Torque Converter Lock/Unlock

[JohnDee68]

Hi,
I am trying to understand, so i can hopefully get to tune my transmission (4L40e) for my style of driving and requirement. Iron out a few glitches I feel so to speak with it at this point if I can possibly.
But before I mess with things, I best need to understand how a Torque Converter is actually meant to work in operation. I understand it is there to be able to allow and not allow fluid drive as required depending on motor loads, but I am unclear as to when one would want it to be fluid drive and when one would want it to be non fluid drive. As my logic is thinking it is best to have non fluid drive all the time like a manual gearbox, so there isn't any slipping which is really power loss in the drive. Or is the Torque Converter just the equivalent to a clutch and should only be Unlocked (fluid drive) for a few seconds at gear changes in the transmission?

I presume that if aiming for best economy from gear shifts and driving over varied speeds, it would be best to get in to TCC Lock as soon as possible would it not?

Can anyone try to explain this topic to me at all please? I would like to understand it so I can know what and how I would need to adjust things like TCC setting tables in TunerPro for best suiting my driving needs. While I also don't want to blow up the transmission either from overloading or something by accident.

[immortality]

There are a few good video on how torque converters work. They kinda work like a clutch and therefor must be working normally (as a fluid coupling) when stop/starting etc. Once moving you can lock the converter to gain efficiency but you need to take into consideration gear/speed as locking the converter may pull the engine down and possibly make the engine work harder.

It depends on what car/tune you are using also. For the ecotec models the software has TCC for 3rd and 4th but I believe in 11p it can lock the converter in 2nd as well. Holden liked to get the transmissions into 4th as quickly as possible in n/a applications and let the converter do all the work. On boosted applications (like the L67) they took a slightly different approach and had the transmission stay in 3rd longer and bring in TCC. I prefer this approach.

There are also options to allows transmission upshift or downshift with the converter locked although only some of the definitions have this.

[JohnDee68]

Immortality,
For me, a novice so to speak on autos. I guess it is hard to know whether it is the TCC or gear changing then that might be the issue I experience at times.
Relating to my VX Ecotec then, I presume the best for the TCC is to engage after gear change has occurred and the engine is under little or no load? As you say, 3rd and 4th gears. I personally feel and would like the car to go in to top gear as soon as possible once load has been reduced to some ideal level such as coasting. Then engage the TCC as to increase efficiency on top of gear change, would that be correct?

[delcowizzid]

That is exactly what holden did chased the tcc settings for emissions/economy targets. In vn vp it only locked up at 80 odd kmh and above and unlocked pretty easy by the time vx and vy were here they were sliding the lockup in slowly to slow the load on the engine for economy and shift feel they also run the tcc down at lower speed in 3rd.

[JohnDee68]

That is exactly what holden did chased the tcc settings for emissions/economy targets. In vn vp it only locked up at 80 odd kmh and above and unlocked pretty easy by the time vx and vy were here they were sliding the lockup in slowly to slow the load on the engine for economy and shift feel they also run the tcc down at lower speed in 3rd.

Thanks delcowizzid,
I am then guessing that as long as I keep the Lock at a higher speed than the Unlock in the tables relating to the gearing, I should be good as far as not blowing up the trans?

[delcowizzid]

If you don't labour it under the load and send all the convertor clutch material right through the box you should be fine it isn't a manual clutch that's made to have much load on it

[immortality]

It also helps to reduce the TCC PWM control for TCC lock. The factory slip into lock makes for a smooth ride but lots of wear and tear. To me it feels much better when TCC lock actually feels like it's going into the next gear.

[JohnDee68]

Thanks guys,
On the weekend I hope to have a play with the Lock and Unlock settings. While also a slight alteration to the Gear change speeds.
As I noticed in a few logs, the trans wasn't getting in to 4th gear at 60kmph, but more up near the 65kmph. Which is not good when driving along at 55-60kmph city driving.
I presume that even if in top gear, the gearbox through its PCM software, will cater and drop down gears still if required for overtaking etc.?

[immortality]

The speedo on the Commodore is calibrated to read fast.

[JohnDee68]

The speedo on the Commodore is calibrated to read fast.

Yeah, I notice it's not accurate as some. What is it that we change to fix that? is that adjustable via the VSS Ratio - Pulse/Rev Output Shaft setting in TunerPro do you know?