Who likes their 8 Speed?

jimmyboy8301 · August 26, 2017

Couldnt agree more. I just traded into the 2017 6.2/ 8 speed and can say this is much better than my identical 2015 setup. It isn't perfect but better. I agree in town driving, parking lots, and slow is where the issues are. Which is just tuning. Because off the light in a straight line it shifts perfect. Towing is where it really shines. Dropping to just 7th or 6th is so smooth and a pleasure towing. I have gotten 15 mpg towing at almost 80 mpg on flat roads here in Fla. Done even better at 70 mph. That is diesel towing mileage if not better. Don't know why but it is true the more you beat on it the better it shifts?

it seems it definitely shines under load, but the minute you back off it's a little jumpy.

2017 Chevy Silverado LTZ Z71 6.2L

4.5" Zone

22x10 AF Grips

33x12.5 Nitto Ridge Grapplers

Instagram @wildchevys

seamus2154 · August 27, 2017

it seems it definitely shines under load, but the minute you back off it's a little jumpy.

2017 Chevy Silverado LTZ Z71 6.2L

4.5" Zone

22x10 AF Grips

33x12.5 Nitto Ridge Grapplers

Instagram @wildchevys

Exactly, it never seems ready for anything but going forward at steady throttle. Anything else is a surprise to it and it stumbles and handles it badly! Worst is if you are a bit heavy on throttle from a stop and it shifts through 4-5 gears then you just release the pedal, it actually hangs, almost slips, and doesnt upshift or downshift!! Like a deer in the headlights. Very annoying because it is such a good trans in other ways, it is just tuning that GM clearly was not dedicated to doing.

mookdoc6 · August 27, 2017

A couple weeks ago I dropped 700Lbs of Steel in the bed and I thought this will be interesting never had this much back there? Wouldn't you know it those longer shifts we all F'N hate from 1-2-3 are utterly beautiful with some weight back there! I have not towed with the 8speed but driving the hills and straining the little pecker it's freaking SPOT ON! It's totally geared for towing I believe......

I could have checked into the psych ward in the first 5-10K it was that mind controlling......Now it just keeps getting smoother other than the first couple sticky shifts in the morning which GM told me it's the computer Holding line pressure from the last drive? Does not hurt anything just takes 2-3 shifts every morning to smooth out? Anyway, I feel for many of you and just keep driving it eventually it gets better!

BobHancock · September 1, 2017

Just traded into a 2017 Denali 6.2l 8 speed and it's perfect. Smooth shifting all the time. Much better than my 2016 Chevy.

Dnt · September 1, 2017

Got an appointment with my local Buick GMC dealership to do my first oil change / rotate tires and "hopefully" FIX the clunky transmission on Monday (ECLIPSE DAY),

My Clunky 8spd Trans seems to be getting worse. When first started in the morning and putting into reverse it SLAMS into gear, at almost every slow roll coming to a stop it SLAMS into a lower gear really feels like someone hit the back bumper. It hunts for gears at low speed like it has no sense at all. Totally unacceptable. Makes me wish I had my 2016 6.2 8spd back. The 2016 only had a rare event of harsh downshift once in a while, this 2017 is Ridiculous. Will try to remember to report back. They will fix this or I will be driving a different truck in a few weeks. I am not going to put up with BS on a +64k sticker vehicle....

About 1 1/2 weeks since the trans update and I am happy to report that it actually is much better. Still has an occasional episode but it is rare now. I will drive it a few months and see how it does.

cjhrph · September 6, 2017

Not me. 2017 here. 6.2/8 Sp. Same issues. LOVE the truck and the 6.2, transmission is possessed at low speeds, turning, coming to a stop etc. Clunks, Harsh Downshifting, Surging. No problems when your on the gas though, impressive, smooth as silk. Just had TCM update from the PIP5437B bulletin applied at 600 miles. Not sure it did much. Ill give it short to while to "re-learn".

Update. 1050 miles now and trans seems to have learned quite well. I am pleased to report that the previous problems are very few now. The PIP5437B seems to have resolved the problems. The truck, with the 6.2 and the 8sp is a beast.....very happy.

mayfieldjeff · September 7, 2017

i had a 2015 Yukon Denali with the 6.2 8 speed and had nothing but problems with it at the start. i had a shutter that happened in between every shift. at 17k miles they replaced my entire transmission because they couldnt actually pin point the issue. sure enough 17k miles later started happening again. this time they said they now know the issue and its the torque converter. so they replaced that this time and luckily hadn't had an issue since. but then my A/C compressor went out at 60k miles. so i had enough with that vehicle and traded it in for a 2017 Sierra Denali 6.2 8 speed. hopefully i have better luck with this one.

seamus2154 · September 8, 2017

i had a 2015 Yukon Denali with the 6.2 8 speed and had nothing but problems with it at the start. i had a shutter that happened in between every shift. at 17k miles they replaced my entire transmission because they couldnt actually pin point the issue. sure enough 17k miles later started happening again. this time they said they now know the issue and its the torque converter. so they replaced that this time and luckily hadn't had an issue since. but then my A/C compressor went out at 60k miles. so i had enough with that vehicle and traded it in for a 2017 Sierra Denali 6.2 8 speed. hopefully i have better luck with this one.

same here. 2015 Denali XL. Replaced torque converter, replaced stator shaft, flush fluid, 4 reprograms of TCM, new radiator, New thermostat, new condenser, new steering shaft bearings, new seat track after 3 fixes. I am not buying a Ford or Dodge, just traded into a 2017 Denali XL and so far it is nicely improved, shifts fine, but still a little confused at slow speeds, but overall MUCH better than the 1st year 2015!

Dmf10e · September 26, 2017

Is there any way to set the trans to "re-learn" mode manually without having to go to the dealer for it to be done?

Snoringbear · September 27, 2017

Is there any way to set the trans to "re-learn" mode manually without having to go to the dealer for it to be done?

I was listening to a local radio show last Saturday, The Car Pro/Jerry Reynolds; and in answer to a caller on a related topic he stated that if you disconnect your battery for about 30 minutes the tranny will revert to Learn Mode. Haven't personnaly tried it though. He did say something else I thought was interesting; he said that a lot of folks tend to drive their new vehicle more gingerly when they first buy it than they normally drive. He said that's a mistake as the tranny programs itself based upon your new car driving, then when you revert back to your normal habits the tranny is confused and thus does not perform satisfactorily. So, bottom line, drive your new car normally, don't baby it

Dmf10e · September 27, 2017

I was listening to a local radio show last Saturday, The Car Pro/Jerry Reynolds; and in answer to a caller on a related topic he stated that if you disconnect your battery for about 30 minutes the tranny will revert to Learn Mode. Haven't personnaly tried it though. He did say something else I thought was interesting; he said that a lot of folks tend to drive their new vehicle more gingerly when they first buy it than they normally drive. He said that's a mistake as the tranny programs itself based upon your new car driving, then when you revert back to your normal habits the tranny is confused and thus does not perform satisfactorily. So, bottom line, drive your new car normally, don't baby it

Saw someone else's post referring to that. Thought I'd give it a try and reset it and drive like I stole it! Hopefully that will fix the sluggish issues I'm having. Thanks!

mookdoc6 · September 27, 2017

Saw someone else's post referring to that. Thought I'd give it a try and reset it and drive like I stole it! Hopefully that will fix the sluggish issues I'm having. Thanks!

Sir, Please disconnect your battery and allow 1hr! Also, while your doing that take apart the Intake and remove the plastic piece with Mass air flow sensor or the piece with the electrical plug attached. Careful on the clip it will break easily! Do not touch MASS Air Flow sensor just look at the X or + plus shaped plastic that holds this in place as In looking through a roll of toilet paper. If there is ANY FLASHING AT ALL AROUND ANY OF THE EDGES AND CORNERS REMOVE ALL FLASHING AND CLEAN IT and reinstall.

Drive truck with a little more foot into it! After a couple thousand miles it will be 100% better!

Dmf10e · September 27, 2017

Sir, Please disconnect your battery and allow 1hr! Also, while your doing that take apart the Intake and remove the plastic piece with Mass air flow sensor or the piece with the electrical plug attached. Careful on the clip it will break easily! Do not touch MASS Air Flow sensor just look at the X or + plus shaped plastic that holds this in place as In looking through a roll of toilet paper. If there is ANY FLASHING AT ALL AROUND ANY OF THE EDGES AND CORNERS REMOVE ALL FLASHING AND CLEAN IT and reinstall.

Drive truck with a little more foot into it! After a couple thousand miles it will be 100% better!

Thanks for the pointers. I'm not very familiar with this area so not too sure which is the intake or where the Mass airflow sensor is located. Do you have a pic or link showing the area you want me to take a look at?

mookdoc6 · September 27, 2017

Thanks for the pointers. I'm not very familiar with this area so not too sure which is the intake or where the Mass airflow sensor is located. Do you have a pic or link showing the area you want me to take a look at?

The big plastic box with the engine air filter...Yup, take that off from the electrical connection and read instructions above if it looks like it's super clean edges/crisp don't worry....if any residual flashing anywhere on the + or X molded plastic remove all material to clean edges...sand with fine paper 600 and clean with damp towel and let dry

Snoringbear · September 28, 2017

The big plastic box with the engine air filter...Yup, take that off from the electrical connection and read instructions above if it looks like it's super clean edges/crisp don't worry....if any residual flashing anywhere on the + or X molded plastic remove all material to clean edges...sand with fine paper 600 and clean with damp towel and let dry

I too say thanks for the tips. I think what Dmf10e and I would like to know is what role the flashing and such plays with the tranny shifting problems. I also find the "+ or X" part confusing. Anyway, if you could give a little more detail I think we would both be appreciative. Thanks, SB