My own 8 speed problems & resolution

[Rob Okray]

Just wait for the electric truck. No tranny needed, unless you are one. 

[Crstfr]

Update.... .. finally got my truck back after 2 weeks!!!.. they were backed up in the tranny shop!. ha.. go figure... 2016 GMC 5.3 8speed.... i had the bad 1-2/2-1 clunk and the hesitation around 50-60mph... .. so they dropped it off this morning.. i havent had a chance to really drive it yet.. ..so i'll update this with the results soon.... as for the fix!.. first time, they couldnt replicate... lame!~... this time.. finally did something.... for the hard clunk shifting.. they did a TCM/BCM flash... said it required both... and for the hesitation.. they drained the tranny, new fluids and filter... 

 

i'll keep ya'll posted if this actually helped... but glad they did something... 

[Dnt]

On 2/8/2018 at 12:39 PM, rickdi321 said:

I own a 2017 denali which does the same thing, I have had it to the dealer for repair of the hard shifting at low speeds and when down shifting they did a relearn and two updates and it still clunks and does the same thing I guess thier is no fix, I'm very disappointed as ever thing else with this truck is good I just don't understand why gm . Would not fix this issue as this hurts this brand in a very competitive market for trucks  it's like they hope that looks and features  are enough and it's not true drive ability is even more important I would be afraid to buy the new ten speed 2019 model if they can't get this one right

I suspect that GM is limited in how much they can change the Trans programming that might affect the gas mileage. My 64k 17 Denail exhibits the low speed harsh downshift also. The dealer reprogrammed  it and it is slightly better but still there. Gas Mileage is great though.   

[rickdi321]

I just wanted to weight in on this yes the highway mileage  is good and sometimes  I have even got better numbers then that. But I still do not understand  why it would have to shift hard and clunk which jolts the truck randomly to get good fuel economy first of all this is low speed when it shifts hard which has nothing to do with getting good highway mileage at highway speeds my truck never has a problem then.If they were to get this truck not to do this I WOULD ABSOLUTELY LOVE THIS TRUCK and would easily recommend this truck hands down. A good company would address this issue and fix the problem my truck was very expensive and should not shift like this its A Denali 

[benelli]

4 hours ago, rickdi321 said:

I just wanted to weight in on this yes the highway mileage  is good and sometimes  I have even got better numbers then that. But I still do not understand  why it would have to shift hard and clunk which jolts the truck randomly to get good fuel economy first of all this is low speed when it shifts hard which has nothing to do with getting good highway mileage at highway speeds my truck never has a problem then.If they were to get this truck not to do this I WOULD ABSOLUTELY LOVE THIS TRUCK and would easily recommend this truck hands down. A good company would address this issue and fix the problem my truck was very expensive and should not shift like this its A Denali 

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.

[B R A D]

Update.... .. finally got my truck back after 2 weeks!!!.. they were backed up in the tranny shop!. ha.. go figure... 2016 GMC 5.3 8speed.... i had the bad 1-2/2-1 clunk and the hesitation around 50-60mph... .. so they dropped it off this morning.. i havent had a chance to really drive it yet.. ..so i'll update this with the results soon.... as for the fix!.. first time, they couldnt replicate... lame!~... this time.. finally did something.... for the hard clunk shifting.. they did a TCM/BCM flash... said it required both... and for the hesitation.. they drained the tranny, new fluids and filter... 
 
i'll keep ya'll posted if this actually helped... but glad they did something... 

I've put about 6k miles on since my flush and no problems yet. I live in North Alabama and have driven to Gatlinburg and to Mobile since. *fingers crossed

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[Crstfr]

believe it or not.. truck runs much better and added 2 mph a gallon to my daily trips... .. went up from 16.5 to about 18.2... and i'm no my 2nd tank~..

[HondaHawkGT]

On 3/12/2018 at 2:07 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.

 

Stuff like relearns, reflashing, software updates, etc are the standard way EVERY manufacturer handles customer complaints. It's been the standard procedure for years. 3rd gen Toyota Tacoma transmission flared shifts/lugging/shift hesitation/clunking shifts? Reflashes and software updates with little improvement. Ram 1500 8-speeds that develop complaints for slipping/clunking shifts/surging/flared shifts: software updates and check fluid levels with little to no improvement. Others were told "it's normal" or "no problem found". The F-150 10-speed has had all kinds of problems: grinding noises, rattling noises, knocking noises, "honking" hydraulic noises, hard shifts, clunky shifts, TCC shuddering, limp mode problems, trans pump failures, electrical glitches etc. Software updates, relearns, "It's normal", etc. No matter what brand you chose, you're going to have teething issues with new transmissions. Deal with it.

[2018GMC]

On 3/11/2018 at 5:53 PM, Dnt said:

I suspect that GM is limited in how much they can change the Trans programming that might affect the gas mileage. My 64k 17 Denail exhibits the low speed harsh downshift also. The dealer reprogrammed  it and it is slightly better but still there. Gas Mileage is great though.   

I want that Denali Cluster! I bought SLT for the Max Tow package and 3:42 gears. This is the one thing I'm missing! I've emailed Chris White http://www.whiteautoandmedia.com. They must be swamped, no response. Trying to find out what part number i need to look for to be compatible with my 2018 SLT. May have to wait awhile until 2018 Denali clusters become available. I see a few Yukon Denali clusters but i think those are different design than truck clusters.

[99Mastercraft]

I’m subscribing to this thread. I have a 2017 5.3L All terrain with 8 speed. Absolutely love the truck. Currently has 47k miles. The only thing i noticed was a random clunk when it’s cold taking off.

 

Since i don’t have much warranty left, I took it to local dealership and they are pulling the transmission pan and flushing the system.

 

They put me in a 18 Silverado 5.3L 6 speed and damn I love my truck so much more. I love the 8 speed and I hope they get their shit together. 

 

Everyone be sure to keep posting updates..

[Crobinson16]

On 3/23/2018 at 11:13 AM, 2009GMC said:

I want that Denali Cluster! I bought SLT for the Max Tow package and 3:42 gears. This is the one thing I'm missing! I've emailed Chris White http://www.whiteautoandmedia.com. They must be swamped, no response. Trying to find out what part number i need to look for to be compatible with my 2018 SLT. May have to wait awhile until 2018 Denali clusters become available. I see a few Yukon Denali clusters but i think those are different design than truck clusters.

Yea I've been looking for a 2018 cluster for my LTZ 6.2 max tow as well. There are only a few numbers out for the 18s there is a list somewhere, not sure if it's been updated to include anymore numbers for the 18s or not

 

[2018GMC]

Yea I've been looking for a 2018 cluster for my LTZ 6.2 max tow as well. There are only a few numbers out for the 18s there is a list somewhere, not sure if it's been updated to include anymore numbers for the 18s or not  

 

 

Let me know if you get any updates on part numbers or a response from whiteautoandmedia

 

[bosro]

On 3/12/2018 at 1:07 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.

Did the same....the poor service lady was very apologetic and admitted the tranny was crap but the dealerships hands were tied...

I said dont worry about it I wont have the POS for long and you will never see me again....and they havent

[FHLH]

2 cents because I’m bored.

I’ve owned 2 other cars with 8-speed autos. One was a 2014 Grand Cherokee Summit 4x4 w/ EcoDiesel the other a 2013 BMW 335i. This GM 8-speed in my 2016 Silverado behaves no differently than those Getrag units. Is it clunky at slow speeds at times? Yes... but this being my 3rd 8-speed auto vehicle I’m use to it.




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[wlezel]

I have a 2017 GMC Sierra with the 6.2 8 speed tranny... Love the truck, but I get a TERRIBLE 3-1 downshift almost every single time i'm coming to a gradual/slow stop. It literally clunks loud and surges my truck forward. It's EXTREMELY frustrating. Bought the damn thing brand new back in October last year. 

 

The dealership has checked the ECM/TCM software and both are up to date. They also performed a transmission 'fast relearn' at the 5k mile mark when they did my first service. I'm at 7k miles and the clunk is STILL there. 

 

My question to you kind folks... Does a transmission flush/filter have the potential to FIX my issue? The service guy said they only normally do that for the shuddering issue some people have, not a shifting clunk.

 

At this point i'm getting pretty desperate to fix this issue... Thanks for any input you guys have!