Braking, Steering and Suspension Systems
What the exam tests
Questions cover hydraulic braking, disc and drum brakes, ABS, steering geometry, rack-and-pinion steering, springs, shock absorbers and alignment angles.
Core rules
- Hydraulic pressure from the master cylinder operates calipers or wheel cylinders. Brake fluid is hygroscopic, so it must be changed to specification and never mixed with another DOT grade.
- Bleed brakes from the farthest wheel from the master cylinder, usually right rear, left rear, right front, left front, while keeping the reservoir full.
- Steering geometry includes camber, caster, toe and kingpin inclination. Incorrect toe wears tyres; incorrect caster affects straight-line stability.
- Suspension springs carry load; shock absorbers control bounce. Worn bushes and struts cause noise, uneven tyre wear and poor handling.
Worked example
A vehicle pulls to the right only when braking. Reasoning: a seized right caliper, collapsed brake hose, contaminated pad or unequal tyre pressure can cause this. Check tyre pressures first, then inspect both front brakes for drag and uneven wear. A pull while driving, not braking, points more to alignment or tyre conicity. The distinction prevents replacing the wrong parts.
Traps that cost marks
Opening a hot radiator or brake reservoir carelessly, using water in brake fluid, bleeding in the wrong order, and judging alignment by eye. Also do not test ABS by pumping the pedal; ABS operates automatically and requires diagnostic checks.