6L80E discussion

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6L80E Torque Converter failures on K2XX platform (2014-2019 GM Truck) have skyrocketed & will eclipse Converter failure rates in GMT900 platform (2007-2013 GM Truck) by a huge margin.

I'd like to know how many K2XX truck owners we have here with over 175,000 miles on their original 6L80E?

I have one customer with well over 200,000 on his 2015 Silverado.....But I installed a Billet Front Twin Disc Converter preemptively. Interestingly enough I had the original converter cut open & no discernable wear was found. He is a VERY aggressive driver that likely uses 3/4 to full throttle more than I've ever seen! The TCM ramps up TCC apply pressure almost linear with Calculated Applied Torque.

I believe GM was chasing Fuel Economy by providing barely adequate TCC apply pressure & was chasing reduced NVH with the constant TCC slip in V4 mode that's more aggressive than was calibrated in the AFM GMT900 platform.

Been talking with my Converter builder about adapting a TMBX 300mm 4L60E Converter to fit in place of a JMBX 300mm 6L80E Converter, There are just enough differences where it's not financially feasible to train his staff & convince other shops to spend $70 more per converter when a rebuilt JMBX will make it through warranty.

Sonnax has a Billet Front Twin Disc kit....But it's NOT cheap, Especially when added to a already very expensive job where the Pump, Stator & Coolers need to be replaced at bare minimum beyond all the Soft Parts that normally get replaced during a rebuild.

This is the 5th K2XX truck I've had come in the last 30 days with a failed converter & I have 3 more waiting to be diagnosed. I don't even test drive them anymore......I pull the pan FIRST, No sense in pumping anymore shrapnel through the unit. Then I have another 5-6 calls per month from folks that can't wait on me to get to their truck, Which is fine with me as I don't deal well with antsy folks seeking instant gratification.

In a perfect world, Owners would have a Billet Front Converter & a Custom Tune done before/at 100,000 miles OR any 6L80E that's free of shrapnel in the pan.

If you feel any sensation that feels like you're running over a Rumble Strip.....That's likely your TCC dying.

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I wonder how FCA/Stellantis has their MDS/V4 mode programmed after reading your rumble strip example. Sometimes my truck gets a bit “rumbly” when in MDS before kicking out, there is definitely a little flare when it kicks in and out of it, but I don’t recall reading really any torque converter failures on the NAG1, 545RFE/65RFE nor the ZF 8 speeds.
 
I personally know no one with 175,000 miles on the 2014-2018 6-speeds that have made it that far, but I know two that are in the 120,000 range. Both drive their vehicles pretty hard, tow/haul stuff for work. I don’t think they spend a ton of time in V4 mode.

As I’m sure you know, if you to the forums the 6-speeds toque converters are failing at a high rate. There are dealership techs that chime in and talk about how they replace them every single day at the dealer. All usually before 120,000 miles. Some as low as 40,000 miles.

But the thing about being proactive and tuning it out and installing that converter with that billet unit, it’s expensive, what does that whole procedure cost? $2,000? And for some people they don’t want to tune out the V4 because they’re averaging 24 plus mpg. But I think it’s great that it’s possibly a solution - because to replace one of these trannys every 100,000 miles is ridiculous.

I‘ve run into people on this site that deny it’s an issue at all and...”how can I determine it’s a big issue when they sell 500,000 of these things a year and of course the forums and dealer techs are going to see a lot of them, but mine is just fine”. Type stuff.

Traded mine in with 50k on it, well maintained and absolutely babied. I think that was part of my problem, I babied it, drove it too easy and it constantly was shifting...up and down, in and out of torque converter engagement because I was always in and out if V4. But I started experiencing that shudder at around 35,000 miles.
 
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I have seen 6L90E goes that distance, but no 6L80E in the 14 and up truck. The 80E in my Caprice is nice.
 
I wonder how FCA/Stellantis has their MDS/V4 mode programmed after reading your rumble strip example. Sometimes my truck gets a bit “rumbly” when in MDS before kicking out, there is definitely a little flare when it kicks in and out of it, but I don’t recall reading really any torque converter failures on the NAG1, 545RFE/65RFE nor the ZF 8 speeds.

Like I stated......Really wanted my Converter guy to build me a Hybrid 4L60E converter for this unit because failures of the TC Clutch was/is very few & far between even when used in constant slip AFM applications.

Then I can log TCC Slip RPM vs TCC Regulator Solenoid Duty Cycle to get an idea how the 2 TCC set-up's react to the same pressures. For all I know the 4L60E TMBX clutch will shudder like crazy when subjected to a 6L80E JMBX clutch control scheme or be an overall poor fit for the application.

I have hours & hours of Data Logs of stock (Known Good) K2XX TCC behavior, And have built some really good Custom Calibrations that center around turning off the AFM, AFM TCC Slip, And pretty aggressive TCC Pressure vs TCC Slip Error apply pressure Ramps.

My concern is......Am I causing the Stamped Front Cover to flex by adding to much apply pressure? Let's take a 2006 Chevy Silverado SS with a 345hp LQ9/4L65E & stock TMBX converter.....Assuming there is no TCC Regulator Valve Bore wear. The TCC will hold a +/- 2 RPM slip at anything over 50% PWM duty cycle.

A 6L80E JMBX just doesn't seem to hold anywhere near that well.


Interesting note.....The JMBX is manufactured by Sachs ZF where the TMBX was manufactured in-house by Hydramatic, Wonder if there was a miscommunication on the specs between GM & ZF? Or GM was trying to save a nickel & specified a barely adequate TCC for the application?

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Interesting note.....The JMBX is manufactured by Sachs ZF where the TMBX was manufactured in-house by Hydramatic, Wonder if there was a miscommunication on the specs between GM & ZF? Or GM was trying to save a nickel & specified a barely adequate TCC for the application?

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ZF was probably their supplier because they rolled out their Lepelletier transmission 5 years before and had some expertise. is the 6L50E also using a ZF TC unit?

the 6L family even shared the main harness connector with the 6HP
 
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They share the Lepelletier system of a Ravigneaux gearset with a Overdrive/Underdrive Simpson gearset on the Input....Which why they don't have a Direct Drive.

But the architecture is quite different between a 6HP/6R80 & a Hydramatic 6LxxE.
 
I personally know no one with 175,000 miles on the 2014-2018 6-speeds that have made it that far, but I know two that are in the 120,000 range. Both drive their vehicles pretty hard, tow/haul stuff for work. I don’t think they spend a ton of time in V4 mode.

As I’m sure you know, if you to the forums the 6-speeds toque converters are failing at a high rate. There are dealership techs that chime in and talk about how they replace them every single day at the dealer. All usually before 120,000 miles. Some as low as 40,000 miles.

But the thing about being proactive and tuning it out and installing that converter with that billet unit, it’s expensive, what does that whole procedure cost? $2,000? And for some people they don’t want to tune out the V4 because they’re averaging 24 plus mpg. But I think it’s great that it’s possibly a solution - because to replace one of these trannys every 100,000 miles is ridiculous.

I‘ve run into people on this site that deny it’s an issue at all and...”how can I determine it’s a big issue when they sell 500,000 of these things a year and of course the forums and dealer techs are going to see a lot of them, but mine is just fine”. Type stuff.

Traded mine in with 50k on it, well maintained and absolutely babied. I think that was part of my problem, I babied it, drove it too easy and it constantly was shifting...up and down, in and out of torque converter engagement because I was always in and out if V4. But I started experiencing that shudder at around 35,000 miles.
I consider this a mixed (half-true) statement-they do sell a massive number-and we must be on different forums, the issue does come up-but no to the degree you are experiencing or implying. But you are right-if you cruise at no more than 70mph-you can get 25mpg on the highway all day long.

I have owned three with these transmission with zero issues.
 
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I consider this a mixed (half-true) statement-they do sell a massive number-and we must be on different forums, the issue does come up-but no to the degree you are experiencing or implying. But you are right-if you cruise at no more than 70mph-you can get 25mpg on the highway all day long.

I have owned three with these transmission with zero issues.
I go to this one, it’s (I think the most popular Chevy truck forum on the internet).


In the first two pages there are 10 transmission problem/trouble threads. Four on the first, six on the second.
 
I go to this one, it’s (I think the most popular Chevy truck forum on the internet).


In the first two pages there are 10 transmission problem/trouble threads. Four on the first, six on the second.
You must not have Facebook. A couple of 2014 to 2019 forums on there are twice membership of that forum.
 
I consider this a mixed (half-true) statement-they do sell a massive number-and we must be on different forums, the issue does come up-but no to the degree you are experiencing or implying. But you are right-if you cruise at no more than 70mph-you can get 25mpg on the highway all day long.

I have owned three with these transmission with zero issues.

Pretty sure we've had this discussion before, You trade your trucks in before 100K IIRC?? I think the failure rate before 100K is probably pretty low. The bulk of the failures I see are in the 150K range.
 
I go to this one, it’s (I think the most popular Chevy truck forum on the internet).


In the first two pages there are 10 transmission problem/trouble threads. Four on the first, six on the second
 
If you look at some of those threads referenced in the truck forums some of them are not issues at all-but characteristics of said power train. Again-between the SIlverado and Sierra there are well over 40,000 units sold a month. Some reference a lazy/delayed shift or clunk in the powertrain. This is not indicative of potential failure. I know I have owned three.
 
When I had two 6L80E units (truck and SUV 2018/2017) … the AFM behavior difference was very noticeable
The truck was seldom in 4C … the SUV very often. Truck was traded low mileage (28k) but the powertrain was one of the most pleasant I ever owned (mid life mistake thinking I’d like a regular cab 4WD again) …

With just a simple tire change … slightly wider/taller - not “fuel saver” I had … the Tahoe is now chasing its tail 4C/8C at highway speeds … but I ask how many drivers would actually notice that? (made same switch on truck-no reaction)
Not good on the 6L80E nor the valve train … Ordered a Range plug in and will install that soon …
 
If you look at some of those threads referenced in the truck forums some of them are not issues at all-but characteristics of said power train. Again-between the SIlverado and Sierra there are well over 40,000 units sold a month. Some reference a lazy/delayed shift or clunk in the powertrain. This is not indicative of potential failure. I know I have owned three.
Some? Ok. That was done without even doing a search. Here’s a search. But I stopped after five minutes because I needed to get on with my day.😀






Some of these guys^^are on their third torque converter. 🤣 Nothing to see here.



I understand they sell a lot of these trucks, but it is a problem regardless. It’s too frequent and a transmission should last more than 120,000 miles. Mine barely made it to 50,000 before I traded it in because the converter in my 2018 6-speed couldn’t handle driving up hills on the HIGHWAY anymore. Not towing anything, not hauling a trailer, just easy up and down the highway commuting next to Honda Accords and Nissan Rogues. Easy stuff. Not a construction site pulling equipment and idling all day, going from job to job. Just driving to work doing 68 mph on an easy 80 mile round trip commute. Maintained meticulously be an ASE master Tech (myself).
 
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