Locking torque converter, difference from 4th gen to 5th gen?
 

I have a 99 SE-L, my mom has an 02 GLE. Here's what I notice about the 2 trannys.

In my 99, the Torque Converter will unlock as soon as I step on the brake pedal.

In my mom's 02, the Torque Converter stays locked when I step on the brake pedal.

Personally I'd rather mine stay locked too. Makes no sence if I'm crusing at 60MPH, tap the brake to slow slightly and the converter unlocks. It should stay locked until I step on the gas harder or slow to under 31MPH. (Thats the min. speed the converter will lock at)

Anybody else ever notice this difference in the 4th to 5th gen trannys?

I'm wondering if there is a wire the goes to the ECU or tranny controller that can be cut to disable the unlocking when the brake is applied.

Neither car has a lockup t.c.

Someone needs to do their homework.

All Automatic trannys in 3rd, 4th and 5th gen Maximas have locking Torque converters.

Somebody correct me if I'm wrong with the 3rd gen.

Back to the top for today :)

can anyone fill me in on what exactly is going on when the torque converter stays locked?

thanks

Your automatic. . .sortof . . . becomes a manual. With the TC locked, your tranny now produces direct connection between engine and wheels, no longer relying on the fluid coupling connection in the torque converter.

DW

The operation of the torque converter is controlled by the computer or PCM as it is called in GM vehicles.

For those who don't really understand what a torque converter is, maybe this will help.

It is basically just a fluid coupling and some clutches. If you had a direct drive between the engine and tranny, it would shift hard, drive hard.
Two electric fans are an example. Face the fans toward each other. Turn one on and leave the other off. The fan that is on is the engine side, the engine turns this fan, the fan that is unplugged, is the tranny side.

The fan that is running will force air (or fluid) over the blades of the other fan and cause it to turn, which is a way to transfer power smoothly between the engine and the tranny. Throw in a lockup clutch, much like brake shoes, for the tranny lockup, and you have a lockup converter. When you reach higher speeds as determined by the computer, where the torque varies much less than at low speeds, you can "lock up" the converter, which means you engage a clutch, and then the converter acts as a "solid drive shaft" for lack of a better term. The engine and TC are both spinning at the same speed, which is more efficient, but only really useful at higher RPMs/speeds. Which is why if you floor it w/the TC locked, you will notice the RPMs up just a little at first (TC unlocks) and then they jump up a lot when the tranny kicks down.

Well, in a real torque converter there is a round steel ring with vanes called the "stator" between the two fans that helps reduce that leakage and improve efficiency. Sometimes this stator is in two, or even three, pieces to improve efficiency even more.

Also, traditionally people years ago began calling two fans inside the torque converter special names.

The fan attached to the engine was named the pump. That can be confusing since there is another entirely separate unit inside the transmission case that pressurizes lubrication oil and is called the "oil pump."

The fan attached to the shaft of the transmission is traditionally called the impeller.