Chassis, Steering, Suspension and Brake Systems Diagnosis
Tyres and geometry
Chassis diagnosis starts at the tyres: pressure, wear patterns, balancing and runout. Uneven wear indicates alignment, inflation or suspension faults. Understand camber, caster, toe and thrust angle, and how each affects wear and handling. Toe wear shows as feathered edges, camber wear as one-sided shoulder wear, and incorrect caster affects steering return and stability rather than wear.
Suspension and steering
Inspect springs, dampers, bushes, ball joints, tie rod ends and wheel bearings. A worn damper causes bounce, cupping tyre wear and poor braking stability. Steering play can come from the rack, column, tie rods or wheel bearings; isolate by observing each joint while an assistant rocks the wheel. Power steering faults may be hydraulic (pump, fluid, leaks) or electric (motor, sensor, module).
Brake diagnosis
Brakes convert hydraulic pressure into friction. Diagnosis covers pedal feel (spongy means air in hydraulic system, long pedal means rear brake adjustment or master cylinder fault), pull under braking (seized caliper, collapsed hose, uneven friction), noise and vibration (warped discs, pad wear indicators, runout). ABS faults require checking wheel speed sensors, reluctor rings and wiring before condemning the hydraulic unit. Brake fluid absorbs moisture and must be tested and replaced per schedule.
Traps
Questions often confuse a seized caliper with a collapsed flexible hose; both cause drag, but the hose can act as a one-way valve. Another trap is diagnosing a wheel bearing as a tyre or CV noise; bearing noise changes with cornering load. Candidates also forget that ABS warning lamps can be triggered by low fluid or voltage.
Rule of thumb
If a wheel is hot after a short drive and the vehicle pulls that way, suspect a dragging brake. Crack the bleeder; if pressure releases and drag stops, the hose is collapsed.
Worked example
A vehicle pulls right under braking and the right front wheel runs hot. Jack the corner, the wheel is hard to turn. Open the bleeder and fluid spurts; the wheel frees. The flexible hose has collapsed internally and is replaced with the caliper checked.