore and aft.

WHEEL ALIGNMENTAfter completing suspension work, a wheel alignment is needed to reposition suspension components so that the car will be safe to drive and will go straight without unusual tire wear.

Remember to torque bolts that go through bush-ings only after the vehicle is resting on its tires.

ELECTRONIC SUSPENSION SERVICEElectronic suspension system problems are often related to mechanical failures, including leaks in the system. A leak can occur in a rubber spring bladder, or nylon tubing can be damaged.

Electrical failures can also occur in the air system. The length of time a compressor can run is limited to a few minutes in case of a solenoid malfunction. Com-pressor failures do, however, occur.

If the battery is being charged, the ignition switch must be in the “off” position if the air suspension switch is on. Otherwise damage to the compressor relay or motor could result.

Wiring connections are also a common source of problems. Sometimes simply disconnecting and recon-necting wiring connections will correct a problem.

Electronic failures will set a diagnostic trouble code (DTC) and cause an instrument panel light to fl ash or illuminate continuously. The source of an electronic problem can usually be traced using a scan tool to display any DTCs stored in computer memory. Many aftermarket scan tools have the ability to diag-nose the most probable electronic failures. However, manufacturer-specifi c scan tools are often best for diagnosing the most troublesome problems on specifi c makes of vehicles.

There are several sensors for electronic suspension systems (see Chapter 63). Service information contains detailed charts and diagrams for each manufacturer’s system. Figure 64.41 shows a typical list of DTCs for a programmed ride control (PRC) system.

bracket. This will save time when readjusting ride height after reinstallation. Be sure the wheels are lifted off the ground before attempting to loosen the adjusting bolt.

If the same torsion bar is to be reinstalled, mark its end and its adjusting arm prior to removal so it can be reinstalled in the same position.

Some SUVs with torsion bars have air suspension systems. To avoid injury,

disable the air suspension system before working on the system.

CAUTIONCAUTION

Before reinstalling a torsion bar, be sure it is going into the correct side of the vehicle. Torsion bars are direc-tional. They are marked left or right, as viewed from the driver’s seat.

After the torsion bar is installed, check and adjust ride height as needed (see Chapter 68).

Leaf Spring ServiceLeaf spring problems include broken leaves, spring sag, differences in ride height from side to side, squeaks, worn bushings, and broken center bolts. Bushings and shackles can be replaced without removing the spring from the vehicle.

When leaf springs have sagged, they are removed and sent to a facility where they can be “re-arced.” This reestablishes the original ride height.

Multiple leaf spring leaves have holes through their centers. A center bolt runs through the holes of all the springs, with the head of the bolt fi tting into an opening in the spring mount on the axle. The center bolt holds the position of the axle in relationship to the springs so the rear wheels can track behind the front wheels. Some-times the center bolt breaks. This can alter the position of the rear axle, changing vehicle tracking and alignment.

When insulators need to be replaced or there is a broken spring leaf, secure the spring with a C-clamp or in a large vise. Then remove the center bolt and

Torsion bar

Loosen here

Figure 64.40 Remove tension from the torsion bar adjusting bolt.

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To remove the actuator, squeeze the plastic retain-ers and lift the motor from the top of the strut (Figure 64.43). To test the actuator, turn the key to “on” while the actuator wiring is still connected. When the ride control switch is switched to either the fi rm or the soft position, the motor should rotate the control tube on the bottom of the actuator within a few seconds. If it rotates, the actuator is operating. If not, refer to the manufacturer’s instructions before testing the unit.

Be sure the leveling system is disabled before raising the vehicle on a lift,

jacking it up, or towing. Some systems stay on all the time; they are not activated

by the ignition switch. The ignition switch must be off, and the leveling system switch—often located in the trunk—must be turned off before lift-ing or towing the vehicle.

CAUTIONCAUTION

When raising a vehicle with an electronically con-trolled air suspension, most manufacturers recommend a frame-contact hoist. Lifting by the frame allows air springs to be in their extended position, where the rub-ber bladder (Figure 64.42) will not be damaged. With the suspension hanging free, height sensors lengthen to their maximum position. If the system is on, the computer sees this as a “high car” condition and responds by bleeding pressure from the air springs. If the vehicle is lowered to the ground while the springs are in this position, the rubber could be damaged if the air spring bags happen to fold inward.

When using a hydraulic jack to lift a vehicle, lift by the front crossmember and manufacturer’s specifi ed rear lift points in front of the rear tires. Before towing a vehicle with an automatic leveling system, be sure to check the service information for precautions.

Prior to doing a wheel alignment, the vehicle must be set at regular curb height. Failing to do this will result in a faulty wheel alignment.

ELECTRONICALLY CONTROLLED SHOCK ABSORBERS

Some shock absorbers are electronically controlled to provide a ride that is more fi rm or more soft than nor-mal. When a fi rm ride is selected, an actuator motor rotates in response to an electronic signal to reposi-tion a valve in the shock, restricting oil movement and causing a rougher ride.

Rubberbladder

Figure 64.42 An air spring strut assembly from an elec-tronic suspension system.

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PRC Diagnostic Trouble Codes (DTCs)

Code Defect

6

123457

1314

No system problem

Left rear actuator circuitRight rear actuator circuitRight front actuator circuitLeft front actuator circuitSoft relay control circuit shortedPRC control moduleFirm relay control circuit shortedRelay control circuit

Figure 64.41 PRC system diagnostic trouble codes (DTCs).

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Plastic locatorretainer tabs

Figure 64.43 Squeeze the plastic retainers and lift the motor from the top of the strut.

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1214 CHAPTER 64

and the control tube. With the electrical wiring discon-nected, the actuator control tube can be turned with a small screwdriver to put it into the desired position. In different positions, electrical resistance is tested using an ohmmeter and the results are compared to specifi cations.

To diagnose the actuator system, you will need wiring color codes and specifi c instructions. A typical diagnosis procedure will have you rotate the actuator motor to where it is normally positioned under different commands and make identifying marks on the actuator

REVIEW QUESTIONS

ASE-STYLE REVIEW QUESTIONS

1. A _______ shock absorber expands to its full travel when not installed.

2. What is added when installing a Macpherson strut cartridge to help it conduct heat to the outside of the strut?

3. If a wheel bearing burns and damages the spindle, what part should be replaced?

4. Are there any holes in a good ball joint boot?

5. What are two directions ball joints are checked for wear?

6. Which kind of ball joint is more common, tension or compression?

7. When a wear indicator ball joint wears, does the shoulder move into or out of the ball joint?

8. When a replacement ball joint is held in place with nuts and bolts, what held the previous ball joint in position?

9. What is used with a spring compressor to aid in the removal and replacement of coil springs?

10. What is the name of the end of a coil spring that aligns in the coil spring seat in the frame or lower control arm?

1. Technician A says that it is normal for a small amount of moisture to be on the outside of a shock absorber. Technician B says that if the outside of the shock absorber body has been damaged, replace it along with the one on the other side of the car. Who is right?

a. Technician A c. Both A and B

b. Technician B d. Neither A nor B

2. Which of the following is/are true about shock absorber rubber mounts?

a. A shock mount should be tightened until the rubber bumper is totally compressed.

b. Shock absorber bushings should be lubricated with light oil.

c. When tightening a nut on the top of a shock rod, the rod must be held from turning.

d. None of the above

3. When replacing stabilizer link bushings, which of the following statements is/are true?

a. Both front wheels can be on the ground.

b. Both front wheels can be off the ground.

c. Both A and B

d. Neither A nor B

4. Technician A says that a load-carrying ball joint must be unloaded to test it. Technician B says that a load-carrying ball joint must be replaced

if there is any perceptible movement. Who is right?



5. Which of the following is/are true statements?

a. When checking ball joints for wear, applying the brakes will temporarily eliminate wheel bearing clearance.

b. Spring sag can result in abnormal tire wear.

c. Both A and B

d. Neither A nor B

6. When jacking against a control arm to compress a coil spring, the jack should be positioned:

a. Perpendicular (90 degrees) to the tires

b. Parallel to the tire tread, in line with the vehicle

c. Both A and B

d. Neither A nor B

7. Technician A says to align the cotter pin hole in a ball joint so it is parallel to the brake backing plate. Technician B says that after tightening to the correct torque specification, loosen the ball joint locknut to align the cotter pin hole. Who is right?





a cartridge installed into the original strut housing. Who is right?



10. Which of the following is/are true about worn suspension bushings?

a. Worn bushings can change wheel alignment settings.

b. The car can pull to one side when braking.

c. The car can pull to one side all of the time.

d. All of the above

8. Which of the following is/are true about shock absorbers?

a. Cupped tire wear could be the result of a bad shock absorber.

b. The sound of the fl uid being forced through the valves in the shock is normal.

c. Air shocks are designed to raise a vehicle’s height.

d. All of the above

9. A Macpherson strut shock absorber is leaking badly. Technician A says that sometimes an entire strut assembly must be replaced. Technician B says that some vehicles use


chapter 64 suspension system service · the entire strut assembly. occasionally a strut cartridge...

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