Wheel Alignment System: Adjustments Chevrolet Tahoe III

Wheel Alignment Measurement

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/pull is defined as follows: At a constant highway speed on a typical straight road, lead/pull is the amount of effort required at the steering wheel to maintain the vehicle's straight path. 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 order to determine if the vehicle has a tire lead problem.

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

1. Inspect for visible damage to the suspension components and replace as necessary.
2. Inspect the tires for the proper inflation and irregular tire wear. Refer to «Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label»(ref-364496-S41708322732010063000000) and «Tire Diagnosis - Irregular or Premature Wear»(ref-364499-S22968146512010063000000) .
3. Inspect the runout of the wheels and the tires. Refer to «Tire and Wheel Runout Specifications»(ref-364570-S04900022482010063000000) .
4. Inspect the wheel bearings for backlash and excessive play. Refer to «Wheel Bearings Diagnosis»(ref-364520-S32042260652010063000000) .
5. Inspect the ball joints for looseness or wear.
6. Inspect the tie rod ends for looseness or wear.
7. Inspect the control arms and stabilizer shaft for looseness or wear.
8. Inspect the steering gear for looseness at the frame. Refer to «Fastener Tightening Specifications»(ref-364521-S17319476652010063000000) .
9. Inspect the struts/shock absorbers for wear, leaks, and any noticeable noises. Refer to «Suspension Strut and Shock Absorber Testing - On Vehicle»(ref-364520-S29906515152010063000000) .
10. Inspect the vehicle trim height. Refer to «Trim Height Inspection»(ref-364520-S00472386902010063000000) .
11. Inspect the steering wheel for excessive drag or poor return due to stiff or rusted linkage or suspension components.
12. 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.
4. Adjust alignment angles to vehicle specification, if necessary. Refer to «Wheel Alignment Specifications»(ref-364634-S35268141302010063000000) .

Front Caster and Camber Adjustment

1. The caster and camber adjustments are made by rotating the offset cam bolt and the cam in the slotted frame bracket in order to reposition the control arm.
2. For an accurate reading, do not push or pull on the tires during the alignment process.
3. Determine the caster angle (2).
4. Determine the positive camber (2) or negative camber (3) angle.
5. Remove the pinned adjusting cam insert. Do not reinstall the cam insert.
6. Loosen the upper control arm cam adjustment bolts.
7. Adjust the caster and the camber angle by turning the cam bolts until the specifications have been met. When the adjustments are complete, hold the cam bolt head in order to ensure the cam bolt position does not change while tightening the nut. Tighten: Tighten the cam nuts to 190 N.m (140 lb ft).
8. Verify that the caster and the camber are still within specifications. Refer to «Wheel Alignment Specifications»(ref-364634-S35268141302010063000000) . When the caster and camber are within specifications, adjust the toe. Refer to «Wheel Alignment - Steering Wheel Angle and/or Front Toe Adjustment»(ref-364634-S00768259652010063000000) .

Wheel Alignment - Steering Wheel Angle and/or Front Toe Adjustment

1. Loosen the jam nut on the inner tie rod (1).
2. Rotate the inner tie rod (2) to the required toe specification setting. Refer to «Wheel Alignment Specifications»(ref-364634-S35268141302010063000000) .
3. Install the jam nut (1) on the tie rod and tighten to 75 N.m (55 lb ft).
4. Check the toe setting after tightening.
5. Re-adjust the toe setting if necessary.

Scheme 3

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 4

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. 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.