Wheel Alignment Specifications & Adjustment Procedures Buick LeSabre VIII

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FASTENER TIGHTENING SPECIFICATIONS

Fastener Tightening Specifications

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MEASURING WHEEL ALIGNMENT

Steering and vibration complaints are not always the result of improper alignment. One possible cause is wheel and tire imbalance. Another possibility is tire lead due to worn or improperly manufactured tires. Lead is the vehicle deviation from a straight path on a level road without pressure on the steering wheel. Refer to RADIAL TIRE LEAD/PULL CORRECTION in Tires and Wheels in order to determine if the vehicle has a tire lead problem.

Before performing any adjustment affecting wheel alignment, perform the following inspections and adjustments in order to ensure correct alignment readings

1. Inspect the tires for the proper inflation and irregular tire wear. Refer to «TIRE INFLATION PRESSURE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) and «TIRE DIAGNOSIS - IRREGULAR OR PREMATURE WEAR»(/buick/lesabre/viii-2000-2005/remont/wheel-tire-system/#tires-wheels) in Tires and Wheels.
2. Inspect the runout of the wheels and the tires. Refer to «TIRE & WHEEL RUNOUT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) .
3. Inspect the wheel bearings for backlash and excessive play. Refer to «WHEEL BEARINGS DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/suspension-front/#suspension-general-diagnosis__wheel-bearings-diagnosis) in Suspension General Diagnosis.
4. Inspect the ball joints and tie rod ends for looseness or wear.
5. Inspect the control arms and stabilizer shaft for looseness or wear.
6. Inspect the steering gear for looseness at the frame. Refer to «FASTENER TIGHTENING SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-power-steering/#power-steering-system__fastener-tightening-specifications) in Power Steering System.
7. Inspect the struts/shock absorbers for wear, leaks, and any noticeable noises. Refer to «STRUTS OR SHOCK ABSORBERS ON-VEHICLE TESTING»(/buick/lesabre/viii-2000-2005/remont/suspension-front/#suspension-general-diagnosis__struts-or-shock-absorbers-on-vehicle-testing) in Suspension General Diagnosis.
8. Inspect the vehicle trim height. Refer to «TRIM HEIGHT INSPECTION PROCEDURE»(/buick/lesabre/viii-2000-2005/remont/suspension-front/#suspension-general-diagnosis) in Suspension General Diagnosis.
9. Inspect the steering wheel for excessive drag or poor return due to stiff or rusted linkage or suspension components.
10. Inspect the fuel level. The fuel tank should be full or the vehicle should have a compensating load added.

Give consideration to excess loads, such as tool boxes, samples cases, etc. If normally carried in the vehicle, these items should remain in the vehicle to the condition of the equipment being used for the alignment. Follow the equipment manufacturer's instructions.

Satisfactory vehicle operation may occur over a wide range of alignment settings. However, if the setting exceeds the service allowable specifications, correct the alignment to the service preferred specifications. Refer to WHEEL ALIGNMENT SPECIFICATIONS .

Perform the following steps in order to measure the front and rear alignment angles

1. Install the alignment equipment according to the manufacturer's instructions.
2. Jounce the front and the rear bumpers 3 times prior to checking the wheel alignment.
3. Measure the alignment angles and record the readings. NOTE: When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear wheel alignment angles first in order to obtain proper front alignment angles.
4. Adjust alignment angles to vehicle specification, if necessary. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) .

FRONT CASTER ADJUSTMENT

Use the following procedure in order to prepare the top strut mounting holes

1. Remove the top 3 fasteners from the strut tower.
2. Lift the front of the vehicle by the body in order to separate the strut from the inner wheelhouse.
3. Pop out the 2 guide pins.
4. Hand file the excess metal in order to make slotted holes.
5. Paint the exposed metal using rust preventative paint or primer.
6. Lower the front of the vehicle.
7. Install the strut attaching fasteners. Do not tighten the fasteners at this time. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
8. Move the top of the strut forward or rearward in order to adjust the caster. A 1 mm (0.040 in) position change at the tower is about equal to a 0.1 degree change in the caster. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) . Tighten the strut fasteners to 47 N.m (35 ft lbs).
9. Perform a complete wheel alignment.

FRONT CAMBER ADJUSTMENT

Note. Tools Required: Camber Adjustment Tool (J 39601).

1. Raise and support the vehicle.
2. Remove the tire and wheel. Refer to «TIRE & WHEEL REMOVAL & INSTALLATION»(/buick/lesabre/viii-2000-2005/remont/wheel-tire-system/#tires-wheels__tire-wheel-removal-installation) in Tires and Wheels. NOTE: Do not allow the bolts to turn. This will ruin the serrated shoulder.
3. Remove the nut and tap the upper and lower bolt from the strut and knuckle.
4. Separate the strut from the knuckle. NOTE: It is necessary to grind the lower bolt hole on the strut to achieve proper camber setting. If camber specification is not achieved by this procedure check for bent or worn parts.
5. Using a round file or a die grinder file the inner metal plate to the outside plates diameter.
6. File excess metal to make the slotted holes.
7. Paint the exposed metal with rust preventive paint or primer.
8. Replace the strut to the knuckle.
9. Install both the upper and lower bolts.
10. Do not tighten at this time (leave loose).
11. Install the J 39601 to the bottom strut bolt. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
12. Using the J 39601, set the camber. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) . Tighten the upper strut to knuckle nut to 225 N.m (166 ft lbs).
13. Remove the J 39601. Tighten the lower strut to knuckle nut to 225 N.m (166 ft lbs).
14. Replace the tire and wheel. Refer to «TIRE & WHEEL REMOVAL & INSTALLATION»(/buick/lesabre/viii-2000-2005/remont/wheel-tire-system/#tires-wheels__tire-wheel-removal-installation) in Tires and Wheels.
15. Lower the vehicle.
16. Perform a wheel alignment. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) .

FRONT TOE ADJUSTMENT

1. Loosen the lock nuts on the tie rod. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. CAUTION: Care must be taken that the boots are not twisted when rotating the inner tie rods, or damage to the boots may result.
2. Rotate the inner tie rod to adjust the toe. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) . Tighten the lock nuts to 64 N.m (47 ft lbs).
3. Adjust the boots as needed in order to prevent damage.

REAR TOE ADJUSTMENT

Note. Complete the left and right rear toe adjustments separately, per wheel. Use the following procedure.

1. Loosen the inner adjustment link cam nut. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
2. In order to adjust the toe, rotate the cam bolt. Refer to «FASTENER TIGHTENING SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures__fastener-tightening-specifications) . Tighten the cam nut (2) to 91 N.m (67 ft lbs).
3. Recheck the toe setting after tightening.
4. Readjust the toe setting if necessary. Refer to «WHEEL ALIGNMENT SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/wheel-alignment/#wheel-alignment-specifications-adjustment-procedures) .

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Caster is the tilting of the uppermost point of the steering axis either forward or backward, when viewed from the side of the vehicle. A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect the tire wear and is not adjustable on this vehicle. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster.

With too little positive caster, steering may be touchy at high speed and wheel returnability may be diminished when coming out of a turn. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.

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Camber is the tilting of the wheels from the vertical when viewed from the front of the vehicle. When the wheels tilt outward at the top, the camber is positive (+). When the wheel tilts inward at the top, the camber is negative (-). The amount of tilt is measured in degrees from the vertical. Camber settings influence the directional control and the tire wear.

Too much positive camber will result in premature wear on the outside of the tire and cause excessive wear on the suspension parts.

Too much negative camber will result in premature wear on the inside of the tire and cause excessive wear on the suspension parts.

Unequal side-to-side camber of 1 degree or more will cause the vehicle to pull or lead to the side with the most positive camber.

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Toe is a measurement of how much the front and/or rear wheels are turned in or out from a straight-ahead position. When the wheels are turned in, toe is positive (+). When the wheels are turned out, toe is negative (-). The actual amount of toe is normally only a fraction of a degree. The purpose of toe is to ensure that the wheels roll parallel.

Toe also offsets the small deflections of the wheel support system that occur when the vehicle is rolling forward. In other words, with the vehicle standing still and the wheels set with toe-in, the wheels tend to roll parallel on the road when the vehicle is moving.

Improper toe adjustment will cause premature tire wear and cause steering instability.

SETBACK DESCRIPTION

Setback applies to both the front and the rear wheels. Setback is the amount that one wheel may be aligned behind the other wheel. Setback may be the result of a road hazard or a collision. The first clue is a caster difference from side-to-side of more than 1 degree.

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The front wheels aim or steer the vehicle. The rear wheels control tracking. This tracking action relates to the thrust angle (3). The thrust angle is the path that the rear wheels take. Ideally, the thrust angle is geometrically aligned with the body centerline (2).

In the illustration, toe-in is shown on the left rear wheel, moving the thrust line (1) off center. The resulting deviation from the centerline is the thrust angle.

LEAD/PULL DESCRIPTION

Lead/pull is the deviation of the vehicle from a straight path, on a level road, without hand pressure on the steering wheel.

Lead/pull is usually caused by the following factors

1. Tire construction.
2. Uneven brake adjustment.
3. Wheel alignment.

The way in which a tire is built may produce lead/pull. The rear tires will not cause lead.

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A vehicle pulls or leads in one direction during hard acceleration. A vehicle pulls or leads in the other direction during deceleration.

The following factors may cause torque steer to be more apparent on a particular vehicle

1. A slightly smaller diameter tire on the right front increases a right torque lead. Inspect the front tires for differences in the brand, the construction, or the size. If the tires appear to be similar, change the front tires from side-to-side and retest the vehicle. Tire and wheel assemblies have the most significant effect on torque steer correction.
2. A large difference in the right and left front tire pressure.
3. Left-to-right differences in the front view axle angle may cause significant steering pull in a vehicle. The pull will be to the side with the most downward sloping axle from the differential to the wheels. Axles typically slope downward from the differential. The slope of the transaxle pan to level ground may be used as an indication of bias axle angles. The side with the higher transaxle pan, shown on the left side of the illustration, has the most downward sloping axle angle.

MEMORY STEER DESCRIPTION

Memory steer is when the vehicle wants to lead or pull in the direction the driver previously turned the vehicle. Additionally, after turning in the opposite direction, the vehicle will want to lead or pull in that direction.

WANDER DESCRIPTION

Wander is the undesired drifting or deviation of a vehicle to either side from a straight path with hand pressure on the steering wheel. Wander is a symptom of the vehicle's sensitivity to external disturbances, such as road crown and crosswind, and accentuated by poor on-center steering feel.

SCRUB RADIUS DESCRIPTION

Ideally, the scrub radius is as small as possible. Normally, the SAI angle and the centerline of the tire and the wheel intersect below the road surface, causing a positive scrub radius. With struts, the SAI angle is much larger than the long arm/short arm type of suspension. This allows the SAI angle to intersect the camber angle above the road surface, forming a negative scrub radius. The smaller the scrub radius, the better the directional stability. Installing aftermarket wheels that have additional offset will dramatically increase the scrub radius. The newly installed wheels may cause the centerline of the tires to move further away from the spindle. This will increase the scrub radius.

A large amount of scrub radius can cause severe shimmy after hitting a bump. Four-wheel drive vehicles with large tires use a steering damper to compensate for an increased scrub radius. Scrub radius is not directly measurable by the conventional methods. Scrub radius is projected geometrically by engineers during the design phase of the suspension.

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See also:
• RADIAL TIRE LEAD/PULL CORRECTION
• WHEEL BEARINGS DIAGNOSIS
• FASTENER TIGHTENING SPECIFICATIONS
• STRUTS OR SHOCK ABSORBERS ON-VEHICLE TESTING
• TRIM HEIGHT INSPECTION PROCEDURE
• TIRE & WHEEL REMOVAL & INSTALLATION
• TIRE INFLATION PRESSURE SPECIFICATIONS
• FASTENER TIGHTENING SPECIFICATIONS