310S Steering and Suspension 2 — Questions and Answers
Question 1: What is the purpose of the steering angle sensor (SAS) in a vehicle equipped with electronic stability control?
- To power the electric power steering motor
- To report the driver's intended direction to the stability control module for comparison with actual vehicle movement (Correct answer)
- To adjust the alignment angles automatically
- To activate the turn signal indicators
Correct answer: To report the driver's intended direction to the stability control module for comparison with actual vehicle movement
The SAS measures steering wheel position and rate of turn, providing the stability control system with data about the driver's intended direction. The system compares this with yaw rate and lateral acceleration to detect skids.
Question 2: A vehicle has a clunking noise from the front suspension when driving over bumps. What should be inspected first?
- The tire pressure
- Stabilizer bar end links and bushings, ball joints, and strut mounts (Correct answer)
- The wheel bearings
- The brake pads and rotors
Correct answer: Stabilizer bar end links and bushings, ball joints, and strut mounts
Clunking over bumps typically indicates worn suspension components with excessive play. Stabilizer bar end links and bushings, ball joints, and strut mounts are common failure points that develop play and clunk when loaded.
Question 3: What is the function of the rack and pinion steering gear?
- To amplify braking force
- To convert the rotational motion of the steering shaft into lateral movement that turns the front wheels (Correct answer)
- To absorb road shocks before they reach the steering wheel
- To maintain the front wheels in alignment
Correct answer: To convert the rotational motion of the steering shaft into lateral movement that turns the front wheels
The rack and pinion converts steering wheel rotation (via the pinion gear) into side-to-side linear motion of the rack, which is connected to the tie rods and steering knuckles to pivot the front wheels.
Question 4: What does the steering axis inclination (SAI) angle affect?
- Tire wear rate
- The vehicle's tendency to return to straight-ahead by creating a lifting effect that uses vehicle weight for steering returnability (Correct answer)
- Braking distance
- Suspension ride height
Correct answer: The vehicle's tendency to return to straight-ahead by creating a lifting effect that uses vehicle weight for steering returnability
SAI causes the vehicle to rise slightly when the wheels are turned from straight ahead. Vehicle weight acts as a force to return the steering to centre, complementing the caster angle for steering returnability.
Question 5: What is the primary cause of steering wheel shimmy at 80-100 km/h?
- Low power steering fluid
- Wheel and tire imbalance or a bent wheel (Correct answer)
- Worn tie rod ends
- Loose steering gear mounting bolts
Correct answer: Wheel and tire imbalance or a bent wheel
Steering shimmy at a specific highway speed is most commonly caused by wheel/tire imbalance. An imbalanced wheel generates centrifugal force that oscillates the tire and transmits vibration through the steering linkage.
Question 6: What is the purpose of the jounce bumper (bump stop) in the suspension system?
- To increase ride comfort during normal driving
- To prevent metal-to-metal contact when the suspension fully compresses (Correct answer)
- To adjust the ride height of the vehicle
- To support the coil spring
Correct answer: To prevent metal-to-metal contact when the suspension fully compresses
The jounce bumper is a rubber or urethane cushion that contacts the frame or body when the suspension reaches full compression (jounce), preventing damaging metal-to-metal impact and controlling the compression limit.
310S Steering and Suspension 2
What is the purpose of the steering angle sensor (SAS) in a vehicle equipped with electronic stability control?