i know what a torque converter is and how it works but i dont understand lockup and nonlockup also what is a stall rate and what does it do say a 2000rpm stall

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CHRIS
1983 firebird transam
edelbrock performer rpm intake 360*k&n intake 160 theroostat gitting trans raced up and lots and lots of plans 4 the future

 

To understand a Torque Converter think of it as a hydraulic slipping clutch. It allows you to sit at a light in gear W/O stalling out but as you step on the gas it 'engages' and drives the tranny. The stall speed is when the converter cannot slip anymore without driving the car or limit how high the RPM will go W/O moving the car. Inside the converter is an impeller that drives the Input Shaft of the tranny and another that is driven by the engine. At a standstill with your foot mashed down on the gas pedal you will be at stall speed, that is the engine will be driving the converter at, let's say 2000 RPM but the input shaft (and the driven impeller) will be stopped. As you begin moving so does the Input Shaft and as the R's get high enough the two impellers will be close to the same speed (coupling speed) but there will be a little (or allot depending on the efficiency of the converter) slip. This is where the L/U clutch comes in. Inside the converter is a clutch disc that when applied locks the Driven Impeller to the Converter housing providing 100% power transfer.

The proper stall speed depends completely on the power band of your engine. This means that if you have an engine that starts to "pull" at say, 2100 RPM and you have a 1600 stall converter, your performance off of the line will not be at it's best. On the other hand if you put in a 2400 or 3000 stall you will be wasting expensive power, since the converter won't be passing the maximum power to the tranny until later in the power band. In the example I used, a 2000 stall would be ideal since you will "flash" up a little bit on take off. You will then be at the optimum take off RPM. Sometimes too, people have the proper stall converter for the engine combo but have the wrong rear end gears to fully utilize the power.

[This message has been edited by transfixleo (edited September 30, 2001).]