Could someone please explain to me exactly how a Torque Converter works. I would like to know its function, when it should lock/unlock and why. Also what is best for performance, locked or unlocked? For example what does it do at wide open throttle? Also what is the advantage/purpose of these manual lock up switches that guys run? Sorry so many questions, but I need help.

Thanks

 

Imagine 2 fans face to face; you turn one on. The other will start to turn. That's basically how a torque converter works, except that since it's fluid it couples much more tightly than the 2 fans ever will, and there's a stator in between the turbines, that redirects the fluid flow for particular effects (either a higher speed or a lower speed that the coupling between the input turbine and output turbine becomes nearly solid, for instance). When the 2 turbines are turning at different speeds, the power that's coming from the engine to turn the first one but that's not making it to the second one, goes into the fluid and heats it up; that's why you should always increase the trans fluid cooling when raising the stall speed of your converter.

The lockup is simply a friction clutch that bypasses the fluid coupling. So, when it's engaged, it's transmitting the power instead of the fluid. It unlocks at WOT because it's too weenie wih stock pressure behind it to survive with the full power of the motor on it; it will slip, in stock form, and burn up rapidly. However, with it locked up, that's a little more engine power that gets coupled to the wheels and not lost in the fluid.

 

Thank you very much, that helped a lot. So people run the manual lockup b/c it gives you a little more power by using the "friction clutch" instead of the fluid, but at the same time it is harder on the trans. and TCC?? Also would you mind explaining when the TCC should be locked and unlocked. Like it really should be unlocked at WOT, but what about cruising around town or on long highway drives?

Thanks again

 

Long highway drives, it should be locked up. That's what it's mostly there for: gas mileage.

Around town it doesn't matter so much.

 

Well, on a hunch, I checked out http://www.howstuffworks.com , and they cover torque convertors: http://www.howstuffworks.com/category.htm?cat=Transm At the bottom, click on "torque convertors". And for a laugh, on the last page of the "how torque convertors work", there's a link to the video. The guy sounds like he's not sure how a TC works either!

 

All torque converters will slip a little bit. A torque converter will slip the most when at very low rpms (below the stall speed). As the converter reaches it's stall speed it is considered to be in 1:1 but it is still slipping slightly. Most are under 8%. If the converter didn't slip at low rpm the engine would stall. It would be like driving a manual transmission in high gear and slowing down. If you don't step on the clutch the engine will stall.

By locking it up this slippage is eliminated. If the slip is eliminated then all the power going in will also come out. That's why mileage increases. The engine rpms will be less to produce the same amount of power through a locked up torque converter compared to a regular one.

I think the proper description of a torque converter is "A fluid coupler that transmits engine torque to the transmission"