Embrayage de convertisseur usé

The friction lining of the lock-up clutch inside the torque converter, worn to the point where it can no longer hold.

It is a clutch that lives inside a sealed steel doughnut, which shapes everything about diagnosing and repairing it: it cannot be inspected, and it cannot be replaced on its own. The repair is a torque converter, and reaching it means removing the transmission.

So it should be the conclusion, not the assumption. A shudder or a slipping lock-up is far more often degraded fluid or a solenoid, both of which are a fraction of the cost — and the fluid is worth doing first even when the converter turns out to be at fault, because worn lining is one of the things that contaminated it.

How it wears is heat and slip. Controlled slip is normal and designed for, but it puts the lining under continuous load; a cooling fault, a tired solenoid or old fluid turns designed slip into destructive slip.

A worn lock-up clutch also sheds material into the fluid, and that material reaches the valve body and the solenoids. Which is why converter failures so often arrive with a list of unrelated-looking solenoid codes — the debris got there first.