locking TC in 4L80 questions

[Elroy]

i have a 1996 GMC sub 2500 4x4 w 7.4 and 4l80, towing about 5500 lbs , toyhauler, over 210K but it was probably rebuilt at 150K? before i bought it? fluid looks good for over 210K

i have the black bear traditional tune, MF exhaust ( new a couple weeks ago)

tires are 265/75/16 , 3.73 gear?

i towed the trailer 2000 miles last week from so-cal to near chicago

i notice that out west for the worst long climbs it doesnt want to pull 3rd all the way, shifts to 2nd, thinking of going 4.11

real question is that i see the TC lockup when i get out of the throttle, sometimes a stab at the gas unlocks it, sometimes it doesnt, am i going to have a problem here? ive heard the TC should stay unlocked towing or under 70?

i stay under 70mph towing, i can go 70 in 3rd at just under 3K

rpm climb a couple hundred when the TC unlocks and it pulls better uphill that way

sometimes im going 60 and stab the gas and it wont unlock , maybe if i really hit the gas, and other times it unlocks with alot less throttle

is this controlled by the computer alone or other factors like speed?

should i get the transgo shift kit?

 

[Elroy]

pic for attention, this was new mexico i think

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[RDF1]

TCC lock and unlock is controlled by Gear/MPH/throttle position algorithm.
Lower gears might would help some. Maybe not as much as you would like though.

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[Tavi]

You want the TC locked as much as possible.

When you TC is slipping, it is creating more heat. Heat is the number one enemy of transmissions.

You will find several tutorials out there to manually lock the TTC because many believe the computer unlocks it to soon. I have personally done this and love it.

Could you please site these references that state TTC lockup is bad for towing or low speed, this is the first I have ever heard of this.

More gear is never a bad thing if you plan to tow a lot. Becomes questionable on a multipurpose vehicle.

 

[RDF1]

You want the TC locked as much as possible.

When you TC is slipping, it is creating more heat. Heat is the number one enemy of transmissions.

You will find several tutorials out there to manually lock the TTC because many believe the computer unlocks it to soon. I have personally done this and love it.

Could you please site these references that state TTC lockup is bad for towing or low speed, this is the first I have ever heard of this.

I agree. I've mounted a switch on the dash before to manually lock my TC. Keeps the trans from heating up even with a large cooler and towing.

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[L31MaxExpress]

Lower gears and a reflash will definately help. Unloaded the gears will not make a huge difference in fuel economy. Depending on the tire size with a 454/4L80E, I used for towing, I would run 4.10 or 4.56 gears.

The TCC is controlled by multiple tables in the PCM. Most 4L80E calibrations lock the torque converter at WOT from 2nd gear and beyond but tend to keep it unlocked in 4th until you are rolling at a good speed. It is not unusual to feel the TCC unlocked in 4th, downshift to 3rd or 2nd and feel it lock right after the downshift.

 

[Tongan310]

If you have a black bear tune. Send it back and tell them your towing. My 4l80e is seeing a 18k toy hauler behind it. When empty its annoying (for me at least) when trying to drive normal and feel the damn thing lock up as soon as it shifts into OD (4th) its feels like 2 quick shifts. You feel the shift into 4th then bam lock up (almost feels like a slip) but when towing boy am I grateful for that..

 

[letitsnow]

Off topic, but my tow vehicle used to sit like that until I added a weight distribution hitch. You would like one, I assure you.

 

[L31MaxExpress]

Off topic, but my tow vehicle used to sit like that until I added a weight distribution hitch. You would like one, I assure you.

I see weight distributing bars under the trailer tongue

Perhaps they need to be adjusted more.

With weight distribution my TT only dropped the back end of the 1500 Express van about 1".

My trailer is 6,000 lbs, FWIW.