How We Fix GM Transmission Failure (6L80 & 6L90)

If you have a GM Truck or Van with a 6-speed transmission, built after 2006, these issues are likely to affect your truck. If you tow/haul frequently, or need to ensure as little down-time in your truck as possible, there are pre-emptive maintenance repairs that can be undertaken to prevent transmission failure.

This video focuses on what is happening, why, and touches on how National Transmission has developed a bulletproof fix for this issue.
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TIMESTAMPS

0:00 - Intro
0:50 - Transmission Tear-Down
1:01 - The Pan
1:33 - Reverse Drum
2:47 - Pump Assembly
3:16 - Torque Converter
5:20 - The Solution
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[rasputin]

I've got a 2016 1500, at 87k miles, and it just started slipping today. I am so heartsick. Can't afford this, worst possible time of year. Life goes on.

[jasonpantages]

Thank you for explaining the torque converter failure. I learned more from you in 5 min than the last year of watching YouTube videos about the 6l80 transmission, thank you again.

[falcorthewonderdog]

I'm a retired gm tech. I worked on hundreds of these 6L80 / 6L90 trans. Most common failure is the torque converter shelling out and pumping debris through the front pump. Never saw an issue with the 12345 R drum.

Another issue was with valve body issues.
Some could be cleaned and repaired. Others got a replacement valve body.

[SupremeVictoryStudios]

how is this not a recall? crazy thanks for the info.

[andrewtully]

I actually worked for a torque converter tier 1 supplier as a test engineer. Your component nomenclature of the Torque Converter is wrong. The base that attaches to the flex plate is the called the cover, and the opposite side is called the impeller/pump of the TC.

[kenbrake]

This is the best explanation of this I have seen. I live in northeast BC and I’ll be talking to you guys when it’s time to do my Transmission!

[SilverDollarSaloon]

The main failure of a transmission is overheating. Put a transmission fix on the trans oil by installing a thermostat update kit from superior solutions.

[Larry--]

Thank you, I have a 2015 Silverado 6L80 with all the vibration issues you speak about in your video, the thank you is for the detailed explanation you gave us and the actual torque converter split in half, great job & great video.

[StumpyVanLife]

2018 was not the last year for the 6L90, my 2019 Express 3500 has a 6L90. Wikipedia lists this transmission as 2010 to present in Express 2500 and 3500.

[monsfalco]

tell me about it dramatic failure is not the word for it. mine went so bad the entire driveline locked up almost like hitting the brakes, the dealership kept telling me it was fine its just the TCM needs a reflash lol yeah I said my transmission fluid smells burnt they said oh no its fine, I work at a shop I was well aware of what was going on, it was slipping hard shudders and super hard downshifts, this was just after purchasing the truck used from them a week and a half later, this transmission issue almost killed me I had a semi following just within a car length behind me, if I didn't react as fast as I did me and the truck would have been toast, safe to say exactly the issue you said in this video just more, since the vehicle was not covered on a warranty due to 241000 on the truck I only put 887 KM on that truck at that time, it cost $10, 000 CAD for a replacement not a rebuild that came out of the US due to none available at that time in Canada they covered half cost and footed me with the rest so far 15000Km on the new transmission and well its starting to do some odd things yet again, one is a odd ticking sound in the bellhousing something I have never heard any of these 2014 to 2018 trucks make ever I have seen a few come and go still unable to diagnose or even find information on that! she has 4 years and 100k warranty on the replacement so I am not worried just mad that this is so common love the truck otherwise.

[treybadd]

BS, the weld is not the problem man. The heat marks are from the manufacturing process and the fluid will keep surface temps pretty even. HERE IS THE REAL PROBLEM--The programming in the TCM / ECM commands torque converter apply in early gears and allows 20-40 rpm slippage. Actual slippage is much more. The torque converter never actually locks completely. It blows my mind why GM does this shit for smooth shifts and fuel mileage. It also blows my mind that people don't realize what's actually happening and why. HP tuners will fix this. Turn of DOD, and command less or no allowed slip. The torque converter is actually pretty good and has superior clutch material compared to standard lockup clutches.

[vadimnesen]

It's a conspiracy! Shops don't Wana replace just the torque converter they always claim the transmission got "destroyed". I can testify to this, my 6l80 shuddered for couple thousand miles than stopped moving completely, never slipped or shifted hard, me and my brother replaced the torque converter, changed the oil and filter 2 times now it drives like a dream. The oil pan and magnet had flakes and metal dust, about a cupful.

[DrMcnugget]

I have a 2015 Z71 Silverado 6-speed transmission, I get the Chevy Shake on the highway, I have had the trans checked and they said there was no metal shavings on the magnet, so then I had the tires and wheels done, then the U-Joints, then the CV axles done, then the bearings and bushings in the differential. Still shakes, i keep seeing the driveshaft or torque converter failure is what people say.

[danarcotta]

I had to have my transmission rebuilt on a 2015 GMC 1500 at 136, 000 miles. It still slips slightly, I removed just over a quart of fluid which improved that issue.. When I took it back, the shop told me that the fluid level was fine and that nothing was wrong. I also asked about that super solutions temperature gauge and the shop said that wouldn't make a difference. I live in Vegas and the temperature runs at an average of 189 degrees. I've got just over 7000 miles on it. It only slips slightly on slow speeds, generally in the morning. I've got a 2 year, 24, 000 mile warranty and I think it's probably going to fail again, further down the road. When I jump on it, it performs just fine.

[coupedayville]

2019 8L90e is the same problem, mine started under 80k miles, dealer can’t even get a replacement transmission and it’s been nearly 2 months!

[donlowe]

My 2015 Silverado has been parked for almost a year because of the faulty transmission. Waiting for the courts to order GM to fix.

[lpete]

Thanks this explains a lot about these 8 sp transmissions .Great video .

[donlowe]

The exhaust running under the transmission makes it hot also

[carlawooten]

I have a 8L90 transmission in my 2018 Sierra 1500 and would like to know if that torque converter would work in my truck and if so,
how can I get one. and also where are you located?

[t]

LOL if your transmission oil is black you know they have not serviced it as its supposed to be, they simply do the engine oil if that and run it down to the ground basically especially the trucks, they work them very hard and always never ever make sure if towing that the transmission has a real good external trans cooler and if its in hot humid weather, then get a trans cooler with a fan on it which is connected to a electronic switch to turn on if the trans fluid reaches more than say 85 degrees or better still make sure you have a control temp valve built in the trans cooler so it allows the oil to pass through at the spec temps and also a temp sensor as part of the cooler and pressure sensors as well, well worth it in the end, but heres the thing most owners do not care they simply run into the ground and then just upgrade and i feel sorry for those 2nd hand buyers who do not do their research on the real history of the truck they are buying?