6L90 Torque Converter Failure Mitigation

[Dutch]

Got in a playful argument about this.

I knew for a while a common failure of the 6L80s and 90s was for the torque converter to eventually shave itself.
A friend of mine in a high volume transmission shop sees this failure all the time - but unless they were fragrantly abused/neglected or had some QC issue they always had >250k miles on them when they went.
I believed there wasn't much you can do to mitigate this problem in software aside from not locking the TCC too early, not raise the pressures, and not have it slip at 30-50 RPM when its locked.
Whenever this comes up I just recommend regular fluid/filter changes, or if they're loosing sleep about it, have a reputable shop rebuild the damn thing with upgraded parts from sonnex, transgo, etc.

For normal driving I leave the TCC unlocked until 4th gear, reduce slip speeds under load to 0 while allowing 5-10rpm at low torque, and make an effort to keep the trans from shifting too frequently.
For towing I start to lock the TCC in 3rd gear, or 2nd if their tire/gearing setup is terrible, to avoid overheating when pulling up steep hills.

Common practice here seems to be leaving the TCC unlocked until 5th/6th gear.
The person I had this playful argument with believed this is "the secret to saving these transmissions".

While I'm sure there was a healthy amount of sarcasm behind that statement, it makes a good discussion point:

When you tune a customer who has a truck with a 6L80/90, do you do anything special specifically to prevent early failure of the converter? (besides disabling DoD on the 6L80s)
Is it really necessary to leave the TC unlocked all the way to 6th gear?
What do you tell the customer when they bring this up?

[5FDP]

I just disable the converter on basically everything for gears 1-4. Then raise the shift mph for 5th and 6th.

[Tfoggy]

I've tuned my 6L80E to my exact taste... It's built with all top quality components and a better than stock TC Clutch. I tow with it...
I've upscaled all my upshifts several mph.. Only Lock TC in 4th-6th so I can still get decent mpg in a Yukon
Set the "slip" down to 4ish in 4th gear and 0-2 ish in 5th and 6th...
Got it so I don't "have" to use my tapshift.. It'll do what I want on it's own now
It's still a work in process whenever I encounter diff situations, then a little bit of tweaking is in order

[Dutch]

What fluid temperatures do you see in stop-and-go traffic on hot days, or when towing up hills at low speeds?
Do customers tend to already have larger coolers, deeper pans, etc?

[alabastarbastard]

.......

[alabastarbastard]

i followed the tuning school gm trans booklet, i havent completed everything in it but it woke up the trans alot.. you really need to data log your trans with the correct PIDS to monitor slip in all gears and slip in the converter.

my base temp on stock 6l80 was 185-220 F
thermostat delete and 175 engine t-stat, and 1-3rd gear tcc disable =145-150F

next the ramp-in time and added 5-8% pressure increase to the clutches, I am now seeing 120-132 on the highway and stop and go traffic mild throttle , not aggressive driving. i can still sense some slip in the 2,3,4th gears under WOT , so i will have to tight those up next.

I haven't even installed a trans cooler, not sure I need too

[HawkZ28]

We had at converter take out my wifes Escalade earlier this year. About 130k I think. She doesn't drive remotely like what I'd call abuse, aside from bringing it home with the low fuel light on, though she has a heavier foot than me. Only adjustments I'd made to hers were shift times, line pressure, and zeroing out TCC slip.

i've used the Bluecat tool a few times now and love it. Get's it 95% of the way there, and remaining 5% is adjust for personal taste. Haven't done it on my current Sierra yet but started a tune to flash after I get some other issues worked out.

I swear by coolers. I have a B&M Supercooler (Long) on my Sierra- it's the model that's 12x12x1.5. Even sitting behind the intercooler, my temps rarely break 120 in town on hot days- this time of year I'm lucky to break 90-110. It takes 3-4 miles of highway driving to warm up enough for the TCC to lock. I have a Fluidyne on my 4L60E/Colorado that rarely breaks 120* in town. Got 300k+ out of the last transmission in that truck (currently 420XXX on the odometer) with the cooler.

[NotSure]

Read up on TCC Regulator Offset adjustments, just zeroing desired tcc slip will not stop it from slipping. But dont go crazy with it, as too much pressure can cause mechanical problems as well.

[village_idiot]

Most of what everybody above has said about the normal settings, but I still live by heat kills them...

Delete the trans thermostat
Add a BIG trans cooler, and run it not inline with the radiator (so as to not share heat transfer from the engine coolant)
Throw a 180 engine stat in it
Lower engine fan temp settings accordingly with the 180

Heat transfers a lot more than people give a lot of thought to usually. You will usually notice an A/C system perform better after the above (condenser has less heat in it)

[HawkZ28]

Read up on TCC Regulator Offset adjustments, just zeroing desired tcc slip will not stop it from slipping. But dont go crazy with it, as too much pressure can cause mechanical problems as well.

I recall reading up on it and doing some adjustments. It's one of the parameters that's amazing the difference small changes make, whether adjusting offset or pressure. Definite balancing act.