Wheel Alignment Specifications & Adjustment Procedures: Adjustments Pontiac Sunfire I

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 WHEEL MOUNTING SURFACE CHECK 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 and TIRE DIAGNOSIS - IRREGULAR OR PREMATURE WEAR in Tires and Wheels.
2. Inspect the runout of the wheels and the tires. Refer to «TIRE AND WHEEL RUNOUT SPECIFICATIONS»(ref-189096-S03881307232005090600000) in Vibration Diagnosis and Correction.
3. Inspect the wheel bearings for backlash and excessive play. Refer to «WHEEL BEARINGS DIAGNOSIS»(ref-169054-S34044480832004112900000) 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 «SPECIFICATIONS»(ref-175143-S37534738982005041500000) 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»(ref-169054-S32467728352004112900000) in Suspension General Diagnosis.
8. Inspect the vehicle trim height. Refer to «TRIM HEIGHT INSPECTION PROCEDURE»(ref-169054-S40974977762004112900000) in Suspension General Diagnosis.
9. Inspect the steering wheel for excessive drag or 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, sample cases, etc. If normally carried in the vehicle, these items should remain in the vehicle during alignment adjustments. Give consideration also 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. IMPORTANT: 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»(ref-189098-S29719071012005092200000) .

Front Caster Adjustment

The front caster is not adjustable. If the front caster angle is not within specifications, inspect for suspension support misalignment or front suspension damage. Refer to Replace any damaged suspension components as necessary.

Scheme 4

Scheme 5

1. Loosen both strut to knuckle nuts just enough to allow for movement.
2. If the strut has not been modified previously, perform the following steps before continuing with the wheel alignment: 2.1. Disconnect the strut from the knuckle. Refer to «STRUT ASSEMBLY REPLACEMENT»(ref-174832-S41886601992005041100000) in Front Suspension. 2.2. File the lower hole until the outer flange slot matches the inner flange slot. 2.3. Connect the strut to the knuckle. Refer to «STRUT ASSEMBLY REPLACEMENT»(ref-174832-S41886601992005041100000) in Front Suspension.
3. Adjust the camber to specification by moving the top of the wheel in or out. Refer to «Wheel Alignment Specifications»(ref-189098-S29719071012005092200000) . NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
4. Tighten the strut to knuckle nuts to 180N.m (133 lb ft).

Scheme 6

1. Ensure that the steering wheel is set in a straight ahead position.
2. Loosen the tie rod jam nut (5).
3. Adjust the toe to specification by turning the adjuster (6). Refer to «Wheel Alignment Specifications»(ref-189098-S29719071012005092200000) . NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
4. Install the tie rod jam nut (5). Tighten Tighten the tie rod jam nut (5) to 68 N.m (50 lb ft).

Scheme 7

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 return ability 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.

Scheme 8

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.

Scheme 9

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.

Scheme 10

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.