Drivetrain and Transmission Flashcards

What is the purpose of the torque converter lock-up clutch?

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.

What is the purpose of synchronizers in a manual transmission?

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.

A vehicle with an automatic transmission exhibits a shudder at light throttle between 55-70 km/h. What is the most likely cause?

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.

What is the purpose of the transfer case in a four-wheel-drive vehicle?

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.

What causes a manual transmission to pop out of gear?

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.

What is the function of the CV joint boot?

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.