310S Steering and Suspension 4 — Questions and Answers
Question 1: What is the purpose of the rebound stroke in a shock absorber?
- To compress the shock when hitting a bump
- To control the rate at which the suspension extends after compression, preventing the body from bouncing (Correct answer)
- To lower the vehicle ride height
- To increase spring rate during cornering
Correct answer: To control the rate at which the suspension extends after compression, preventing the body from bouncing
Rebound damping controls the speed at which the suspension extends after being compressed by a bump. Without adequate rebound control, the spring would continue to oscillate, causing the vehicle to bounce repeatedly.
Question 2: A vehicle equipped with electronic stability control (ESC) has the ESC warning light on. The steering angle sensor was recently replaced. What must be performed?
- A four-wheel alignment
- A steering angle sensor calibration (zero-point learning) (Correct answer)
- A brake fluid flush
- A tire pressure reset
Correct answer: A steering angle sensor calibration (zero-point learning)
After replacing the steering angle sensor, a calibration procedure must be performed so the ESC module knows the exact centre (straight-ahead) position. Without calibration, the system cannot accurately detect oversteer or understeer.
Question 3: What is the included angle in wheel alignment?
- The angle between the thrust line and the vehicle centreline
- The sum of the camber angle and the steering axis inclination (SAI) angle (Correct answer)
- The angle of the steering wheel from centre
- The difference between front and rear toe
Correct answer: The sum of the camber angle and the steering axis inclination (SAI) angle
The included angle is calculated by adding the camber angle to the SAI angle. It is used as a diagnostic angle — if SAI is correct but the included angle is wrong, the steering knuckle is likely bent.
Question 4: What causes a memory steer condition (the vehicle pulls in whichever direction it was last turned)?
- Unequal tire pressures
- Binding in the steering column, upper strut mounts, or ball joints preventing the steering from returning to centre (Correct answer)
- A worn power steering pump
- Incorrect rear toe alignment
Correct answer: Binding in the steering column, upper strut mounts, or ball joints preventing the steering from returning to centre
Memory steer occurs when friction or binding in steering/suspension components (worn upper strut bearing plates, binding ball joints, or tight steering column joints) prevents the steering from freely returning to centre.
Question 5: What is the purpose of the air suspension system's ride height sensors?
- To measure tire pressure
- To monitor vehicle height at each corner and signal the control module to adjust air spring pressure to maintain proper ride height (Correct answer)
- To detect wheel speed for ABS
- To measure body roll during cornering
Correct answer: To monitor vehicle height at each corner and signal the control module to adjust air spring pressure to maintain proper ride height
Ride height sensors (typically rotary position sensors on the suspension linkage) report vehicle height to the air suspension module, which adds or releases air from the springs to maintain the target ride height under varying loads.
Question 6: A technician is performing a bounce test on the vehicle. The body continues to bounce more than two times after pushing down on the corner. What does this indicate?
- Normal shock absorber operation
- A worn shock absorber or strut requiring replacement (Correct answer)
- Overinflated tires
- A weak coil spring
Correct answer: A worn shock absorber or strut requiring replacement
A properly functioning shock absorber should stop the body motion within 1-2 oscillations. Continued bouncing indicates the damper has lost its ability to control spring oscillation and needs replacement.
310S Steering and Suspension 4
What is the purpose of the rebound stroke in a shock absorber?