Suspension, Steering, and Alignment
Core concepts
Know suspension types (MacPherson strut, double wishbone, solid axle), spring rates, shock absorber function, and the purpose of sway bars. Understand steering geometry: camber, caster, toe, steering axis inclination (SAI), and included angle. Be able to explain thrust angle and how it relates to rear axle alignment. Know the difference between static and dynamic balance and how tire wear patterns reveal alignment faults.
Traps to expect
Questions often confuse camber and caster: camber is the inward or outward tilt of the wheel viewed from the front, while caster is the forward or rearward tilt of the steering axis viewed from the side. Caster affects straight-line stability and steering return; camber affects tire wear and cornering grip. Another trap is toe: excessive toe-in or toe-out causes feathered tread wear. Also remember that a bent strut can change camber and SAI together, and that thrust angle is not the same as toe.
Worked example
A tire shows feathered edges across the tread. Rule of thumb: feathered wear indicates incorrect toe, while one-sided wear indicates camber. Check and adjust toe after verifying ride height and tire pressure, since both affect readings.
Study strategy
Practice reading an alignment printout, matching wear patterns to angles, and explaining how worn bushings or bent components change geometry.