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 a 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 can only be performed at a properly equipped shop.
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.
If the caster still cannot be adjusted within the limits, inspect or replace any damaged or worn suspension parts.
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 negative camber. In 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.
Toe is the amount measured in a fraction of an inch, that the front wheels are closer together at one end than the other. Toe-in means that the front wheels are closer together at the front of the tire than at the rear; toe-out means that the rear of the tires are closer together than the front.
Although it is recommended that this adjustment be made by your dealer or a qualified shop, you can make it yourself if you make very careful measurement. The wheels must be dead straight ahead. The car must have a full tank of gas, all fluids must be at their proper levels, all other Suspension and Steering adjustments must be correct and the tires must be properly inflated to their cold specification.
- Toe can be determined by measuring the distance between the centers of the tire treads, at the front of the tire and the rear. If the tread pattern of your car's tires makes this impossible, you can measure between the edges of the wheel rims, but be sure to move the car and measure in a few places to avoid errors caused by bent rims or wheel run-out.
- If the measurement is not within specifications, loosen the four retaining clamp lock nuts on the adjustable tie rods.
- Turn the left and right tie rods EQUAL amounts until the measurements are within specifications.
- Tighten the lockbolts and then recheck the measurements. Check to see that the steering wheel is still in the proper position. If not, remove it and reposition it as detailed later in this section.