ASE G1 Auto Maintenance and Light RepairAutomatic Transmission/TransaxleMedium
A vehicle with an automatic transmission exhibits a shudder or vibration during acceleration, particularly when the torque converter is commanded to lock up. This symptom is most noticeable between 35-50 mph. What is the most probable cause?
- AA faulty torque converter clutch (TCC).
- BA worn universal joint (U-joint) in the driveshaft.
- CLow transmission fluid pressure due to a failing pump.
- DAn imbalance in the wheels or tires.
Show answer & explanationAnswer & explanation
Correct answer: A. A faulty torque converter clutch (TCC).
A shudder or vibration specifically during torque converter lock-up, often at highway speeds, is a classic symptom of a faulty torque converter clutch (TCC). The TCC is designed to create a direct mechanical link for efficiency, and if it's worn or failing, it can't engage smoothly, causing a shudder.
Why the other options are wrong
- B. Worn U-joints typically cause clunking during gear engagement or acceleration/deceleration, not a specific shudder during TCC lock-up.
- C. Low transmission fluid pressure would likely cause slipping, delayed shifts, or no engagement, not typically a shudder specifically during TCC lock-up.
- D. Wheel/tire imbalance causes vibration that increases with speed, but it's usually constant and not specifically tied to TCC lock-up.
Torque Converter Shudder
Torque converter shudder is a vibration or pulsation felt through the vehicle, typically during the engagement or disengagement of the torque converter clutch (TCC), often at specific speeds.
- Often mistaken for engine misfire.
- Can be caused by worn TCC friction material or hydraulic control issues.
- Requires specific diagnostic tests to confirm.
Memory trick: Torque Converter Clutch Chatter: TCC is the cause of the shudder.