Suspension and Steering
Scope
The G1 tests inspection and replacement of worn parts plus a working understanding of alignment angles. Know struts and shocks, coil and leaf springs, control arms and bushings, ball joints, tie rods, sway bar links, steering racks, electric power steering, and hub bearings.
Concepts you must own
- Camber: the inward or outward tilt of the wheel viewed from the front. Too much negative camber wears the inner edge of the tire.
- Caster: the forward or rearward tilt of the steering axis. More positive caster improves high-speed stability and returnability.
- Toe: wheels pointing in or out relative to each other. Incorrect toe produces rapid, feathered edge wear.
- Play checks: a ball joint shows vertical play with the wheel grabbed at 12 and 6 o'clock; a tie rod end shows side play at 3 and 9.
- Hub bearings: a bad bearing often changes tone when the vehicle is loaded in a turn.
- Power steering: hydraulic systems need the specified fluid; electric systems have no fluid and may need a steering angle sensor reset after alignment.
Traps
Pulling is not automatically an alignment problem. Swap the front tires side to side first to rule out a radial tire pull. A vehicle that pulls only while braking is a brake fault, not alignment. Conical or feathered wear patterns each point at different angles. Do not condemn a strut for a noise that comes from a sway bar link.
Worked example
A vehicle leads to the right and the right front tire shows inner edge wear. Camber is likely too negative on that side or caster is unequal. Measure and adjust to specification, then verify with a road test on a level crown-free road.
Rule of thumb
Pull usually follows the side with less positive caster or more positive camber; tire swap comes first.