Torque converter lockup - comparisons?

[Bird]

Has anyone here done any back-to-back comparisons of torque converter lockup strategies and their effects on dyno numbers / 1/4 mile times, etc. I'm trying to gather data to come up with a decent enough strategy guide for better 1/4 times. If there is also data comparing leaving the t/c unlocked vs. locked, that would be helpful also.


TIA

Bird

[SILVER2000SVT]

At WOT like in a drag race condition The TC is not programmed to lock up until after reaching 3rd gear. (F.Y.I. at WOT the 99-00 trucks are factory programmed to lockup 0.00 secs after the 3rd gear shift and the 01-up are programmed to lockup 2.00 secs after the 3rd gear shift.) That would be the very last part of the 1/4 mile. So essentially variations in the TC lockup strategies would not effect drag racing times. The strategies the tuners play with only affect part throttle lock up in 1st and second gears.

Unless you do what I've done...

As far as I I've been able to tell I'm the only one to have tried to lock the TC up in a gear prior to the shift into 3rd at WOT. The computer couldn't be programmed to do it. The tables only allowed part throttle changes. I had to do it with the output of my WBC module and commanded the TCC to lockup by using a secondary relay.

The results were anything but pleasant. I didn't get any error codes but the transmission really freaked out. The best way to describe what happened is that the transmission basically starting at 4500rpms would shift back and forward between 2nd and 3rd about 3-4 times before finally staying in 3rd.

I stopped my testing before I could do any damage.
Not really sure what going on but I have 2 theorys:

First: When the TC tried to lock up, the calculated Engine load would change and the PCM would upshift too soon before the redline, but as soon as the upshift occured it would see too high of a calculated load and would down shift back to second.


My other theory which would be that the very reason Ford didn't allow the TCC to be locked up in 1st and 2nd gears during WOT is that there is not enough transmission fluid pressure and volume at the lower operating speed to handle the additional requirements of the TC clutch in addition to the other transmission functions. It takes a lot of fluid energy to carry out the functions of a transmission shift, It will also take a lot of fluid energy to lock up the TCC. Maybe there is not enough fluid energy to do both without something giving in. Maybe that's the reason the factory programming locks up after the 3rd gear shift so it doesn't have to hold during 1st-2nd or 2nd-3rd shifts.

[Tex Arcana]

It will also take a lot of fluid energy to lock up the TCC.

The only problem with that is the lockup is an electromagnetic clutch, iirc. My ex-brother-in-law used to activate his lockup with a light switch--granted, it was a mid-70's GMC truck with a later model transmission, but the concept was the same, taking out the slop from the torque convertor when it wasn't needed.

If anything, I'm thinking that, if the lockup can't handle the load in certain conditions, it's programmed to not lock in those conditions. don't know, just speculating.

If you REALLY want to test this, find the activation wire for the lockup, and do it manually, and see what happens. Just don't send me the bill, I assume no responsibility for the blowup. :tongue:

[L8 APEX]

Tex, once again you are polluting the internet with your ignorance. Converter clutches are applied with fluid there are no wires or coils inside of a converter. There is a small TCC colenoid in the valve body that sends fluid to the converter clutch via a passange inside the input shaft.

[G'Lightning]

Tex, once again you are polluting the internet with your ignorance. Converter clutches are applied with fluid there are no wires or coils inside of a converter. There is a small TCC colenoid in the valve body that sends fluid to the converter clutch via a passange inside the input shaft.:beer: :beer: :tu:

[WA 2 FST]

In theory, I'd think for ideal trap speeds _and_ ET's you'd want the TC locking up as soon as you get into 3rd (1:1 ratio). You're already on down the track aways (this will depend on how fast your truck is, of course) and an unlocked converter at these speeds/acceleration rates will only create more parasitic drag.

I know the GN guys will set up their 200R4 trannies to lock up in 3rd and they will often pick up 2-4mph in trap speeds (and a little ET as well) by doing this.

If the '01+ programming has the converter unlocked once the trans shifts into 3rd for 2 full seconds, then I believe there is something to be gained by shortening that delay time.

[Tex Arcana]

Tex, once again you are polluting the internet with your ignorance. Converter clutches are applied with fluid there are no wires or coils inside of a converter. There is a small TCC Solenoid in the valve body that sends fluid to the converter clutch via a passange inside the input shaft.

Unlike others that we all know:rolleyes:, I've got the balls to admit my ignorance, to wit:

I STAND CORRECTED.

I've got some experience with electromagnetic plate clutches, and I know how strong they can get, so I assumed that the lockup setup was basically the same. This is what I get for assuming, of course; but I do appreciated being corrected.

Which brings us back to the original issue, Terry: why the hell doesn't it work? Please, banish our ignorance on the subject. :tongue: