My own 8 speed problems & resolution

wlezel · July 26, 2018

25 minutes ago, MD11G200 said:

Maybe I didn’t see were someone posted the price for the blackbear tune but it’s $599 and offers a low and high octane tune, that ain’t worth it for engine only in my opinion, I called after the post on here to confirm. My truck goes to the third dealership next week(one I purchased it from 3 hours away) a trade is in my future. Have had a chance to drive several 5.3 6 speed Chevrolet trucks and suburbans- transmissions smooth as glass, pisses my off because GM knows the 8 speeds ain’t right and refuses to fix there TCM

Hey @MD11G200, what year/engine truck do you have? I have a 2017 Sierra SLT with 6.2/8speed... only issue i've been struggling with is a rough/clunky 3-1 downshift. Other than that... tranny has been great. Dealership has tried the fast relearn... that didn't work. I'll be taking it back in again soon to have them look at it again.

MD11G200 · July 27, 2018

You and I have the same truck 6.2 Eight speed SLT one notch under Dinali- first time relearned the transmission at 5000 miles, transmission flush at 17,000 miles now to head back to the third Dealership who supposedly knows how to relearn it better, The one I bought it from,transmission is crazy does fine half the time horrible our other half the time under same Exact conditions but always seems to do right when I’m pulling something. Overall love the truck but this transmission will drive me to a trade probably. Have lots of friends who have the Toyota tundra and love it

Rme2513 · August 1, 2018

I talked to the dealer the other day about my torque converter acting up again and I was told that they have someone else building them now I'm guessing an outside company have any one heard of this or is that guy just trying to blow smoke up my ass

DCFisher · August 1, 2018

I have a 2106 Sierra SLT with the 5.3L and 8-speed transmission. My truck started to shudder when RPMs were between 1500 and 2000. It didn’t matter what gear my truck was in. You would see the RPMs jump up about 300 rpm when the shudder occurred. This started when I had around 28k miles on the truck. This was due to issues with the torque converter locking and unlocking. GM performed the triple flush to remove the contaminates that were preventing it from functioning correctly. The premature wear of the torque converter clutch plate is what contaminated my fluid and system. My truck drives much better now however I have only put around 4,000 Miles after the flush. I am concerned with the life of my TC and transmission. I plan to drive this truck for 200k plus miles. The shifting is not as clunky as it was when the system was contaminated. Has anyone had long term success with the flush only? Has the shudder come back after the triple flush? I told GM I wanted a new trans. I was told the flush should fix my problem. I don’t see how a flush adds the life back to my trans that was taken away by the premature wear on the clutch friction disc. I am thinking about trading for something else. I just don’t know what. I think I want a Duramax.

wlezel · August 1, 2018

3 hours ago, DCFisher said:

I have a 2106 Sierra SLT with the 5.3L and 8-speed transmission. My truck started to shudder when RPMs were between 1500 and 2000. It didn’t matter what gear my truck was in. You would see the RPMs jump up about 300 rpm when the shudder occurred. This started when I had around 28k miles on the truck. This was due to issues with the torque converter locking and unlocking. GM performed the triple flush to remove the contaminates that were preventing it from functioning correctly. The premature wear of the torque converter clutch plate is what contaminated my fluid and system. My truck drives much better now however I have only put around 4,000 Miles after the flush. I am concerned with the life of my TC and transmission. I plan to drive this truck for 200k plus miles. The shifting is not as clunky as it was when the system was contaminated. Has anyone had long term success with the flush only? Has the shudder come back after the triple flush? I told GM I wanted a new trans. I was told the flush should fix my problem. I don’t see how a flush adds the life back to my trans that was taken away by the premature wear on the clutch friction disc. I am thinking about trading for something else. I just don’t know what. I think I want a Duramax.

I too would like to know if anyone has had long term success with just a flush? My truck doesn't shudder but the 3-1 downshift is super clunky most of the time! I wonder if a flush alone would fix that problem.

thetruck454 · August 2, 2018

My 15 had the shudder and they did the tripple flush last summer. About 11,000 miles later it's just as bad as it was. I'm hoping a new torque converter will fix it.

Q007 · August 31, 2018

On 11/22/2016 at 4:11 AM, Dcollins25 said:

The stator support shaft update number is 16-na-014 it's not a normal number and it was applied to my 2015 aug build 6.2l . That said if you have the same symptoms in your 5.3l I would insist on having it changed. My truck now has 14000 miles and ito shifting is almost perfect.

@Dcollins25 Hey sorry for pulling this thread from so long ago. Just wanted to know if you ever had any more issues? I am looking at buying a 15 and make sure I don't get to into it. thanks.

MD11G200 · September 3, 2018

On 7/26/2018 at 7:24 AM, wlezel said:

Hey @MD11G200, what year/engine truck do you have? I have a 2017 Sierra SLT with 6.2/8speed... only issue i've been struggling with is a rough/clunky 3-1 downshift. Other than that... tranny has been great. Dealership has tried the fast relearn... that didn't work. I'll be taking it back in again soon to have them look at it again.

Just got back from 3rd dealership who this time stated they couldn't duplicate, they only drove it 3 miles. I am hoping and praying someone creates a tune for this bc it looks no end in sight for my occasional clunk that's so hard its bound to brake something eventually. GM YOU F'ing SSSUUUUCCCKKK!!!!!!!!!!!!!!

MD11G200 · September 3, 2018

On 7/20/2018 at 11:08 AM, huntr1117 said:

I pretty much had the same issues with my 17 6.2. I took it into the dealer a few times and they updated the ecm/tcm, and did the fast relearn. Clunk came back about a week later each time. Brought it in again and they did the same thing but also went ahead and flushed the trans. It made a huge difference. Now I'm not positive that the flush is what made it better, but that's the only difference. It's not 100 % fixed. I will still get a random hard downshift but rare now. I figure that once my warranty is up I'll get Blackbear to tune it, but for now I'm fine with it. I'm at 26k miles now so it wont be long. I'd definitely have the dealer do the trans flush/filter.

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Is your transmission issue resolved? I'm still searching for answers

huntr1117 · September 3, 2018

Is your transmission issue resolved? I'm still searching for answers

I wouldn't say its totally resolved. It's way better than it has ever been. Still the occasional clunk but its rare. I'm guessing a tune is the only way to completely fix it. Strange thing is that when I reinstalled my CAI the random shifting came back. I think its because when I brought it in last time and they did the trans relearn procedure it was with the stock intake. It also may have to be addressed with a tune. I need to bring the truck back in because of a noise in the steering column. When I do I'll see if they'll do the trans relearn again with the aftermarket CAI installed.

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B R A D · September 4, 2018

I wouldn't say its totally resolved. It's way better than it has ever been. Still the occasional clunk but its rare. I'm guessing a tune is the only way to completely fix it. Strange thing is that when I reinstalled my CAI the random shifting came back. I think its because when I brought it in last time and they did the trans relearn procedure it was with the stock intake. It also may have to be addressed with a tune. I need to bring the truck back in because of a noise in the steering column. When I do I'll see if they'll do the trans relearn again with the aftermarket CAI installed.

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Good luck getting that noise fixed. They changed my upper and lower steering shaft after greasing didn't work.But if you do write back and let us know what it was.

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YukonXL04 · September 4, 2018

18 sierra 6.2 8spd, no issues at all here. Wondering if anything was changed for the better on the 18s...

benelli · September 6, 2018

On 3/12/2018 at 3:07 AM, benelli said:

Look at earlier posts. Gm hides behind there known issues. They make customers come in they claim to do a relearn on the trans which is not the problem and is a waste of time. customer comes in they say they tried something. customer leaves same thing. unless your retired and have nothing to do all day you would have to take your truck in to them once a week and they still wont fix anything. why don`t they just admit to customers that they screwed up on this transmission. when i told my dealership i was trading this in there response was oh maybe you can trade it in for our 2019 it has a 10 speed. LOL. I told them are you f***ing crazy. you cant even get this one right.

Ok here is an update to this harsh shift from rolling stop or 1-2 shifts. I finally spoke with a master Tech at one of my Dealerships. Young service manager very nice guy. Was able to speak with him for a hour. Mechanic To Mechanic. He informed me that they have hundreds of same complaints about the 8 speed transmissions. and that`s only at there dealership. He said its a word wide problem. The transmissions are fine it is definately a software program issue. He advised forget about the relearns and the trans flushing and the all that crap that these dealers do to try and fix the issue. IT WONT WORK. wasting your time and there going to create more problems with tearing it apart trying to change this and that. no Torque converters or anything will fix the issue other than a new software update to address the issue. I asked how about an aftermarket tune from superchips or bear. He said absolutely he would do that on his for this issue. i said well what about the warranty if something goes wrong with the Transmission. Also advised that and if you get my point if there is a major breakdown of the drive train weather it be motor or transmission. Gm Canada will ask for the computer history of ONLY the engine Not The Transmission software. so even if you have a tune in there and dont remove it before you bring it in. He says gm never asks for the transmission software history. On Another note the new 2019s are rolling out soon so they have addressed the issue on these transmissions weather they be 8 speed or 10 speed type. He seems to think they will adapt the new software program to these troublesome transmissions and it will resolve the hard shift issues. ohh he also said sierra 6.2 with the 8 speed has fewer complaints about the shifting presumably because of the larger engine and therefor a different software program.

Edited September 7, 2018 by benelli

benelli · September 6, 2018

On 9/3/2018 at 3:50 PM, MD11G200 said:

Is your transmission issue resolved? I'm still searching for answers

Report post

Posted 2 hours ago

On 3/12/2018 at 3:07 AM, benelli said:

Look at earlier posts. Gm hides behind there known issues. They make customers come in they claim to do a relearn on the trans which is not the problem and is a waste of time. customer comes in they say they tried something. customer leaves same thing. unless your retired and have nothing to do all day you would have to take your truck in to them once a week and they still wont fix anything. why don`t they just admit to customers that they screwed up on this transmission. when i told my dealership i was trading this in there response was oh maybe you can trade it in for our 2019 it has a 10 speed. LOL. I told them are you f***ing crazy. you cant even get this one right.

Ok here is an update to this harsh shift from rolling stop or 1-2 shifts. I finally spoke with a master Tech at one of my Dealerships. Young service manager very nice guy. Was able to speak with him for a hour. Mechanic To Mechanic. He informed me that they have hundreds of same complaints about the 8 speed transmissions. and that`s only at there dealership. He said its a world wide problem. The transmissions are fine it is definately a software program issue. He advised forget about the relearns and the trans flushing and the all that crap that these dealers do to try and fix the issue. IT WONT WORK. wasting your time and there going to create more problems with tearing it apart trying to change this and that. no Torque converters or anything will fix the issue other than a new software update to address the issue. I asked how about an aftermarket tune from superchips or bear. He said absolutely he would do that on his for this issue. i said well what about the warranty if something goes wrong with the Transmission. Also advised that and if you get my point if there is a major breakdown of the drive train weather it be motor or transmission. Gm Canada will ask for the computer history of ONLY the engine Not The Transmission software. so even if you have a tune in there and dont remove it before you bring it in. He says gm never asks for the transmission software history. On Another note the new 2019s are rolling out soon so they have addressed the issue on these transmissions weather they be 8 speed or 10 speed type. He seems to think they will adapt the new software program to these troublesome transmissions and it will resolve the hard shift issues.

Edited September 7, 2018 by benelli

MD11G200 · September 7, 2018

2017 GMC 6.2 8 speed-So far my clunky transmission problems are much better after I installed a Range AFM disabler. Truck drives much better and shifts much soother(2 weeks now) I agree it’s been software all along that’s why no one could consistory produce the problem when at the dealership. No Transmission tune at this time as indicated by this thread. Right now, AFM disabler did the tune for me, hope it lasts.