310S Drivetrain and Transmission 2 — Questions and Answers
Question 1: What is the purpose of the torque converter lock-up clutch?
- To prevent the torque converter from spinning at idle
- To mechanically lock the impeller and turbine together at cruising speeds, eliminating fluid slippage for improved fuel efficiency (Correct answer)
- To increase torque multiplication during acceleration
- To engage reverse gear
Correct answer: To mechanically lock the impeller and turbine together at cruising speeds, eliminating fluid slippage for improved fuel efficiency
At cruising speeds, the lock-up clutch mechanically connects the impeller (pump) and turbine, creating a direct 1:1 drive. This eliminates the 2-5% fluid slippage inherent in the hydraulic coupling, improving fuel economy.
Question 2: What is the purpose of synchronizers in a manual transmission?
- To lock the transmission in gear
- To match the speed of the gear and the synchronizer hub before engagement, allowing smooth shifting (Correct answer)
- To lubricate the gear teeth during meshing
- To prevent reverse gear from engaging while moving forward
Correct answer: To match the speed of the gear and the synchronizer hub before engagement, allowing smooth shifting
Synchronizers use friction rings (blocking rings) to match the rotational speed of the selected gear to the hub/shaft speed before the engagement sleeve locks them together, preventing gear clash during shifting.
Question 3: A vehicle with an automatic transmission exhibits a shudder at light throttle between 55-70 km/h. What is the most likely cause?
- Worn tires
- Torque converter clutch shudder caused by worn friction material or contaminated fluid (Correct answer)
- A misfiring engine
- Unbalanced driveshaft
Correct answer: Torque converter clutch shudder caused by worn friction material or contaminated fluid
Torque converter lock-up clutch shudder occurs when the clutch cannot engage smoothly, typically due to worn friction material, degraded ATF, or contaminated fluid. It's most noticeable at light throttle during lock-up engagement speeds.
Question 4: What is the purpose of the transfer case in a four-wheel-drive vehicle?
- To replace the transmission
- To receive power from the transmission and distribute it to both the front and rear axles (Correct answer)
- To lock the differential
- To provide additional gear reduction only
Correct answer: To receive power from the transmission and distribute it to both the front and rear axles
The transfer case is mounted behind the transmission and splits the driveline power between the front and rear axles. It typically includes a chain or gear drive and may offer high and low range selections.
Question 5: What causes a manual transmission to pop out of gear?
- Low transmission fluid level
- Worn synchronizers, shift fork, detent mechanism, or gear engagement teeth (Correct answer)
- A dragging clutch
- Incorrect shift knob installation
Correct answer: Worn synchronizers, shift fork, detent mechanism, or gear engagement teeth
Popping out of gear is caused by worn detent springs/balls that fail to hold the shift fork in position, worn shift fork pads, worn engagement teeth on the gear or sleeve, or worn synchronizer hub slots.
Question 6: What is the function of the CV joint boot?
- To dampen driveline vibration
- To contain grease and protect the CV joint from water, dirt, and debris contamination (Correct answer)
- To limit the articulation angle of the joint
- To cool the CV joint during operation
Correct answer: To contain grease and protect the CV joint from water, dirt, and debris contamination
The CV joint boot is a flexible rubber or thermoplastic cover that seals the CV joint, keeping the special grease inside and preventing contaminants from entering. A torn boot quickly leads to joint failure.
310S Drivetrain and Transmission 2
What is the purpose of the torque converter lock-up clutch?