Any one with the 8 speed not having issues?

conundrum · November 11, 2019

'19 still pretty new, no issues so far.

Sparkplug · April 13, 2020

On 9/25/2018 at 4:22 PM, Canyon Conundrum said:

Any one out there with the 8 speed transmission not having issues??

Just thought I would throw that out there to see how many are having problems and how many are not.

Thanks

My 2017 had the shudder at 7000 miles. I never questioned what the dealer did, as it has not in the 57,000 miles since acted up. Come back. They supposedly changed the torque converter, and reprogrammed the computer. I lost about 2 mpg, afterwards. I even added a chip. My brotherinlaw had a 2017 Silverado Z71, that had an 8sp in it, that he had GMs lemon law used on. Mine shifts on the 1-2 shift hard at times as well as downshift at times. I like a firmer shift anyways, but not the bang in. Reverse is hesitant on cold start up. As far as programing goes you will have to live with it. I was going to have a chassis tune, done, and found out the COMPUTER was LOCKED and had to be unlocked first. But thats GMs control, over you

jim47 · July 3, 2020

Had a 2017 Colorado Zr1 two years I owned it it was in the shop a total of 54 days same problems down shift hard in low and shifted hard out of low they did everything but replace it and nothing helped. Got tired of messing with it bought a Toyota TRD Spot 4x4 put 900 miles on it after 5 months I traded it in on a 2020 Colorado Zr1. Only have 200 miles on it I hope I have better luck this time.

Canyon20 · November 6, 2020

So here is what I know about the transmission issue. Supposedly beginning in 2020 they switched transmission fluid to solve issue with fluid sucking up moisture. Original fluid would act like brake fluid. This would cause issue with corrosion in TC and clutch slippage.

My 2020 was starting to look like it too was going to have the same problem, but what I have being doing the last week is taking the pups for 2-3 hours drives on freeway, mountain roads and overall constant runs without stopping for 30 minutes minimum. I took my time and care when breaking in the engine for the first 1000 miles, but that does not help the tranny learn what it needs to know. Now that I have 1600 miles on the truck I am taking these long runs to allow the control system to learn about the drive train.

Results have been mpg`s running in the 17-19 now running around 25 mpg. I am getting around 25.5 at 75mph on the freeway. Transmission has been learning as well. Downshift from 3-1, 2-1 are now smooth as silk. If roughness comes back, I will go to dealer and have the perform the C-1 clutch relearn. I am attaching bulletin on this. So when dealer says the transmission needs to learn how you drive, on a new truck there is truth to this, but just do what they recommend and make sure you take long very mixed condition runs and give the tranny time to learn. On trucks with more miles and you have had the oil issue addressed and possibly the TC changed, make sure to bring up the service bulletin. I attached it because frankly, not all dealers do their homework and miss this bulletin.

Other than the Infotainment glitches, that GMC says only happens on 7" screen systems, My Denali has been performing as expected.

MC-10169298-9999.pdf

SILVER SLED · November 6, 2020

I liked my 18 6.2 8 speed trans more than my 21 6.2 10 speed.

glcbn · January 31, 2021

Wife's new vehicle is a 2021 Colorado! Z71. Right now it has only 1,200 miles on it. So far, I haven't noticed anything out of the normal.

Edited January 31, 2021 by glcbn

madcratebuilder · April 22, 2021

Mine was strange during the 500 mile "learn" period. I use the Trifecta tune and trans performance is perfect. 2017 ZR2 8l45.

madcratebuilder · July 23, 2021

My 17 ZR went 3.5 years before the first shudder. I got the flush done right away and it's been smooth for the past six months. To much driving with the shudder can damage the torque convertor.