School Me: lock up torque converter

[nagal]

So what is the purpose of the lock up on a torque converter and when does the computer determine it should be used?

[goodtimes]

I assume you know what a torque converter is, and it's function...the "lock up" part of it refers to a clutch pack inside the torque converter that will eliminate any "slip" between the input and output sides of the torque converter. This does 2 things....reduces heat generated, and increases fuel economy. The PCM locks and unlocks the torque converter when certain conditions are met. Those conditions vary depending on make/model and operating conditions. But generally in high gear (either drive or overdrive), with light to moderate throttle position the torque converter will lock up.

[Fuel Rod]

Lock up torque converters make less waste heat so fluid is less taxed. Factory put them in to increase gas mileage in high way numbers. They usually always lock when you hit 45 mph. You have probably felt it. Now the third reason that I want to learn more about it is where we could manually switch it in and be able to push start the jeep with the automatic transmision.

[goodtimes]

Without the front pump turning, there will be no pressure to any of the clutch packs....so the output shaft will not be coupled to the input shaft. It is a relatively easy task to install a manual control switch to lock the torque convertor clutch up on demand (assuming it is a electrically driven clutch, not a hydraulically driven unit), but it won't help you push start a automatic.

[Dukes69]

Without the front pump turning, there will be no pressure to any of the clutch packs....so the output shaft will not be coupled to the input shaft. It is a relatively easy task to install a manual control switch to lock the torque convertor clutch up on demand (assuming it is a electrically driven clutch, not a hydraulically driven unit), but it won't help you push start a automatic.

Unless you have an external pump? :confused: