Infamous 8 Speed Transmission Clunk - Dealer/GM Current Position on the Issue?

TRKLGND · April 26, 2019

On 3/21/2019 at 8:32 AM, benelli said:

Lol welcome to the club. All you guys forget about what the service advisors tell you. There all former mechanics that haven’t been under a hood I’m years. Dealerships bump them up to service advisors so they can upsale services most probably don’t need.

I worked at a Buick dealer and a Mercedes Dealer for 10 years. Not a single service adviser had ever been a mechanic. Not one. No mechanic would take the pay cut to be a service adviser.
Same thing at the Chevy dealer I currently use. None of them are old enough to have been "former" mechanics.

jqcitizen · April 30, 2019

Got an update from the Dealership today, They are going to replace the Transmission Valve body. Unfortunately it is on back order and they have no idea when it is going to come in. But it does look like it is coming from a different manufacturer, New Part Number. Hopefully this is a redesigned valve body.

Bikemobile · May 1, 2019

On 3/13/2019 at 3:50 PM, TXGREEK said:

Mine is just a SuperChips tune, set on performance along with disabling AFM and other preferences. Did notice acceleration difference too on my 6.2 after my CST lift and 34” Nitto Ridge Grapplers

Sent from above

Does the superchips tuner have a transmission setting?

TXGREEK · May 1, 2019

Does the superchips tuner have a transmission setting?

As of last year only for the six speed but they do have a newer model out now. You should go to their website and put in your vehicles information as well as call them with any additional questions you may have.

Sent from above

midwestdenaliguy · May 1, 2019

Welp, I made it 84k miles in my 2016 Sierra (6.2L, 8 speed) with zero transmission issues until I started to get a shutter on light acceleration and/or under load. It wasn't a horrible shutter, but definitely enough to get the attention of my wife and me. Dealer just replaced my torque converter and put in the updated fluid (paid courtesy of GM - $1900). Shutter is now gone, hopefully it stays that way. The dealership I use told me they have not had to replace any valve bodies yet on the 8 speeds that come in for the acceleration shutter - the torque converter replacement and new fluid has fixed them all so far. Interesting to see that is not the case for everyone on here. Coincidentally, the day I took it in an 8 speed Corvette was in for the same issue - only their's was described as a violent shake. Dealership says the vibration can vary greatly so they don't even chance it and replace TC and new fluid every time. They've also been successful in getting GM to cover the bill out of warranty.

LunkerHunter · May 2, 2019

Welp, I made it 84k miles in my 2016 Sierra (6.2L, 8 speed) with zero transmission issues until I started to get a shutter on light acceleration and/or under load. It wasn't a horrible shutter, but definitely enough to get the attention of my wife and me. Dealer just replaced my torque converter and put in the updated fluid (paid courtesy of GM - $1900). Shutter is now gone, hopefully it stays that way. The dealership I use told me they have not had to replace any valve bodies yet on the 8 speeds that come in for the acceleration shutter - the torque converter replacement and new fluid has fixed them all so far. Interesting to see that is not the case for everyone on here. Coincidentally, the day I took it in an 8 speed Corvette was in for the same issue - only their's was described as a violent shake. Dealership says the vibration can vary greatly so they don't even chance it and replace TC and new fluid every time. They've also been successful in getting GM to cover the bill out of warranty.

What Dealer???

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midwestdenaliguy · May 2, 2019

2 hours ago, LunkerHunter said:

What Dealer???

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Sapaugh Buick GMC in Herculaneum, MO (south of St Louis). They have been fantastic to work with anytime I've give in. Looks like a class action is moving forward with multiple states if your dealer doesn't have success with GM. Not sure how you get involved in the lawsuit though...

https://www.autoblog.com/2019/04/25/gm-transmission-class-action-lawsuit/

Tom beza · June 18, 2019

2017 Colorado .Having the 8 speed trans issue of jerk and shudder. Took into dealer yesterday. Mentioned the TSBs and the PIP to advisor, as well as I know there’s a lawsuit forming. This was at 7am. Advisor called me at 4pm and said should be good to pick up at 5pm. Finally ready at 545pm. They flushed it. I told them ok, see ya in a couple weeks when it starts up again. Lo and behold, it’s worse now. Dang near stalled in intersection, then a massive clunk and went on my way. Called service dept and they had all gone home early. I’m like really?

what is the ultimate final fix? Torque converter or new transmission? What is everyone’s final fix, if any?

had similar issue in an older S10 blazer. Same problems. 6 speed trans I believe. Gm denied any knowledge. Dealer finally bought me out of it after I brought in 250 printouts off a site like this. Dudes like, oh I guess there’s a problem. Lol

Beeler4034 · June 29, 2019

A friend of mine has a 2016 GMC Sierra 1500 Denali with the 8-Speed transmission and the 5.3L engine. He had the clunk between 1st and 2nd gears and he took it to a dealership several times where they finally replaced the Servo Motor. He said that he hasn't had any clunks after that and it has been a few months since it has been done. I have a 2017 GMC Sierra 1500 SLT with the 8-speed transmission and 5.3L engine and I have been experiencing the clunk. Mine seems to happen more when the truck has been sitting for a while and I start it up and immediately take off. After the truck warms up, it doesn't do it quite as much. I haven't had a chance to take my truck back in the dealership to ask about the clunk and the Servo Motors. I have about 35,300 miles on my truck already, so it is still under warranty.

Eneerge · July 20, 2019

Seems like I recall that a solid/steel driveshaft would fix the shuddering issue. In addition, based on hearsay, the plastic balls in the transmission make for a hard shift.

Unless I'm remembering wrong, my dealership installed a solid drive shaft and I haven't noticed the shudder anymore, but the shifting is still a little rough. A friend of mine mentioned something about a few plastic parts in the transmission that was responsible for hard shifting. He said the transmission should last longer, but may ultimately shift harder. I realize most of you are probably rolling their eyes right about now, but has anyone ever rebuilt the transmission that may be able to provide more insight?

My truck has had the torque converter replaced 3 times, ujoint, driveshaft, the roof started leaking at the shark fin, the door locks quit working ($700 out of warranty), the battery died, and an oil leak. Was not happy with my High Country purchase back in 2016. However, still driving it daily now after I was told the lemon law would not apply. Having a whining in the rear end now at low speeds. I've all but given up on GM and the dealership resolving anything, so I've been talking to locals.

Edited July 20, 2019 by Eneerge

Craigmkd · October 1, 2019

Wow- This is depressing. Wish I had found one of these forums a couple weeks ago. Just purchased 2019 Sierra 1500 5.3 and everything seemed fine for a few days. Then over the weekend slowing to a stop she came out of second very late (at least I think it was second) and clunk. I've driven pickups my whole life and this ain't right. I've read somewhere that swapping the fluid out helps but that seems to be a stretch. Bringing it in to dealer tomorrow wish me luck. I plan on towing with this truck and was wondering if this becomes worse while towing.

muhsfink07 · October 1, 2019

good luck! i did the fluid flush and it helped but still acts like a drunk sometimes...

mookdoc6 · October 1, 2019

6 hours ago, Craigmkd said:

Wow- This is depressing. Wish I had found one of these forums a couple weeks ago. Just purchased 2019 Sierra 1500 5.3 and everything seemed fine for a few days. Then over the weekend slowing to a stop she came out of second very late (at least I think it was second) and clunk. I've driven pickups my whole life and this ain't right. I've read somewhere that swapping the fluid out helps but that seems to be a stretch. Bringing it in to dealer tomorrow wish me luck. I plan on towing with this truck and was wondering if this becomes worse while towing.

Nope...the towing or weight makes it much less clunky!

Craigmkd · October 2, 2019

21 hours ago, mookdoc6 said:

Nope...the towing or weight makes it much less clunky!

Good to know Thanks. Haven't tried towing yet want to break it in more only has about 150 miles on it.

mnm99 · October 28, 2019

Just brought my 17 in for my brake booster pump failing. I asked them to check the tranny again, for the 5th time now. Every service or recall I bring it in and complain. They always come back with " Its normal, No problem, Couldn't find a problem" this time I drove with a tranny tech and he heard the 3-1 clunk. They said they want to drop the pan. If there are no shavings, they want to change the valve body. If there is they will go further. Of course there were no shavings and changed the valve body. This is the kicker.... When she told me it was ready she flat out said they are not doing another thing on this tranny unless it's a major problem. So if it still clunks , I guess it's normal...! She said if the tech drives it like 25 miles, it happens 2 times, it's not a problem. I said ok so how many times would it happen in 25000 miles? Because that's how much I have on the truck. That's a lot. I'm done with GMC....