My own 8 speed problems & resolution

Jimmyc! · March 20, 2016

About 250 miles ago I had the "Re-learn" performed at my dealer. Sadly the issue is still happening. I'll be making another appointment to head to step two of this process. What it is I don't know.

JacobC1983 · March 20, 2016

Interesting thread.

2015 GMC Sierra SLT with 6.2L and 8 speed.

Have had my truck in for a re learn twice and a new torque converter. None seem to fix the issues. I have random clunking and hard shifts. Then the next time I drive it, it will be smooth.

Then the following morning it will be a clunky, rough shifting pile of garbage.

was thinking about trading the truck for something else... It appears there is no end in sight.

Edited March 20, 2016 by JacobC1983

rice33 · March 22, 2016

Thanks for sharing you experience.

I just bought a brand new 2016 Sierra Denali 1500 5.3 with an 8 speed transmission.

It currently has just under 1500 miles and there is no clunk. However, the transmission is acting funny when I accelerate lightly from a stop. It shakes and lacks power. Feels like it shifts from 1st to 3rd or 4th gears under light acceleration. Not a very reassuring experience. Then I look at the tach, and I am only at 1700 RPM - As I said, light acceleration.

Was thinking to bring this up to a dealer, but I KNOW the answer - Completely Normal or Give It More Gas. But what if I don't want to give it more gas?

We will see how it behaves at 5K.

JacobC1983 · March 22, 2016

My truck did the same thing before they installed the torque converter... The dealer called it a "shudder" when shifting.

brendan4862 · March 23, 2016

Another update:

I just dropped the truck off at the dealer this evening. I just hit 10000 miles. The tech wanted to hear it. I drove, and I got it clunking quite a bit. He told me the way my transmission was clunking was NOT normal. He also said they have had a lot of concerns with 8 speeds. He said most of the 8 speeds have slight clunking that is due to tolerances/backlash which is understandable. He also mentioned the torque converters have been known to 'shred' themselves and create a lot of debris. Either way the 8 speed is not doing so hot. GM is working on it a permanent fix, but no absolute fix yet.

I can't say enough good things about my dealer though. They told me if it can't be fixed, or it comes back from GM I 'have to live with the clunk' that they will help with either trade assistance or buy it back. I really hope they can figure out a fix. It's a damn nice truck.

To those of you having any kind of doubt, bring it in to the dealer and at least have them document it. I live an hour away from the dealer, so I know how much of a pain it is going to the dealer. These trucks cost too much to settle for these transmission issues.

JacobC1983 · March 23, 2016

Are people with 2016 models and the 8 speed transmission having the same issues?

brendan4862 · March 24, 2016

Are people with 2016 models and the 8 speed transmission having the same issues?

Not sure if the 2016 8 Speeds are quite as bad. The tech told me the transmissions currently being put into the trucks have an updated torque converter. That was one problem. My tech was very friendly and did say they have had a 'slew' of problems with the 8 Speed.

HERE IS ANOTHER UPDATE:

I picked the truck up last night after a 24hr turn around from my dealership. They took the truck for a four hour drive as they called it and did the relearn adapt while driving around. They had one guy drive, and another with the computer monitoring the transmission. Check out my service description:

The drive home seemed to be much smoother. I will let you all know how it goes. I have spoken with the service manager, my sales man, and the manager of my dealer and if this doesn't meet my satisfaction they have agreed to buy it back. I have been ultra patient with this whole thing, and they have been more than willing to help me this. At least there are some dealers out there that care about the customer. Believe me, I have had my fair share of different dealerships treat you like crap.

I hope this fixes it because I do enjoy driving this truck around.

brendan4862 · April 12, 2016

Alright everybody. Here is the verdict.

I have an appointment tomorrow morning to bring the truck back to my dealer. The 'reprogram' did not help at all. They told me to drive 500 miles after the program to help it 'learn' further. I drove it 1000 and it still does the same clunks. All low speed clunks. I know exactly when it will clunk now, so riding with my dealer should show them my issues.

At this point I am planning on getting rid of the truck. I tried multiple times to have GM fix this damn 8 speed/clunk fiasco and they have failed so far. Really disappointing as this was my first new truck.

I know I am not the only one with this issue, and I know not every truck built has this issue. I wish all of you luck with your trucks moving forward.

JacobC1983 · April 13, 2016

Let us know how it goes. I have the exact same issue with my 6.2L and 8 speed 2015 GMC Sierra. I get a driveline clunk at least once a week that sounds like the rear end wants to fall out.... and other times the clunks are smaller. Sometimes it shifts perfectly.

It is a nightmare trying to get my dealer to understand exactly what it is doing. I wish GM would buy it back and I could get a different truck. I don't want to lose the depreciation on this one.

Edited April 13, 2016 by JacobC1983

Tony Bianco · April 13, 2016

So much for my trading for an 8 speed this year ..... guess I'll stick with the 6 speed.

Rkaroll953 · April 14, 2016

Did the trans clunk and get all confused when coasting to acceleration in Tow Haul too?? my 6 speed will get confused but wont clunk and all that. Tow haul it drives like it should, hold gears longer, engine brake better etc.

brendan4862 · April 15, 2016

Did the trans clunk and get all confused when coasting to acceleration in Tow Haul too?? my 6 speed will get confused but wont clunk and all that. Tow haul it drives like it should, hold gears longer, engine brake better etc.

Tow haul was much better. I agree. But I did not want to be driving around in Tow/Haul mode all the time to help with the trucks shifting. It's ridiculous to have a brand new truck and every time you get in say "oh yeah, tow/haul so it shifts properly"

brendan4862 · April 15, 2016

Service update:

I took the truck into the dealer Wednesday at 9am and went on a test drive with one of the transmission techs. It clunked as soon as we left the parking lot, and it shook the whole truck. The tech said 'turn around, its clear there is something wrong' We got back to the shop and I took off with a loaner while I ran some errands. The service manager called three hours later and said there were no updates available, and they have tried everything to take care of the clunking per GM. He then told me that if I drive the truck in manual mode at gear 6 or 5 that would help a lot with the clunking. And it's what they're telling people to do. I was not happy at this statement and told him why would I do that and completely negate the idea of an 8 speed. If that's the case they should have left a six speed in there!

Another thing the service manager told me: We have replaced your transmission, made sure it had up to date software, and made sure the torque converter was an updated model. GM has advised us that if those steps have been taken, there is no other option but to live with the problem. GM has said they will address all the issues with the 8 speed starting with the 2017 model year trucks. But they are not putting more effort than the described fixes above into the 2015-2016 8 speeds.

This is what my service manager told me. Needless to say I am both upset and sad with GM.

Buy Back update:

I asked them to buy the truck back straight up. No trade, just take it and give me a check. I met with the service manager and my sales rep and I told them I want GM to buy the truck back without me having to go through the whole Lemon Law process. I was trying to be nice to the dealership and GM so they wouldn't have another Lemon Case under their belt. We all agreed it was a fair decision and I made it clear I did not expect to get back the full amount I paid for the truck. But something a little better than trade in. Which I am OK with because I put 11k miles on it. I left the dealership at 6pm. Yes I was there for 9 hours.

They called me yesterday and said they spoke with the regional rep about my truck. They said GM will not buy back the truck without me willing to get ANOTHER GM vehicle. Do they think I wont lemon this thing?? Because I will. I have tried to be patient, friendly, and understanding through this whole ordeal and that apparently does not help. Leave it to GM to complicate the hell out of this.

This is where I'm at now. Talking with the dealer and trying to get a decent price for the truck. I'll keep you all posted on this as it develops further.

JacobC1983 · April 15, 2016

They seriously told you that those with 2015-2016 8 speed trucks are basically screwed? And the 2017 model year is getting fixed? What are they putting in the 2017? The new 10 Speed that debuted in the 2017 Camaro ZL1?

brendan4862 · April 15, 2016

They seriously told you that those with 2015-2016 8 speed trucks are basically screwed? And the 2017 model year is getting fixed? What are they putting in the 2017? The new 10 Speed that debuted in the 2017 Camaro ZL1?

Yes, I sh!t you not. That is what the Service manager told me. A big middle finger to the face.