Video: Lock-Up Torque Converters 101

This video covers the fundamental differences between lock-up and non lock-up torque converters, including a breakdown of the anatomy of a lock-up torque converter, and the advantages of using one. Check it out:

On this installment of Quick Flicks were going to address a question that we had on our previous torque converter video. The question was, what about lock-up converters? I think a lock-up converter in comparison to a standard converter is a little mysterious in the fact that it does operate a little differently than the standard torque converter does.

For most of us that have been building muscle cars or street rods, for the most part if we were using an automatic transmission, we were using the standard three-speed automatic in a lot of these applications. Most three-speed automatics use a standard non lock up converter. This means that your going to have a percentage of loss throughout the drivetrain with that converter because that converter does not have a lock up device in it, and that has always been the downfall to having an automatic transmission in any vehicle is the fact that you have somewhere between a five to 10 percentage drivetrain loss of power throughout that assembly.

Whereas in comparison if you go with a transmission that goes with a lock-up converter in it, you get that full transfer of power once the lock up piston engages inside that converter. This is becoming more and more relevant in builds today because more and more people are building vehicles for not just performance, but for fuel mileage as well, so they can go ahead and use more aggressive gearing on the street and they need that extra overdrive gear set in that transmission. We are seeing this mostly in the automatic overdrive world where those transmissions require a lock-up converter to operate correctly.

What’s happening with a lock-up converter is once that transmission senses a certain mile-per-hour, or a certain rpm, it’s going to go ahead and engage a lock-up piston that’s actually going to be on the back side of the converter against the turbine assembly. You’ll notice that on the input shaft assembly on that automatic overdrive transmission you will not have the standard two shafts that you have seen, there is actually going to be a third shaft that is really small, that is going to be the engagement unit for that piston assembly inside that converter. The benefits to this for the most part these days is that you have the ability to have a vehicle that is maybe aggressive on the street but has some race car manners at the same time, and what it does for you is once it reaches a certain speed, it locks that piston up and now you get better fuel mileage and at the same time the vehicle doesn’t seem like it has as aggressive gearing in it.

As seen in this image you will notice that a lock-up converter looks very similar to that of a regular non lock-up converter–it still maintains the standard impeller, turbine, and stator assembly, but it’s also going to add a lock-up piston device to go ahead and put it into lock-up mode when necessary.

Hopefully this video will clear up any questions you had about how lock-up torque converters operate. Feel free to leave comments or questions in any of these videos. See ya soon.