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GM 8-Speed Transmission Lawsuit Heats Up - Does Yours Shudder?

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Carcomplaints gm trans.png

John Goreham
Contributing Writer, GM-Trucks.com
4-25-2019

Back in December, GM-Trucks.com member Jammin87SS posted a note here about a class-action suit related to GM 8-speed automatic transmissions. This transmission was used widely by GM, including in the Sierra, Silverado, Colorado, and Canyon pickup trucks. Owners have been complaining of shuddering and hesitation. Owner of a Silverado, Ed T., wrote a typical description for CarComplaints. He says, "Ever since I bought this truck new there has always been a shifting problem. This problem occurs whenever I slow down to a fairly low speed and then accelerate. When I accelerate there is a hesitation for a second or 2. This is very annoying and could potentially be dangerous. I have contacted my dealer and he just says "that's the way they shift, no fix"??? Dealer also stated that the transmissions have a learning chip and shifts the way a person normally drives - that's total BS. I have had my truck for over 2 years and it still shifts poorly. Besides the above I love my truck very much, GM just has to fix this problem..."

 

GM trans 16 carcomplaints.png

 

GM knows there is a problem. It has issued both notices to its dealer's technicians and also TSBs. However, it has yet to find a solution that works.

2016-Cadillac-CT6-Powertrain-AutoTrans-8l45 8 speed.jpg

There is a class action suit that you can learn more about here. Our questions for our members are; 1) Have you experienced any issues with your 8-speed, and 2) was the dealer able to fix it? Let us know in the comments below.  

 

 

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Looks like GM will be putting MQE's in place of the M5U's?  I would expect nothing less as this has been a major problem for them for years.  Anybody who has ever hit the gas in a pinch and their truck just sits there knows what I am talking about!  Scary and dangerous!

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Exxon Mobil just changed the formulation for Dexron HP a few months ago. GM released a new TSB 18-NA--355 that instructs them to flush and fill with it. How do we know that the new Dexron HP didn't fix the 8-speed?

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I have had and still do have the issues with the transmission as described. I have not taken it to the dealer to be looked at, as it wasn't 'bad' enough for me to want to take it in since the last problem I took for them to look at, they crashed my truck (this was at 1 month of ownership too!). It's more noticeable when it's cold than when the vehicle is warm. It does feel like it's gotten better now, but I think it's probably because I'm must more used to it. 

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IMHO it is the AFM system that makes most of the 6 or even 8 speed 2014 and up GM trucks shift like crap.

I have proven this myself by running my 6 speed around in M5 or using E85

Overall I like my 6 speed and it shifts smooth and behaves like it should but every now and then it is confused and a bit clunky.

Most of this bad behavior occurs in correlation with switching back and forth from V4 to V8

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Posted (edited)
1 hour ago, 3tspapat said:

I have had and still do have the issues with the transmission as described. I have not taken it to the dealer to be looked at, as it wasn't 'bad' enough for me to want to take it in since the last problem I took for them to look at, they crashed my truck (this was at 1 month of ownership too!). It's more noticeable when it's cold than when the vehicle is warm. It does feel like it's gotten better now, but I think it's probably because I'm must more used to it. 

So you haven't been in for the new TSB?

https://gm-techlink.com/?p=11127

 

TCC Shudder and New Mobil 1 Fluid Exchange

January 31, 2019

 

"A new transmission fluid exchange procedure and a new formula of Mobil 1 Synthetic LV ATF HP transmission fluid have been released to address torque converter clutch (TCC) shudder conditions on 8L45 and 8L90 8-speed automatic transmissions (RPOs M5N, M5T, M5U, M5X) in some 2015-2017 Escalade, Yukon; 2015-2018 Silverado, Sierra; 2015-2019 Corvette; 2016-2018 CT6; 2016-2019 ATS, CTS, Camaro; and 2017-2019 Colorado and Canyon models."

 

"The TCC shudder condition is related to moisture content in the transmission fluid. The current fluid tends to be hydroscopic, or absorbs moisture, which increases the chance of TCC shudder. There are three different fluid exchange procedures to follow, depending on vehicle application, so that an acceptable concentration of the new HP fluid is achieved in the transmission."

 

"The new Mobil 1 Synthetic LV ATF HP transmission fluid is now available to U.S. dealerships through your local GM Oil Distributor. The new Mobil 1 Synthetic LV ATF HP transmission fluid is available in quart bottles (GM Part Number 19417577) and, for a limited time, in 55-gallon drums (GM Part Number 19417904) (Fig. 12) in most locations. Drum production ended in January 2019. The GM part numbers are not on the product. The Mobil 1 Synthetic LV ATF HP fluid and the required tool kit will be available to all Canadian dealerships by the end of March 2019. GM Part Numbers for 0.946 liter bottles will be provided at that time."

Edited by HondaHawkGT

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I haven't been in for anything since December. The shudder in reverse used to be very noticeable when i first got the truck. Now it's not noticeable. I wonder if they had done the TSB back in December. If they haven't, I was just going to hold out until later and then swap the pan and fluid myself. 

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I took mine 2015 in for delayed reverse engagement, TSB said they would be changing a stator shaft they had since redesigned. Dropped the truck off, when I came to pick it up they had told me they had to swap transmissions for a Re-man unit. This really pisses me off as there was 30,000km on the truck at the time. I don't feel I should have someone's previously ****ed up transmission in my truck that is essentially new. Mind you, it shifts beautifully now, no complains at all (for now) besides refurbished 8L90e making their way into new pickups. Reman parts are for 8 year old truck that you don't have a warranty on anymore, not new ones. I don't feel we should have to suffer because GM put a unit on the market that was not ready for sale. Surely in the 2 million + test miles they would have encountered these issues and corrected them, rather than pass the problems to devoted customers. GM's goodwill took a big hit with the K2 in my books.

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YES!  Sitting in my garage, when I drop it into reverse with my foot on the brake pedal, the thing feels like when you go from forward to reverse without fully stopping, it jerks into reverse.

 

I have also had a few hard shifts from first to second at very low speeds and low throttle input... basically there is no real reason for it to jerk and lurch like it does.  

 

Mine is not bad enough for me to address it, but I do wonder what that reverse jerking will do to my differential and drive shaft over time.

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My 2019 RST did something odd today. I’ve been noticing a few hard 1-2 shifts when it’s cold, for sure. But it was very warmed up today - had been driving around a good 30 min - and I did a 3-point reverse at a very slow speed. When I shifted from R back to D, I went about 2-3 feet and felt a hard jerk. 

 

I’ve had the truck about a month and it has around 1100 on it now. First time it has done this. 

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On 4/26/2019 at 9:17 AM, L86 All Terrain said:

I took mine 2015 in for delayed reverse engagement, TSB said they would be changing a stator shaft they had since redesigned. Dropped the truck off, when I came to pick it up they had told me they had to swap transmissions for a Re-man unit. This really pisses me off as there was 30,000km on the truck at the time. I don't feel I should have someone's previously ****ed up transmission in my truck that is essentially new. Mind you, it shifts beautifully now, no complains at all (for now) besides refurbished 8L90e making their way into new pickups. Reman parts are for 8 year old truck that you don't have a warranty on anymore, not new ones. I don't feel we should have to suffer because GM put a unit on the market that was not ready for sale. Surely in the 2 million + test miles they would have encountered these issues and corrected them, rather than pass the problems to devoted customers. GM's goodwill took a big hit with the K2 in my books.

 

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On 2019-04-25 at 10:13 AM, Gorehamj said:

Carcomplaints gm trans.png

John Goreham
Contributing Writer, GM-Trucks.com
4-25-2019

Back in December, GM-Trucks.com member Jammin87SS posted a note here about a class-action suit related to GM 8-speed automatic transmissions. This transmission was used widely by GM, including in the Sierra, Silverado, Colorado, and Canyon pickup trucks. Owners have been complaining of shuddering and hesitation. Owner of a Silverado, Ed T., wrote a typical description for CarComplaints. He says, "Ever since I bought this truck new there has always been a shifting problem. This problem occurs whenever I slow down to a fairly low speed and then accelerate. When I accelerate there is a hesitation for a second or 2. This is very annoying and could potentially be dangerous. I have contacted my dealer and he just says "that's the way they shift, no fix"??? Dealer also stated that the transmissions have a learning chip and shifts the way a person normally drives - that's total BS. I have had my truck for over 2 years and it still shifts poorly. Besides the above I love my truck very much, GM just has to fix this problem..."

 

GM trans 16 carcomplaints.png

 

GM knows there is a problem. It has issued both notices to its dealer's technicians and also TSBs. However, it has yet to find a solution that works.

2016-Cadillac-CT6-Powertrain-AutoTrans-8l45 8 speed.jpg

There is a class action suit that you can learn more about here. Our questions for our members are; 1) Have you experienced any issues with your 8-speed, and 2) was the dealer able to fix it? Let us know in the comments below.  

 

 

I am told that the clutch piston not being able to drain fast enough is the problem. 

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On 2019-04-25 at 10:53 AM, mookdoc6 said:

Looks like GM will be putting MQE's in place of the M5U's?  I would expect nothing less as this has been a major problem for them for years.  Anybody who has ever hit the gas in a pinch and their truck just sits there knows what I am talking about!  Scary and dangerous!

YESSSSSS! This is exactly what mine does!!! Almost killed me twice.

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I am curious as to why they don't just swap out the 8 speed transmissions that are causing problems with the new 8 speeds. Seems like it would be cheaper for them in the long run. My 8 speed in my 16 was a joke and I traded it at 7500 miles but wasn't sure what was wrong until reading here. Dumb me I bought another 6.2 with 8 speed. I haven't had any trouble with it but I only have 4500 miles or so. My wife's 17 Yukon Denali has the 8 speed also and 20,000 miles but all seems ok.


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36 minutes ago, AgDoctor said:

I am curious as to why they don't just swap out the 8 speed transmissions that are causing problems with the new 8 speeds. Seems like it would be cheaper for them in the long run. My 8 speed in my 16 was a joke and I traded it at 7500 miles but wasn't sure what was wrong until reading here. Dumb me I bought another 6.2 with 8 speed. I haven't had any trouble with it but I only have 4500 miles or so. My wife's 17 Yukon Denali has the 8 speed also and 20,000 miles but all seems ok.


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Because some of us have the new 8 speeds, and they have the same problems. Lol! 🤔🙈

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