Blasted2hell

iTrader: (2)

I can easily identify when my torque convertor is going into lock-up, but I was thinking about it the other day and I couldn't say I honestly knew when it should or shouldn't be doing it. I've got a general idea, but not a very good knowledge of it.

So I was hoping some of the tranny guys could explain to a novice like me the proper times for a torque convertor to go into lock up. The transmission in question is a 4L60e. If the torque convertor matters I'm running a Yank SS3200.

For instance if the car is in D...and your only doing about 35 so your still in 3rd, should the verter go into lock up? What about 2nd? I know it should in 4th, but should it wait till your up to a certain mph?

performabuilt

iTrader: (25)

All of this is determined by tuning , The TCC can lockup in 3RD and I have seen some cars that will lock in second, but basically the converter should lock at light throttle at cruising speeds and with the stock tune will do so in 3rd and 4th gears . As for the MPH the lockup occurs thats again totally PCM determined. Several things beside MPH determine lockup times, TPS,MAF,RPM,VSS

silver-mod-o

iTrader: (15)

I've posted this before... treat lockup as 6th gear in an M6 car... use it under cruise situations... when passing or accelerating, unlock the converter. mine locks in 4th @18% TPS above 50mph... at 43% it unlocks for passing... it stays locked while the CC is on. I have the unlock TPS set @ 43% so you have to deliberately give it some throttle to unlock... too low TPS and its annoying and will generate heat, not to mention wear out lock up clutches faster, too high TPS and it will seem to never unlock and want to feel boggy... Its a fine line and determined by your driving habits and what you like...

If you have any questions about how my individual setup works, let me know, I'll try to explain better.

melchoir

iTrader: (4)

Purely tune dependant. I removed 3rd gear lockup on my car as it was annoying, and have it locking up in 4th at low throttle at 35mph. On my car this is fine there is no lugging and I have plenty of low end power to accelerate the car. I believe 25-30% throttle will unlock it, I'd have to check.

silver-mod-o

iTrader: (15)

keep in mind I'm tuning a 3600 stall in a 4500lb 5.3L truck so throttle position and input are a little different than a LS1 car... same theories though.

Blasted2hell

iTrader: (2)

probably not too far off, my GTO with me in it is 4100lbs

Some good information, I'm seeing where preference comes into it. So I guess by what is being said, if your cruising down the highway on some long trip and it's not locked, that's kind of bad, considering if it was locked you'd be maintaing throttle postion and a rpm of about 2300-2500

But in 3rd gear this really isn't too much of a concern, only really 4th gear for driving at consistent speeds for x amount of time?

performabuilt

iTrader: (25)

Yes for reasons of heat generation its improtant he be locked up in 4th gear when cruising otherwise with the high stall speed RPM not transfered to motion is transfomed in to heat alot of it.

silver-mod-o

iTrader: (15)

unlocked, its a fluid coupling so there's slippage and in turn, heat generated. locked, its like a manual car in gear (basically)... 1:1 mechanical transfer...

12secSS

iTrader: (30)

From what I have gathered, you want it to lock up once the torque has leveled out in that particular gear. GM designed the lock up points for the best MPG, so making it unlock at the slightest throttle will reduce the MPGs. The way I setup the shift points and lock up points, based on the calculated torque, fuel mileage is preserved. Even on high stalled cars. Once the torque is no longer being generated, all you are doing is spending extra fuel. The OEM TCC lining can handle some throttle transition once locked, it is only when the rpms are climbing fast during WOT, that the TCC will have issues trying to apply and lock. A manual trans has a beefier clutch and can sustain this "abuse", but the TCC is not as big or strong to take this abuse, but as I said ... under part throttle conditions, it can handle upto 50% TPS in 4th gear (for example). Aftermarket units typically have larger TCC linings that have a better clamping force for increased rotational forces. Typically truck calibrations will have the TCC lock up in 2nd (Tow/Haul Mode), this is to reduce the overall heat generated by the extra load of a trailer. Passenger vehicles do not have this feature enabled from the factory, and are not expected to tow a trailer, so there is no reason to lock up the TCC in 2nd. Yes, trans shift point tuning is very personal, but with proper understanding of what a shift point and lock up operate, it can be done very easily. Currently I am working on an excel spreadsheet that can fill in these (automatic shift point and lock up) tables for you, based on a simple log.

Gilbert@Ace Racing

Hey Blasted...

In our conversation yesterday we discussed the fact that the converter would not lock up unless the ignition key was cycled. And that was pretty consistant based on the number of times you had experienced it. And it seemed as though it was not temp dependant as well.... is that still occuring or are you thinking it is operating as it was designed to? After reading your comments today, I would say it is in need of having the tune files adjusted for the different throttle position / rpm ratios with the new converter.

But after reading this thread I am getting somewhat of a different picture of the symptoms since the converter was upgraded. Glad to see you working through this, many enthusiasts will not take the time to try and understand an issue after mods are done... good for you.

That answer really is vehicle specific as mentioned earlier here in the thread. and the cool thing is you can have it tailored to your liking!

Give me a shout, I would like to discuss this with you again!

I will be in until about 7:00 p.m. (central) and then I'm off to the track to watch one of my customers run his car... new converter combination, looking for better 60' times.

g

Blasted2hell

iTrader: (2)

This has all been great information everyone. I realize now how much of it can be tailored to my liking and how much is needed for the health of the transmission/efficency of the car.

I really didn't mention any of my specific issues in this thread since I'm just trying to gain more of an accurate knowledge in regards to torque convertors before proceeding any further.

Yes my problem with lockup still appears to be linked to a key cycle, and not so much temperature, because the other day when leaving work, I just drove the car out of the parking garage, turned it off and then on while in neutral and it locked up just fine. It also unlocks just fine too, outside of the key cycle issue, and based on what everyone has stated here, I'd say my torque convertor operates perfectly, if not for having to key cycle it so that it decides to lock up at all. As others have stated, I think the only answer is driving it with a scanner on it before I key cycle it to see if the computer is commanding lockup at all, and if it is, possibly what's arguing with it.

performabuilt

iTrader: (25)

Glad your trans is doing well let me know if you need any information concerning this key cycling issue. Kinda sounds like and engine missfire issue maybe?

Blasted2hell

iTrader: (2)

I'm aware of misfires causing torque convertor issues, but the misfires going away due to a key cycle doesn't make sense to me. There's also no misfire code being thrown, and the car drives like a champ, shifts fine, just no lockup without a key cycle.

performabuilt

iTrader: (25)

Well the KEY cycle while it dosent clear codes does reset the PCM each time so was and idea