My own 8 speed problems & resolution

cev103 · August 10, 2016

I'm just curious.....is it mostly trucks with the 6.2L engine, or is this more of a global problem that includes the 5.3L engines as well? I only ask because from what I can tell is that most of the people commenting on this thread seem to have the 6.2L w/ the 8 speed transmission.

CounterMeasure · August 11, 2016

Its the 8-speed in general. Most of the complaints come from 6.2 owners because all 6.2 pairings for '15 and '16 include the 8-speed.

I'm just curious.....is it mostly trucks with the 6.2L engine, or is this more of a global problem that includes the 5.3L engines as well? I only ask because from what I can tell is that most of the people commenting on this thread seem to have the 6.2L w/ the 8 speed transmission.

huntr1117 · August 12, 2016

My problems seem to occur at very low rpm 1k-1.5k SPEEDS 30-45. Hesitation, some what jerky at times, like it is hunting for the right gear but can't seem to find it. The Tach also seems to flutter with a constant foot on the gas. And occasional clunk or hard shift.

Anybody else having similar problems?

Looks like they didn't fix these issues in the 2017 model. My 6.2 with the 8 speed is a 2017 and seems to be doing the same thing. If I stomp on the accelerator it does nothing. Kinda like the converter is stumbling trying to lock/unlock. The truck only has 400 miles on it now so I'm hoping it needs time to break in.

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Dndodd · August 12, 2016

Looks like they didn't fix these issues in the 2017 model. My 6.2 with the 8 speed is a 2017 and seems to be doing the same thing. If I stomp on the accelerator it does nothing. Kinda like the converter is stumbling trying to lock/unlock. The truck only has 400 miles on it now so I'm hoping it needs time to break in.

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I agree my truck now has over 1400 miles on it and continues to get better. Interestingly since I put Bilstein 5100's on it seems to have gotten better but I think I need more miles on it to confirm that is the case.

Rme2513 · August 13, 2016

I have been threw all of this since I bought the my truck in November of 2014 lots of problems beside the transmission it has been replaced and updated and valve body work all has made it better but it still does not perform like it should but it works I did not want to go threw the lemon law so I just said it is what it is and everyday multiple times while driving it does something stupid but it works so I'm keeping it it's paid for one thing that has helped me is to stay off this site reading all this just makes it worse and I want to drive it to Detroit and park it in there office but instead I just stay off here and hope the next time I buy a truck I can make a better choice hopefully GM will get this right but if the don't there's always FORD if there 10 speed is not junk to

silver sled 16 · November 3, 2016

2016 gmc sierra 6.2 8 speed. I too am big gm fan. Have had many. This truck with the exception to the power of 6.2 is a p.o.s ... transmission is garbage. Engine is very noisy and idles like it wants to stall. Rides like a hosre. All for almost 60 grand. I'm sure it's not all of them but too many where there is a big problem here. On my second converter. Many relearns. I too would rather drive my old car than this new one. Headed for lemon law. Gm has had their shot.

Srode1 · November 13, 2016

The dealers should be using the rapid learn mode for the specific problem shifts per this bulletin to correct hard or flair shift problems. If they aren't just starting relearn over won't do anything

http://gm.oemdtc.com/492/transmission-adaptive-functions-and-correcting-low-mileage-harsh-shifts-2015-cadillac-chevrolet-gmc

Dcollins25 · November 20, 2016

Get your stater support shaft changed in the 8 speed and it will get way better. Had it done a month ago and I would call it 95%

4emeryj44 · November 20, 2016

Get your stater support shaft changed in the 8 speed and it will get way better. Had it done a month ago and I would call it 95%

Is that some sort of FIX that GM put out? Who made that call? I've had multiple engineers out and a transmission replaced and relearns and new valve bodies, etc..... nobody has ever mentioned this.

Dcollins25 · November 20, 2016

It was a gm update. I usually bring it in every 3months and ask for all the bulletins and updates.

4emeryj44 · November 20, 2016

It was a gm update. I usually bring it in every 3months and ask for all the bulletins and updates.

must have been within the last 2 months because I had an engineer all over my truck for a week. What kind of symptoms were you having? Similar to what we all have been having? I'd like to know this because I do love my truck, if it shifted way better I'd prefer to just keep it.

4emeryj44 · November 20, 2016

It was a gm update. I usually bring it in every 3months and ask for all the bulletins and updates.

Do you have a TSB or something to post have so I can research?

Dcollins25 · November 20, 2016

I was the same as u. I had considered trading it in on a Ford....yuck. the only time the truck acted somewhat normal was when it was in tow haul. The werid shifts and chunks when taking it easy and then accelerating. The bangs when down shifting at stop signs. 95% gone since the stater support shafts update.the new torque converter did noting.

4emeryj44 · November 20, 2016

I was the same as u. I had considered trading it in on a Ford....yuck. the only time the truck acted somewhat normal was when it was in tow haul. The werid shifts and chunks when taking it easy and then accelerating. The bangs when down shifting at stop signs. 95% gone since the stater support shafts update.the new torque converter did noting.

Wow that is some great info, I wonder if that's the end all be all of fixes for all of this? That would explain why multiple people including myself had replacement transmissions that just never seemed to make much difference. Is that what they fixed for the 2017's? Again, look at my latest post if you have the time. Why would GM lemon law their own truck, and crush a truck if that was the fix for it?