The ZF-8 has a lock up clutch. That's why it's so efficient. It uses the torque converter as a pump to match the speeds but then engages that clutch to have a 1

The ZF-8 has a lock up clutch. That's why it's so efficient. It uses the torque converter as a pump to match the speeds but then engages that clutch to have a 1-1 connection. No losses.