Car Tuning Drivetrain and Transmission Questions and Answers — Questions and Answers
Question 1: A customer has a rear-wheel-drive car primarily used for drifting. They want a differential that provides maximum, equal locking force during both acceleration and deceleration to maintain a predictable slide. Which type of limited-slip differential (LSD) is most suitable for this application?
- A 1-way LSD
- A 2-way LSD (Correct answer)
- A viscous LSD
- A Torsen-style LSD
Correct answer: A 2-way LSD
A 2-way LSD is designed to lock the wheels together under both acceleration and deceleration. This characteristic is ideal for drifting, as it provides consistent locking behavior when on and off the throttle, making it easier to initiate and control a slide.
Question 2: A tuner installs a very lightweight single-mass flywheel and a high-grip, unsprung ceramic clutch on a customer's street-driven car. What is the MOST likely negative side effect the customer will report during normal driving?
- Slower engine response when blipping the throttle
- A spongy and vague clutch pedal feel
- Significant increase in drivetrain noise and harsh gear engagement (Correct answer)
- Reduced engine braking effect
Correct answer: Significant increase in drivetrain noise and harsh gear engagement
Lightweight flywheels have less inertia to dampen engine vibrations, and unsprung clutch discs transmit more shock directly to the transmission. This combination often results in noticeable gear rattle, chatter, and much harsher, less forgiving clutch engagement, which can be difficult to manage in daily driving.
Question 3: Which of the following is the primary advantage of a Dual-Clutch Transmission (DCT) compared to a conventional torque converter automatic transmission in a high-performance application?
- Smoother operation at very low parking lot speeds
- Lower manufacturing cost and complexity
- Significantly reduced parasitic power loss and faster shift speeds (Correct answer)
- Greater torque multiplication from a standing start
Correct answer: Significantly reduced parasitic power loss and faster shift speeds
A DCT functions like two manual gearboxes in one, with clutches directly engaging the gears. This creates a direct mechanical connection that is more efficient and has less parasitic power loss than a torque converter. It also allows the next gear to be pre-selected, resulting in nearly instantaneous shifts.
Question 4: A tuner is preparing a car for a track with long straights where top speed is critical. The car currently accelerates very quickly but hits the rev limiter in top gear well before the end of the longest straight. What change to the final drive ratio would be appropriate?
- Installing a numerically higher final drive ratio (e.g., from 3.73:1 to 4.10:1)
- Installing a numerically lower final drive ratio (e.g., from 3.73:1 to 3.23:1) (Correct answer)
- Welding the differential to create a spool
- Increasing the clutch preload
Correct answer: Installing a numerically lower final drive ratio (e.g., from 3.73:1 to 3.23:1)
A numerically lower final drive ratio (also known as a 'taller' gear) reduces torque multiplication at the wheels but increases the theoretical top speed in each gear. This will allow the car to achieve a higher top speed on the long straights at the expense of some acceleration.
Question 5: When upgrading a high-horsepower manual transmission vehicle, what is the primary purpose of installing stronger, aftermarket axles?
- To reduce the vehicle's unsprung weight
- To change the final drive gear ratio
- To prevent failure from excessive torque transfer to the wheels
- To improve the smoothness of gear shifts (Correct answer)
Correct answer: To improve the smoothness of gear shifts
Factory axles are designed to handle the stock engine's torque output. When engine power is significantly increased, the stock axles can become a weak point and may twist or break under hard acceleration or launches. Upgraded axles are made from stronger materials to withstand this increased torsional load.
Question 6: What is the primary function of the springs located in the hub of a sprung-hub clutch disc?
- To increase the clamping force on the flywheel
- To ensure the clutch disc disengages completely
- To push the friction material against the pressure plate
- To dampen torsional vibrations and drivetrain shock (Correct answer)
Correct answer: To dampen torsional vibrations and drivetrain shock
The springs in the clutch hub are designed to absorb and dampen the shock and torsional vibrations that occur during clutch engagement and from the engine's power pulses. This results in a smoother power delivery, reduces stress on transmission components, and improves overall drivability.
Car Tuning Drivetrain and Transmission Questions and Answers
A customer has a rear-wheel-drive car primarily used for drifting.
They want a differential that provides maximum, equal locking force during both acceleration and deceleration to maintain a predictable slide.
Which type of limited-slip differential (LSD) is most suitable for this application?