Wheel Alignment Measurement
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/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 and adjustments in order to ensure correct alignment readings:
^ Inspect the tires for the proper inflation and irregular tire wear. Refer to Tire Inflation Pressure Specifications and Tire Diagnosis - Irregular or Premature Wear.
^ Inspect the runout of the wheels and the tires. Refer to Tire and Wheel Runout Specifications in Vibration Diagnosis and Correction under Steering and Suspension Testing and Inspection.
^ Inspect the wheel bearings for backlash and excessive play. Refer to Wheel Bearings Diagnosis in Suspension General Diagnosis.
^ Inspect the ball joints and tie rod ends for looseness or wear.
^ Inspect the control arms and stabilizer shaft for looseness or wear.
^ Inspect the steering gear for looseness at the frame. Refer to Fastener Tightening Specifications in Power Steering System.
^ Inspect the shock absorbers for wear, leaks, and any noticeable noises. Refer to Struts or Shock Absorbers On-Vehicle Testing in Suspension General Diagnosis.
^ Inspect the vehicle trim height. Refer to Trim Height Specifications.
^ Inspect the steering wheel for excessive drag or poor return due to stiff or rusted linkage or suspension components.
^ 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.
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.
Front Caster and Camber Adjustment
^ Tools Required
- J 45845 Caster and Camber Adjusting Tool
The caster and camber adjustments are made by loosening the lower control arm adjustment bolts and repositioning the lower control arm.
Important: Before adjusting the caster and camber angles, jounce the front bumper 3 times to allow the vehicle to return to normal height.
Measure and adjust the caster and the camber with the vehicle at curb height. The front suspension Z dimension and the rear suspension D dimension are indicated in Trim Heights. Refer to Trim Height Specifications.
1. For an accurate reading, do not push or pull on the tires during the alignment process.
2. Determine the caster angle (2, 3).
3. Determine the camber angle (2, 3).
4. Install the J 45845 to the lower control arm and the frame.
5. Loosen the lower control arm adjustment nuts.
Notice: Refer to Fastener Notice in Service Precautions.
6. Adjust the caster and the camber angle by repositioning the lower control arm until the specifications have been met. When the adjustments are complete, hold the lower control arm in position so that the specifications do not change while tightening the lower control arm adjustment bolts.
^ Tighten the lower control arm adjustment bolts to 135 Nm (100 ft. lbs.).
7. Verify that the caster and the camber are still within specifications. Refer to Wheel Alignment Specifications. When the caster and camber are within specifications, adjust the toe. Refer to Front Toe Adjustment.
Front Toe Adjustment
1. Loosen the jam nut on the outer tie rod.
2. Rotate the inner tie rod to the required toe specification setting. Refer to Wheel Alignment Specifications.
Notice: Care must be taken that the boots are not twisted when rotating the inner tie rods, or damage to the boots may result.
3. Tighten the jam nut to the outer tie rod.
^ Tighten the nut to 75 Nm (55 ft. lbs.).
Notice: Refer to Fastener Notice in Service Precautions.
4. Check the toe setting after tightening. Refer to Wheel Alignment Specifications.
5. Re-adjust the toe setting if necessary.
Rear Camber Adjustment
^ Tools Required
- J 45845 Caster and Camber Adjusting Tool
1. Install J 45845 to the lower control arm and the frame.
2. Loosen the lower control arm to frame bolt.
3. Adjust the camber angle by turning the turnbuckle on J 45845 until the specifications have been met.
^ Tighten the bolt to 150 Nm (111 ft. lbs.).
Notice: Refer to Fastener Notice in Service Precautions.
4. Verify that the camber is still with specifications. Refer to Wheel Alignment Specifications.
5. Adjust the rear toe. Refer to Rear Toe Adjustment.
Rear Toe Adjustment
1. Loosen the adjustment link jam nuts (1).
Important: Complete the left and right rear toe adjustments separately, per wheel. Using the following procedure.
2. In order to adjust the toe, rotate the turnbuckle (2).
^ Tighten the jam nuts to 75 Nm (55 ft. lbs.).
Notice: Refer to Fastener Notice in Service Precautions.
3. Recheck the toe setting after tightening.
4. Readjust the toe setting if necessary. Refer to Wheel Alignment Specifications.