Chassis, Steering, Suspension, and Brake Systems Servicing
This domain tests alignment angles, steering and suspension play, brake inspection, hydraulic bleeding, and ABS basics.
Core rules
- Alignment: camber is vertical tilt, caster is steering-axis tilt, toe is the front-to-rear difference across the tires. Set toe last, with the steering centered and the vehicle at curb weight.
- Check play before alignment: ball joints, tie-rod ends, wheel bearings, idler arm.
- Tire wear tells the story: shoulder wear suggests camber or toe; cupping suggests worn shocks or imbalance.
- Brake pads: replace at the manufacturer's minimum, often around 2 mm; measure rotor thickness and runout.
- Bleed from farthest wheel to nearest - typically RR, LR, RF, LF - keeping the reservoir full.
- Use the specified DOT fluid; DOT 5 silicone is not interchangeable with DOT 3 or 4.
Worked example
A car pulls right and the right front tire shows inner-edge wear. Reasoning: a pull can come from brake drag, tire pressure difference, or alignment. Check pressures and brake temperatures first; if equal, measure camber and caster. Excessive negative camber on the right front explains both the pull and the inner wear. Correct the alignment to specification, set toe last, and recheck the steering wheel angle.
Traps
Bleeding in the wrong order; pressing the brake pedal with a caliper removed; letting the reservoir run dry; mixing DOT fluids; aligning with worn tie rods; supporting the vehicle on the jack only.