Test Drove 2018 6.2 Denali 4x4 1500 - Clunky 8-Speed Transmission

chevyloco · June 29, 2018

I'm in the market for a new truck and the deals on 18 Chevy's and GMC's are looking sweet. I test drove a 2018 Denali with 6.2 8-speed transmission with 17 miles on the odometer. I only went for a short drive, but while driving around 30-40 mph on the feeder, I let off the throttle and a loud clank came from the drive line. The truck did this twice while on my test drive. My wife said, wtf was that? The salesman said, How you like it? I said, it has a drive line noise or loud clank when letting off the throttle. He said my 17 SLT 4x4 does the same thing, there is no fix. Hey, at least he was honest.

I was a long time Chevy guy. My lifted 2000 Silverado was trouble free for 13 years and 130K miles. I sold it and test drove a 14 Chevy. It had a rough idle, steering wheel vibration and the same clunky drive line. Long story short, I bought a 14 RAM Limited 4x4 and a 16 RAM Limited 4x4. Both vehicles where bought back by FCA for a defective drive train i.e. clunky downshifting 8HPZF transmission and numerous other problems. Now I'm in the market for a new truck and the prospects are not looking good. It's a shame because I really like the Denali and SLT's aside from not having rear A/C vents and the poor throttle response, the truck was super nice and dead silent on the interior.

Over the past several years I've test driven 14, 15, 16 and 18 Chevy 1500 trucks. The 14, 15 and 16 I test drove all had the rough idle, steering wheel vibration and the clunky drive train. The 18 Denali I drove only had the clunky drive train.

I was jumping ship to Ford, but it looks like owners are posting all kinds of problems with their 10 speeds as well. I'm not holding out for any hopes on the 19 Chevy's since they can't even get their 8-speed right. The prospects are not looking good for a new truck unless I want an old a$$ Tundra or an F-250 gas with the 6 speed. Can anyone make a functioning truck like the old days. I've owned numerous cars and truck and never had a problem with any transmission let alone even had a discussion about them. They just worked.

Edited June 29, 2018 by chevyloco

L86 All Terrain · June 29, 2018

No doubt there are some faults in these trucks but some are better than others. I own a 14 5.3L WT and a 15 6.2L SLT, my 14 is a piece of junk but my 15 is my favourite truck so far. The 14 has the shake and some major AFM issues causing the trans to lock up, not good.

The transmissions are a bit funky, it is all related to GM's tuning and not the actual transmission itself. You can not tune a 16+'s transmission from my understanding, at least not easily. One thing you will find with these transmission is they need to "learn" about their driver when the vehicle is new or you disconnect the battery. It can take 250-1000 miles for the TEHCM to adjust to your driving habits and shift smooth. I just finished another re-learn on my 6.2L as I park it in the winter. Shifting smooth and nice now again. There will sometimes be a funky downshift but it only happens when the trans goes to downshift and the truck switches from V8 to V4 at the same time. In all there is a bit of a learning curve for GM to go through with these new transmissions and AFM technology. It is odd, as my 2010 shifted smoother and didn't have any AFM glitches. The deal with the K2's is your going to pick out a good one, or you end up picking a pile of junk. Easy to see why they are offering 10k and 0% financing. Take one for a weekend if you're serious about buying one, put 500 miles on and see if it will be the truck for you.

Not sure what else I would buy, definitely not a pop-can truck, Ram is too cheaply built and designed although the Hemi's are great, Toyota/Nissan no way.

mookdoc6 · June 29, 2018

31 minutes ago, 10SierraA.T. said:

No doubt there are some faults in these trucks but some are better than others. I own a 14 5.3L WT and a 15 6.2L SLT, my 14 is a piece of junk but my 15 is my favourite truck so far. The 14 has the shake and some major AFM issues causing the trans to lock up, not good.

The transmissions are a bit funky, it is all related to GM's tuning and not the actual transmission itself. You can not tune a 16+'s transmission from my understanding, at least not easily. One thing you will find with these transmission is they need to "learn" about their driver when the vehicle is new or you disconnect the battery. It can take 250-1000 miles for the TEHCM to adjust to your driving habits and shift smooth. I just finished another re-learn on my 6.2L as I park it in the winter. Shifting smooth and nice now again. There will sometimes be a funky downshift but it only happens when the trans goes to downshift and the truck switches from V8 to V4 at the same time. In all there is a bit of a learning curve for GM to go through with these new transmissions and AFM technology. It is odd, as my 2010 shifted smoother and didn't have any AFM glitches. The deal with the K2's is your going to pick out a good one, or you end up picking a pile of junk. Easy to see why they are offering 10k and 0% financing. Take one for a weekend if you're serious about buying one, put 500 miles on and see if it will be the truck for you.

Not sure what else I would buy, definitely not a pop-can truck, Ram is too cheaply built and designed although the Hemi's are great, Toyota/Nissan no way.

There is learning curve much more than you would expect. The clunky is pronounced for the first thousands of miles.....and then one day it's gone? Freaking strange but I have not clunked in 50K miles?

chevyloco · June 29, 2018

3 hours ago, 10SierraA.T. said:

No doubt there are some faults in these trucks but some are better than others. I own a 14 5.3L WT and a 15 6.2L SLT, my 14 is a piece of junk but my 15 is my favourite truck so far. The 14 has the shake and some major AFM issues causing the trans to lock up, not good.

The transmissions are a bit funky, it is all related to GM's tuning and not the actual transmission itself. You can not tune a 16+'s transmission from my understanding, at least not easily. One thing you will find with these transmission is they need to "learn" about their driver when the vehicle is new or you disconnect the battery. It can take 250-1000 miles for the TEHCM to adjust to your driving habits and shift smooth. I just finished another re-learn on my 6.2L as I park it in the winter. Shifting smooth and nice now again. There will sometimes be a funky downshift but it only happens when the trans goes to downshift and the truck switches from V8 to V4 at the same time. In all there is a bit of a learning curve for GM to go through with these new transmissions and AFM technology. It is odd, as my 2010 shifted smoother and didn't have any AFM glitches. The deal with the K2's is your going to pick out a good one, or you end up picking a pile of junk. Easy to see why they are offering 10k and 0% financing. Take one for a weekend if you're serious about buying one, put 500 miles on and see if it will be the truck for you.

Not sure what else I would buy, definitely not a pop-can truck, Ram is too cheaply built and designed although the Hemi's are great, Toyota/Nissan no way.

Thanks, for the response and input. RAM kept telling me my transmission in both trucks had to learn my driving habits with 20K miles on each. Even the tech rode with me with the laptop installed and when I made immediate stops, the truck was in 3rd gear, then would hard shift to 1st gear after stopping, thus causing a hard clunk when downshifting. So clearly it was a programming issue. I've lost way to much money on my last 2 trucks even though they where bought back by FCA. I own a Lexus LS460 with 8-speed, it shifts like butter, my wife has a RC 350 with 8-speed and it's flawless, my daughter has a Q60 with 7 speed and it also shifts flawless. I need a transmission that already that's graduated with honors, not some transmission still in 1st grade if I'm paying 50K for a new truck.

L86 All Terrain · June 29, 2018

2 hours ago, chevyloco said:

I need a transmission that already that's graduated with honors, not some transmission still in 1st grade if I'm paying 50K for a new truck.

I hear ya, unfortunately no one has a perfect trans on the market right now. The big three anyway. I have not driven a late model Toyota or Nissan, perhaps you want to take one of those for a spin because I know Ford, Dodge, or GM do not have a GREAT trans at the moment. While we appreciate the creature comforts, more horsepower, and better fuel economy we are now falling behind in other categories like shifting behavior. It's pretty sad when a 1998 Chevy with a 4L60E will shift better and smoother than anything on the market today.

Frustrating I know, but it is what it is until it isn't anymore. I have HD GM's for my business and they all shift like dream, GM needs to put their HD transmission guys and/or Allison wizards to start designing the software and tunes for these computerized trannies so they actually work properly.

Good luck on your hunt, keep us posted on what you end up doing. I have a 6.2L SLT and love everything about the truck minus the odd funky decision from the trans. Under load, it shifts seamless, smooth, and damn near as fast as a Porsche PDK, it's the slow starts (leaving a stop light behind a big rig) when it seems to not know what to do.

Edited June 29, 2018 by 10SierraA.T.

Mike GMC · June 29, 2018

If I were looking right now, I'd seriously consider a gas engine 3/4 ton. Has the plain old 6.0 with no AFM and solid 6 speed. It might not have the ride or the road manners of a 1/2 ton but at least it works right. My 15 5.3 with the 6 speed has been great so far, but I can't help wanting a 6.2 for the power. Maybe some day I'll drop a 6.2 in it with the 6 speed it has. I would probably mechanically eliminate the AFM at the same time. With a proper tune, that should be about as bullet proof as a 1/2 ton can be.

seamus2154 · June 30, 2018

I have had 4 of these trucks in this platform. This platform just isn't great. My prior three were terrible, and my '17 6.2/8 speed is pretty good. Greatly improved. Seats still suck. The best years IMHO were 2007-2013. Absolute reliable good trucks. I recently considered trying to find a low mileage '13. Lane departure, backup cross saftey features, adaptive cruise, backup camera, vibration alerts in the seat, and low speed accident avoidance are pretty good reason to stay. But the 8 speeds have gotten better, I have not one issue but the occasional clunk coming to a stop but back on gas then clunk. I would do an 8 speed before a 10 speed right now.

kylant · June 30, 2018

i have an '18 6.2, 8 speed. just turned 500 miles today. so far, tranny is smooth as silk

FL335i · June 30, 2018

Chevyloco- Your conclusion about trucks currently is exactly what I've been thinking. My '14 is doing pretty well, the 6spd is not bad as long as the fluid is kept super clean. But if I had to buy a new 1/2 ton right now.... man that would be a tough decision. I'd probably look long and hard at the new Titan. Aisin transmission, proven gas engine, large rear axle, not a 1st year run.... Fantastic warranty and great price.

Donstar · June 30, 2018

13 hours ago, seamus2154 said:

The best years IMHO were 2007-2013. Absolute reliable good trucks.

I really liked my'09 which is why I bought my '15. I wanted to refresh my truck and buy one that was similar. I find the fit and finish so much better on the '15 and the interior is a huge improvement. My '15 has been trouble free for the first three years whereas my oil burning '09 spent a lot of time having warranty work during its first three years. GM made it right which is part of the reason for continuing with their product. If my transmission or any other part of my truck was clunking unpredictably or malfunctioning I would take it in for warranty repair. These trucks are designed to run smoothly and work hard. I think Op should test drive another GM truck and find another salesman. I get suspicious when a salesman of a major product says they have the same item at home.

TXGREEK · June 30, 2018

I really liked my'09 which is why I bought my '15. I wanted to refresh my truck and buy one that was similar. I find the fit and finish so much better on the '15 and the interior is a huge improvement. My '15 has been trouble free for the first three years whereas my oil burning '09 spent a lot of time having warranty work during its first three years. GM made it right which is part of the reason for continuing with their product. If my transmission or any other part of my truck was clunking unpredictably or malfunctioning I would take it in for warranty repair. These trucks are designed to run smoothly and work hard. I think Op should test drive another GM truck and find another salesman. I get suspicious when a salesman of a major product says they have the same item at home.

I ordered my 18 SLT with the 6.2 and a standard bed, cake with every option minus electric running boards and magnetic ride as per my off-road guy suggested. 7K miles on mine and absolutely ZERO problems. I’ve bought new trucks every two years with this one and my 16 DMax being the best riding out of all of them.

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chevyloco · June 30, 2018

15 hours ago, Mike GMC said:

If I were looking right now, I'd seriously consider a gas engine 3/4 ton. Has the plain old 6.0 with no AFM and solid 6 speed. It might not have the ride or the road manners of a 1/2 ton but at least it works right. My 15 5.3 with the 6 speed has been great so far, but I can't help wanting a 6.2 for the power. Maybe some day I'll drop a 6.2 in it with the 6 speed it has. I would probably mechanically eliminate the AFM at the same time. With a proper tune, that should be about as bullet proof as a 1/2 ton can be.

I've been throwing around the idea of a 3/4 ton for that reason. I love the ride of the 3/4 with torsion bars and the 6 speed. The only reason I might not get a 3/4 ton is I like to park my truck in the garage.

chevyloco · June 30, 2018

8 minutes ago, TXGREEK said:

I ordered my 18 SLT with the 6.2 and a standard bed, cake with every option minus electric running boards and magnetic ride as per my off-road guy suggested. 7K miles on mine and absolutely ZERO problems. I’ve bought new trucks every two years with this one and my 16 DMax being the best riding out of all of them.

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How was your transmission when you 1st bought the truck. Did it shift smooth? The salesman who helped me said his clunked and they where not able to fix it. He has a 6.2 SLT as well.

Edited June 30, 2018 by chevyloco

Mike GMC · June 30, 2018

1 hour ago, chevyloco said:

I've been throwing around the idea of a 3/4 ton for that reason. I love the ride of the 3/4 with torsion bars and the 6 speed. The only reason I might not get a 3/4 ton is I like to park my truck in the garage.

Is it too tall for your garage? You can always build a bigger garage, who wouldn't want that anyway?

TXGREEK · June 30, 2018

How was your transmission when you 1st bought the truck. Did it shift smooth? The salesman who helped me said his clunked and they where not able to fix it. He has a 6.2 SLT as well.

The 6.2 does have a clunk from time to time but nothing that would send me running to the dealership. I knew this while I was looking into the 6.2’s and doesn’t happen everyday. Take in mind, the performance of these trucks is awesome, nothing can really compare to these trucks so if you’re debating about buying one, no brainer for me, jump on it with all these rebates and discounts. The overall performance of these trucks are absolutely awesome, (aside of diesel) tow excellent, best truck in its class. One of my sponsors, the owner of a large GMC Chevy store flat out told me that one day it’s going to be an easy fix either from GM or from local shop and even the new trucks always have issues no matter the brand.

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