4l80e questions

[big dan]

Im considering a 4l80e for a truck Im working on that will be used as a dd/work truck/tow rig and Ive been doing some research on wiring and computer controls and ran accross a kit to modify the tranny for use of a vaccum modulator for shifting control.

I am not fond of additional computer controls and wiring so this kit is somewhat appealing and since the tranny will initially be connected to my carbureted motor it is even more appealing to do away with the computer. However I do not want to limit the performance of the transmission so I am not opposed to learning the electronics especially since I plan on an ls swap in the future.

So I would like some opinions on the usage of this kit as opposed to using the electronic controls.

Two things Im concerned with are downshifting and tc lockup. I know that with the 700r4s you could wire up the tc lockup with a switch and control it manually and I assume that you can do the same with this tranny correct?

And as far as downshifting goes, Im guessing that there is no downshift cable available since this tranny was originally meant to be computer controlled so are there any bad effects that may be caused by manual downshifting?

Seems like I have read all of this information here before but cant seem to find it again so any info that you can provide will be apprectiated.

 

[Cornfield creations]

This was a good write up. There is a stand alone controller for them.

http://coloradok5.com/forums/showthread.php?t=268551&highlight=4l80e&page=5

 

[sweetk30]

also try this one. simple to hook up and program by the looks of it. and cheeper also than tci .

few members here have it. not heard any bad on it also.

http://www.optishift.com/index.shtml

and ultimate 4l80-e to tcase thread. http://coloradok5.com/forums/showthread.php?t=166233&highlight=4l80-e

heard lots of guys talk about full man 4l80 kits. but never heard any farther than that. thay tend to just do stand alone kit and kep it full auto.

 

[big dan]

Totally forgot that there were stand alone controlers for this. Thanks for the info.

And thanks for the t-case thread sweetk30, that should prove useful as well.

 

[folkenheath]

Yes you can wire it to lockup the torque converter with a switch. You can also wire it to be full manual as well with no internal modifications (there are also companies that sell harnesses for that too) Or you could wire it to shift with buttons. There are only two solenoids that control the shifting. The force motor controls the line pressure, but if you leave it disconnected it defaults to the firmest stock shifting which is fine with teh trans if it's fine with you. The TCC solenoid controls the torque converter, and is usually PWM actuated for smoother engagement, but using a switch just engages it a little harsher, no biggie. The good thing about external wiring (manul or buttons) is if you decide to use a computer later you just unplug the manual harness and plug in the computer harness and the trans will still shift fine.

That vacuum modulator just replaces the force motor to reduce the pressure at low engine load. Not really necessary unless you feel the trans is shifting too firm at low engine load. The vacuum modulator will still not control the solenoids.

Manual downshifting will engage the bands for engine braking, which is not a problem unless you do this repeatedly to slow the engine down from a higher speed. If you are already in gear and it uses engine braking it doesn't matter, but the bands will wear much quicker with repeated manual downshifts for engine braking. 1st and 2nd use bands for engine braking, 3rd is direct so no band to worry about there. And obviously you can't downshift into 4th. If you are downshifting to accelerate then the clutch packs take the load so it's no big deal.

 

[big dan]

wow, excellent info. I did not realize that using the vaccum modulator kit meant full manual shifting.

Most likely I will be using one of the stand alone controllers as I dont want to deal with the manual shifting.