CAE Vehicle Dynamics & Powertrain 2 — Questions and Answers
Question 1: What is the primary purpose of a limited-slip differential (LSD) in a performance vehicle?
- Reduce fuel consumption during acceleration
- Transfer torque to the wheel with more traction when slip is detected (Correct answer)
- Increase ground clearance on uneven terrain
- Decouple the drivetrain during braking events
Correct answer: Transfer torque to the wheel with more traction when slip is detected
An LSD senses speed difference between driven wheels and biases torque toward the wheel with greater traction, reducing wheelspin.
Question 2: In a MacPherson strut suspension, which component provides the upper pivot point for the strut assembly?
- Ball joint at the lower control arm
- Strut bearing/mount at the top of the shock tower (Correct answer)
- Stabilizer bar end link
- Tie rod inner end
Correct answer: Strut bearing/mount at the top of the shock tower
The strut bearing mounted on the shock tower serves as the upper pivot, allowing the strut to rotate with steering inputs.
Question 3: Which powertrain configuration places both the engine and drive axle at the same end of the vehicle, sharing a common housing?
- Longitudinal front-engine rear-wheel drive
- Transaxle layout (Correct answer)
- Solid rear axle with Panhard rod
- De Dion tube arrangement
Correct answer: Transaxle layout
A transaxle combines the transmission and differential into one unit, typically used in front-wheel-drive and mid-engine rear-wheel-drive layouts.
Question 4: When a vehicle exhibits 'terminal oversteer,' what is happening to its handling behavior?
- The rear tires lose grip and the vehicle rotates excessively toward the turn (Correct answer)
- The front tires push wide and the vehicle understeers off the road
- The vehicle rides height increases causing instability
- The brake bias shifts rearward causing rear lockup
Correct answer: The rear tires lose grip and the vehicle rotates excessively toward the turn
Terminal oversteer means the rear axle loses lateral grip, causing the vehicle to spin — a self-reinforcing, hard-to-correct condition.
Question 5: What does the term 'wheel rate' refer to in suspension engineering?
- The rotational speed of the wheel in RPM
- The effective spring rate measured at the wheel contact patch (Correct answer)
- The angular rate of steering input per degree of lateral acceleration
- The rate at which brake torque builds at the rotor
Correct answer: The effective spring rate measured at the wheel contact patch
Wheel rate accounts for the installation ratio (motion ratio) of the spring, giving the actual spring force per unit of wheel displacement.
Question 6: In an automatic transmission, what is the function of the torque converter lockup clutch?
- Prevent transmission fluid from overheating during towing
- Mechanically connect the turbine to the pump to eliminate slip at cruise speeds (Correct answer)
- Engage park pawl when the vehicle is stationary
- Modulate shift pressure during kickdown events
Correct answer: Mechanically connect the turbine to the pump to eliminate slip at cruise speeds
The lockup clutch bypasses fluid coupling slip, creating a direct mechanical link that improves fuel economy at steady-state cruise.
Question 7: Which of the following best describes 'roll stiffness' in a vehicle chassis?
- The resistance of the chassis to longitudinal bending under braking loads
- The resistance of the suspension to body roll per degree of chassis lean (Correct answer)
- The stiffness of engine mounts under high-torque conditions
- The torsional rigidity of the driveshaft under full throttle
Correct answer: The resistance of the suspension to body roll per degree of chassis lean
Roll stiffness (Nm/degree) quantifies how strongly the suspension resists body lean during cornering, influenced by spring rates and anti-roll bar stiffness.
CAE Vehicle Dynamics & Powertrain 2
What is the primary purpose of a limited-slip differential (LSD) in a performance vehicle?