To improve fuel economy over decades a variety of changes have occurred to transmissions including the torque converter. To minimize converter slippage an array of lockup features has been implemented by the OEMs with varying results. One such system is the Toyota Flex-Lock lockup. Various drivability issues can arise if the system is not working correctly. Computer, converter,
Although one of the first lock-up torque converters to be used in an automatic transmission was in a Packard Ultramatic back in the fifties, lock-ups were just not that popular. Transmissions back then either used a fluid coupling or an “open” torque converter.