stock 2001 4l60 shift timing

[Cheif]

does anyone know what is a safe shift time for a stock 4l60? It's values are .3 sec. currently. can I set this to zero without doing damage? I use the truck for towing a 5500lb travel trailer and I'm looking to make my shifts as firm and quick as I can to keep the heat down. How much torque can a stock tcc hold? can I keep it locked up under full throttle?

[almostfast]

I have read that you can go down to .150, but the guy that wrote the article didnt seem too sure, so I personally wouldnt go below .250.

the rest of the questions I have no Idea. free bump!

[Braemerz28]

I drove my 2000 Sonoma with the shift times set to zero for about 10k miles with no issues.
The higher torque cells in my Trailblazer SS are set to .200 from the factory so that setting isn't unheard of either.
You have a heavier truck, but this setting alone probably won't hurt you too much unless you've also altered other settings that could be more damaging.

What will happen is the adaptives will see the zero number you commanded and look at the other tables to increase the pressures, etc to get as close as they can to that commanded Zero time. But, just due to the fact that there are fluids and clutches and such that take time to move, you will never truly get to a Zero shift time. In the same manner, you could have set the shift times to .010 and the adaptives would do basically the same thing since it is physically impossible to get that low. There is some min shift time that your specific trans is capable of due to its make-up and life to this point. If you command anything lower than that, you may as well set it to Zero.

The adaptives are also limited by the other values you have set such as pressures. Let's say you have left your pressure tables stock. The adaptives will use the biggest number in these stock tables. This might get you to a .250 shift time or something. Now, if you go into the shift pressure tables and allow more pressure, the adaptives can now use more of that to allow you to get down to a .200 shift time, again depending on wear and other things in your trans. Eventually if you keep dpoing this, you will reach the limits of the trans - maybe no more pressure available, maybe just physically impossible to shift any faster, maybe clutches worn, maybe you blow it up, etc. This is why folks say to take things in small increments when adjusting pressures so that you can inch up on the shift feel you want without jumping to a dangerous setting.

At least that's my take on it. There are some better experts out there who might also chinme in.

As for keeping the TCC locked under full throttle, that just seems like a bad idea to me. You'll end up frying the converter clutch. The reason they unlock is to allow the fluid to do the slipping insead of the clutch. Yes it heats up, but that's why you get an aux trans cooler if you really want, especially with a trailer that big. What you can also do is adjust your shift schedules so that the converter will lock and unlock at certain speeds in certain gears that might be more to your liking. For example, most stock tunes allow the converter to lock in 3rd gear which will allow you to run cooler (TCC locked), but with higher engine RPM to keep power up. I'd play with my 3rd and 4th gear shift schedules and TCC lock-up speeds if I were you. I'm guessing you have Tow/Haul mode so that would be a good place to start. They usually aren't that bad.

Good Luck!

[Cheif]

thanks for the advice guys, I was playing around in the editor and it looks like I couldn't keep the tcc locked up under full throttle if I wanted to. The tables just don't seem to give me that option. I raised my shift pressures and I have adjusted my shift points to keep it from shifting as much when I'm towing but I suspect my heat problems might be due to my truck being a 1/2 ton with 286000km on the original radiator, actually, original everything but the transfer case which does fine now that I change the autotrakII fluid every 2nd oil change. If you have a 4wd with the autotrak transfer case you might want to do the same especially if you have it set on auto during the winter. Completely off topic but a lot of people don't know about this even after they replace a transfer case. The dealer tends to leave that piece of information out.