Steering, Suspension and Braking Systems
What the exam tests
This domain combines steering geometry, suspension types and braking performance. Expect questions on Ackermann steering, caster, camber, toe, leaf and coil suspension, hydraulic brakes, brake force and ABS.
Core rules and concepts
- Ackermann geometry makes inner and outer front wheels follow different radii. The inner wheel steers through a larger angle.
- Caster gives self-centring; camber affects tyre wear and cornering; toe controls straight-line stability and scrub.
- Suspension must support weight, absorb road shocks and keep tyres in contact with the road.
- Hydraulic brake force is transmitted by fluid. Force at the shoe or pad depends on pedal force, pedal ratio, master-cylinder area and wheel-cylinder area.
- ABS prevents wheel lock by modulating pressure, preserving steering control during hard braking.
Worked example
A car travelling at 54 km/h brakes at a steady 6 m/s². Convert speed: 54/3.6 = 15 m/s. Braking distance d = v²/(2a) = 15²/(2 × 6) = 18.75 m. If the driver's reaction time is 1 s, the car travels another 15 m before braking begins. Total stopping distance is about 33.75 m. This shows why speed and reaction time matter more than brake force alone.
Traps that cost marks
- Using km/h directly in the braking formula.
- Mixing toe-in with positive camber.
- Assuming ABS shortens every stop; it mainly preserves steering control.
- Ignoring brake fade from overheating.