The following procedures require the use of alignment equipment. The Do-it-Yourself mechanic should not attempt to perform any wheel alignment procedures. Expensive alignment tools are needed and would not be cost efficient to purchase these tools. The wheel alignment should be performed by a certified alignment technician using the proper alignment tools.
Front end alignment refers to the angular relationship between the front wheels, the front suspension attaching parts and the ground. The angle of the knuckle away from the vertical, the pointing in or "toe-in" of the front wheels, the tilt of the front wheels from vertical (when viewed from the front of the vehicle) and the tilt of the suspension members from vertical (when viewed from the side of the vehicle), all these are involved in front alignment.
The Pontiac Fiero is designed with independent front and rear suspension that is service adjustable, making four wheel alignment possible.
The Camber angle is the tilting of the wheels from the vertical when viewed from the rear of the car. When the wheels tilt outward at the top, the camber is said to be positive (+). When the wheels tilt inward at the top, the camber is said to be negative (-). Negative camber is the most common because as the springs sag down, the camber becomes negative which will wear the inside of the tires. The amount of tilt is measured in degrees from the vertical and the measurement is called camber angle.
Camber angle can be increased approximately 1° by removing the upper ball joint, rotating it one-half turn, and installing it with the flat of the upper flange on the inboard side of the control arm. For assistance, refer to the "Upper Ball Joint" procedures in this section.
Caster angle can be changed by 1° by changing the position of the washers located between the legs of the upper control arm. Placing the thinner washer in front will increase caster, while placing it at the back will reduce caster.
A kit is available containing two washers, one of 3mm thickness and one of 9mm thickness. Whenever adjusting caster, it is important to always use two washers totaling 12mm thickness, with one washer at each end of locating tube.
CAMBER AND CASTER
The caster angle is the forward or rearward tilting of the wheel axis (at the top) from the vertical. A rearward tilt is a positive (+) angle, and a forward tilt is a negative (-) angle. Caster influences directional stability and steering effort, but does not affect tire wear. Weak springs or overloading the vehicle will affect the caster angle.
- Before adjusting the camber and caster angles, bounce (jounce) the front and rear bumpers three times each.
- Loosen the upper control arm shaft bolts to tilt the wheel from the vertical to change the Camber angle. Tilt the wheel forward and rearward to change the Caster angle.
If the upper control arms are removed for any reason, the paddle nut assemblies must be replaced as outlined in the Upper Control Arm Procedure in this section.
- Torque the upper control shaft bolts to 52 ft. lbs. (70 Nm) + 1 / 4 turn (90°).
- The Toe angle must be adjusted after camber/caster have been adjusted.
The Toe is the dimension which allows the parallel rolling of all four wheels. As the vehicle is directed down the highway, the components which make up the steering and suspension are subjected to dynamic forces. The toe angle is when you are looking down on the front suspension from above. When the front of the tires are towards each other, the toe is in (toe-in). When the rear of the tires are towards each other, the toe is out (toe-out). Most vehicles are set with the toe-in.
- Position the vehicle on the alignment equipment and obtain the toe-in reading.
- Loosen the jam nut on the tie rods.
- Rotate the tie rod to adjust the toe to specification in the chart in this section.
- Torque the jam nuts to 47 ft. lbs. (64 Nm).