If the tires are worn unevenly, if the vehicle is not stable on the highway or if the handling seems uneven in spirited driving, wheel alignment should be checked. If an alignment problem is suspected, first check tire inflation and look for other possible causes such as worn suspension and steering components, accident damage or unmatched tires. Repairs may be necessary before the wheels can be properly aligned. Wheel alignment requires sophisticated equipment and should only be performed at a properly equipped shop.
The following conditions should be met before checking the wheel alignment:
See Figure 1
Looking at the wheels from the front of the vehicle, camber adjustment is the tilt of the wheel. When the wheel is tilted in at the top, this is called negative camber. When you are driving the vehicle through a turn, a slight amount of negative camber helps maximize contact of the outside tire with the road. Too much negative camber makes the vehicle unstable in a straight line.
On Ford Mustangs, the camber is adjusted by removing the pop-rivet in the camber plate. Loosen the 3 nuts which hold the strut mount to the body apron, then move the top of the strut to the desired position. Once the strut is in position, the top nuts should be tightened to 40-55 ft. lbs. (54-75 Nm) and a new pop-rivet should be installed.
See Figure 2
Wheel alignment is defined by three different adjustments in three planes. Looking at the vehicle from the side, caster angle describes the steering axis rather than a wheel angle. The steering knuckle is attached to the strut at the top and the control arm at the bottom. The wheel pivots around the line between these points to steer the vehicle. When the upper point is tilted back, this is described as positive caster. Having a positive caster tends to make the wheels self-centering, increasing directional stability. Excessive positive caster makes the wheels hard to steer, while an uneven caster will cause a pull to one side. Caster is usually determined by the suspension components (in a fixed position by body geometry) and is usually not adjustable.
See Figures 3 and 4
Looking down at the wheels from above the vehicle, toe alignment is the distance between the front of the wheels relative to the distance between the back of the same wheels. If the wheels are closer at the front, they are said to be toed-in or to have a negative toe. A small amount of negative toe enhances directional stability and provides a smoother ride on the highway.Toe-In Adjustment
See Figures 3 and 4
- Turn the steering wheel, from left to right, several times and center.
If car has power steering, start the engine before centering the steering wheel.
- Secure the centered steering wheel with a steering wheel holder, or any device that will keep it centered.
- Release the tie rod end bellows clamps so the bellows will not twist while an adjustment is made. Loosen the jam nuts on the tie rod ends. Adjust the left and right connector sleeves until each wheel has one-half of the desired toe setting.
- After the adjustment has been made, tighten the jam nuts and secure the bellows clamps.
- Release the steering wheel lock and check for steering wheel center. Readjust, if necessary until the steering wheel is centered, and the toe is within specs.