I did a search and read a ton. I'm not asking how a stall/torque converter works, but I want to know how it locks up. Some people say they have a toggle switch and others have it programmed into the computer to lock at a certain RPM. Can you have both? How does that work? I know what a converter does when it locks, but how does it lock? Are there wires somewhere in the tranny/converter that I'm not aware of? I want to know how it locks up, (NOT WHAT HAPPENS WHEN IT DOES) just how it can be locked up, or what makes it lock up.

 

The pressure plate and damper assembly of the lock-up mechanism is essentially the same as a MT clutch. To achieve lock-up, fluid pressure is released between the cover and the pressure plate allowing the pressure plate to move forward and lock to the machined surface on the cover. The fliud flow is controlled by a solenoid in the tranny. The solenoid receives a signal from the PCM and opens a passage in the valve body. Hydraulic fluid pressure applies the lock up clutch. When the signal stops, the solenoid closes the valve and pressure is relieved leading to disengagement.

If you want to have manual lock up, you just need to identify the wire in the tranny harness that controls lock up and install a switch.

Rich

 

Oh, so the transmission already has an automatic lock up? Do you know at what speed/rpm/gear that happens? If I installed a switch could I still have the computer engage/disengage it too?

 

I know you can on 700r4's don't know if the same applies to a 4l60e....

 

Can the speed/rpm/gear that the convertor locks up at be programed into the PCM?

 

Yes.

Rich

 

Do you know if the PCM already has them programmed in?

I would assume so, otherwise how would people ever get milage with autos? It would slip all the time no matter the size, even a little bit, and locking it would obviously make it have better milage.

 

 

Hmmm, interesting. To the top!

 

No one knows if the PCM already has lock up programmed into it forsure?

 

Yes, the PCM controls converter lockup based on rpm, tps, etc.

Rich

 

Suppose you wouldn't know at what rpm/gear/speed that is?

I am looking at getting a 3200/3500 stall, and I don't want it to lock up when it should be unlocked, and vise versa.

 

It's based on multiple inputs, like I said. TPS, RPM, MPH, gear, MAF, maybe others. So, it's not like at x rpm it locks and at y it unlocks. Once it is locked up, you converter will have no stall speed, or if you prefer to think of it that way, a stall speed of zero. The normal problem of having a converter stalling higher than your cruise rpm is obviated with a lock up converter. Once it's locked up, the stall speed becomes irrelevant.

Am I getting your question?

Rich

 

Not really...

I know it goes by a lot of sensors and inputs, but I was wondering if you knew at what input it decides to lock up. Also if changing to an almost double than stock converter would cause any side effects that I should look out for. I read a post saying sometimes the RPM jumps and the car acts like it stalls??? Why would that be? Does it lock the converter up a little too early maybe?

 

The fact that a high stall LU converter has to withstand much more torque / friction, ect. when it is applied since there is a greater RPM difference between locked and unlocked than a stock stall speed converter creates a need for PCM programming that will apply the converter clutch at higher RPM / speed and at less of a TPS value. The stock programming will not yeild the proper potential of the high stall and premature TC clutch failure will result from operating in this way {ask me how I know this?} . In my opinion, if PCM values are not going to be changed in order to work properly with the higher stall, I would suggest using a manual switch in order to lock the converter at a point that will increase it's life and also preform correctly as far as lock points are concered.
The tranny will not like the stock lock-up points either with a high stall converter since the actual input shaft RPM will be much lower than desired to execute proper shifting although the converter will be turning an acceptable speed.
It will work, for a while, but flashing the PCM with a program designed for a high stall converter or using manual apply will increase both performance and longevity.