Who likes their 8 Speed?

[jlilnc14]

Just had my 2015 sierra 6.2 8 speed at the dealer today there's a new bulletin that came out 1/20/17 16-NA-411 for hard shifts, clunks , v4 to v8 banging noise in trans so far so good we'll see.

Do you know what was done? Reprogramming? Something done physically to the trans?

[n1ghtsh1ft]

I think that TSB is only for 15 and 16 model years. I wasn't able to find anything matching for 17 model years. That being said, I did notice that the loaner 2017 6.2 8 speed I had for a short time had a defined kick when downshifting to gear 1. My new 2017 5.3 8 speed is smooth like butter.....although I only have 900 miles on it, time will tell.

[m3n00b]

my 8 speed works good, only thing is if you stop real fast it will kick you in the butt when it shifts fron 2nd to first. i just learned how to keep it moving till it shifts all the way down.

I fixed this by driving 5 miles in m6 between 1100-1500 rpm

 

C1 relearn outlined here.

 

 

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

 

-tapa

Edited February 6, 2017 by m3n00b

[Lgetz]

After an extended drive on Sunday and about 250 miles since getting the AT back from dealer all seems good. No more shudder felt between 62-72 miles per hour under light load. Will keep everyone updated.

[mookdoc6]

good to hear!

[Boardmember]

Wife said today: if your transmission can't be fixed, at about 35k miles you need to trade this truck in...

[Malibuair]

I just bought a 2016 GMC Sierra SLE used with 2,800. My previous truck was a 1999 Chevy LS Z71. 4 transmissions at 280,000. I bought the new one thinking there is no way GM has not fixed that problem...My biggest complaint about the Sierra is electronics. The throttle response is horrible. Sometimes snappy other times it falls on its face. Seems to do exactly what you don't want it to do. Also, when going up a small incline if you're not careful the shift to 1st is horrific. Huge clunk shakes the whole truck. Most shops say it because of modern transmissions. Blaming computers on shifting timing. If you pull the fuse to the stabiltrack it helps. Frustrating, I know it's just a truck but my 99 would smoke my new one 7 out of 10 times. I tried a hyper tech programmer. Didn't change any of the unpredictable lag. Is there a clean way to remove all electronics with a switch on the dash? I know you can pull the fuse (or interrupt the circuit with a switch) to the stabiltrack but it flashes errors on the dash. I'm an electrician so I understand basic circuitry. Is it possible?

 

PS

 

If we are adding switches, what about a switch to lock the locker on the dash?

[hawkeye4jw]

Will be taking mine in next week for the trans shudder. Mine does it at occasionally in any speed. They want to do a flush and something else first to see if that fixes it. If that doesn't fix it, then they will replace the torque converter. Luckily, I know the mechanic that will be doing the work, so I know exactly what will be done.

[dodge stomper]

I have a 16 5.3 8 speed and have the same Trans issues. I had the Torque Converter replaced a few months ago and it did get better. I tow a 9k pound RV and am generally happy with the truck. What does piss me off is the Catch Can issue.... Someone else said it but after paying 53k for a new truck we should not have to do anything to it! If they know there is a Catch Can issue they should address it, AFM address it.... I am not rich but like most am a hard working man who has looked forward to having a truck like this and have no problem paying 6 hundred bucks a month for the privilege.... But GM should be embarrassed!

 

But hey, this is the new world we live in..... On a side note going in to get the Bow-Tie illumination option installed this morning.

 

Great Site here...

 

Kudo's

 

Keith

[Threerun]

I have the 6.2 8spd in a 2016 and it shift like butter. You literally have to watch the tach in order to tell the shiftpoints above 2nd gear. In fact- this is the best motor/tranny combo I have ever owned, including one CVT in a Toyota.

[mookdoc6]

CVT? Really? I can't even describe how much those things want to make me kill somebody! Maybe they are better now.....

[Threerun]

CVT's and hybrids are pretty well paired. Very linear torque curve.

[nfd78910]

Had my truck in for the second time for the hard shifts and clunking. The first time they did a relearn. The second time the tech acknowledged the shifting behavior, but said that they discussed with GM and said it was completely normal.

 

Cool.....

[Dnt]

At 4000 miles now 2016 6.2 8spd. Smooth as silk loving it. Somewhere earlier in the is thread someone mentioned that there is no longer a transmission dip stick i will have to check on that. Sounds weird LOL

Update at slightly over 14,000 miles now. 8spd shifts very hard, getting a tire chirp in 2nd 3rd and 4th and 5th sometimes. That is the way i have set the programmer LOL. I may set it back for girly shifts in a few days...... too bad GM did not have the marketing sense to provide owners with driver selectable driving modes. The 6.2 8spd combo dang sure deserves

[muhsfink07]

i have an appointment for saturday morning to address the hard shifting. for the 3rd time... i will keep everybody posted. i am going to bring up the printout from another memeber that identified my problem exactly and they replaced the Torque converter to fix