6.2L 8-Speed Transmission

[wurgs]

You definitely will not be disappointed with the 6.2, tranny maybe, but not the motor.

[f8l vnm]

and its not like the trans is bad in anyway , its just that its being controlled by an alien.

[BobHancock]

and its not like the trans is bad in anyway , its just that its being controlled by an alien.

Controlled by an alien....that's funny. Maybe for the '16s they'll have the alien under control. :-P

[FeelTheThunder]

7000 kms on my new ride. I have come from a 2008 6.0 - 4 spd 3.73 then a 2011 6.2 - 6 spd 3.73. My new 8 speed is definitely alien. My previous trucks shifted flawlessly.

I have had the update done without much difference, I am not sure if the adaptive learning is getting better or I am driving around the weird shifting. Even starting the truck cold it does a big shudder, I am not sure what it is.

One of the worst shifts going on is after being on the highway coming to a stop the 2-1 shift is so noticeable it almost chirps the tires. I checked the trans temp and it was 85C, normal.

The power is awesome, once you learn how to drive. On one highway approach I floored it at 80 km/hr and it must have delayed for over a second, very scary, I am not sure if it was the drive by wire or the transmission or both.

[Davidpsalt]

well its positive to hear that the 8 Speeds dont do the flair at low speed driving like the 6 speeds do.

My 14 6.2 ( Which is being bought back by GM as we speak ) during low speed driving was just awful . It would falir up and down and then just get confused after that.

Other gripe for me was the CLUNK heard when you release the gas pedal at almost any speeds

Would very much like to get your feed back on the clunk issue you had. I just bought a 2015 Sierra 1500 Denali Crew Cab and took it in for the poor shifting at low speeds - the dealer checked it out and test drove it and noticed the clunk you are describing. Mine will clunk when I accelerate then again when I let off and the engine "brakes". Annoying as hell. Brought it back this morning as they said it would be a quick fix - they swapped the drive shaft thinking it might be it but to no avail. They gave me a loaner car as they need more time to figure it out.

 

What am I in for? Bummer - $62k truck - had it two weeks and its in the shop for who knows how long while I drive a Buick Encore that feels like a Honda Civic. WTF????

[CounterMeasure]

I bet most of your banging and clunking is one or two things, or both. First, leaf springs are notorious for making noises. There's threads on it, where people (myself included) have found them not torqued properly. Secondly, the leaf springs allow a good amount of axle wrap, which results in slip yoke binding. Per other threads, I clamped my leaf springs, and it reduced both issues considerably. However, the ride was much harsher longterm, where every little bump was felt. I removed the clamps and the ride was improved, and the bumping and banging from the slip yoke came right back.

[Davidpsalt]

Thanks for the reply ... I will look into it. Disappointed that the dealer is just throwing parts at the problem vs. properly diagnosing where the sound is coming from ... I may just go pic it up and diagnose it myself on my own time. At this rate I fear they will remove the entire drive train unecessarily and I am without my ride for 3 weeks and having to cram myself into this Buick Encore while waiting ...

[GuyGene]

I'm in an F150 right now due to my last Chevy's transmission stranding me 500 miles from home! Lately I've been wanting to come back to a GM/Chevy, but, whew, no way! At least not for a while until GM gets this mess fixed for good. I'm not brand loyal, just need the most buck bang I can get since I keep my trucks a long time. Hmmm, maybe I need to find one of those great lightly used '12-14s some of y'all boys traded on ye '15s!

[Davidpsalt]

I would not steer clear because of this - my guess is that it is something simple but my dealership is addressing it in all the wrong ways. I have had no issues at all - no vibration that you read so much about and I absolutely love the ride, safety features, interior craftsmanship, 6.2L power etc. Am sure that once they figure out this annoying clang I will get many years of service out of it.

 

This Sierra Denali is basically the Cadillac escalade with GMC badging and a bed in the back.

 

We also have a 2011 Escalace ESV that is just about to hit 100,000 miles and you wouldn't think it has more that 20,000 miles on it - held up extremely well, looks and drives great - no issues what so ever ... this experience led me to buying the Sierra 1500 crew cab Denali!!!

 

Not trying to be overly optimistic - but hope it all works out in the end.

[bass mechanic]

i thought i would post an update.. i did start to have the issues people spoke of on this thread.

i got the update done and it is much better. no more problems after about 200 miles around town.

[JcMont]

 

Full disclosure: Engine and trans performance were unimpressive initially, throughout the first tank of gas. May have been because the dealer put in 87 octane (which they did do), may have been because the TCM was doing some initial learning, or may have been a combination of the two. Again, drives out great now. Love it.

 

 

 

I watched the salesman put 87 octane into my new 6.2L as well, it's funny becuase there is a sticker right there recommending 91 octane. (I didn't notice the sticker until long after)

[Tom Kyte]

I have a 1500 6.2 with max tow package. 6000 miles, about 2k of it towing a 33 foot toy hauler travel trailer. Like some of these posts, I love it and hate it. Highway mileage at speed limit is better (20-22) than my old 2013 5.3. Stoplite starts are very impressive with 3.42 gears, even though its 6200 lb normally in the truck (actual weight on scale). I took delivery last day in April. They performed the TSB then. My complaint is the shudder at slower speeds , light throttle. I was told that if the TSB trans reprogram didn't work, the next step would be replace the torque converter. My question to them was what changed in the TC. If they soften it up, I don't want it. They don't know.

My only real complaint is the 26 gallon tank and towing mileage at around 10 +/- mpg. Seems I am always looking for a gas stop that me and 33 feet can get in.

[redwngr]

FWIW, mine NEVER has a tc shudder. (and my trailers are not as large as yours, nor do I tow as often)

 

I would think that there may be some sort of defect with your tc, rather than an older/newer design. It sounds like you already have the current/latest programming.

 

Mine was built last fall, when the 3.42's were still not available for the 6.2/8speed.

[cosgood_25]

Very disappointed in the 6.2L 8sp. Engine is gnarly but the transmission and algorithm sucks. $54k for a truck I don't take my buddies in becasue its so clunky and cheap I get embarrassed!

 

1.) Does whatever it wants when cold. Hard up and dpown shifts.

2.) Violent downshift or TC clunks when crusing with very light throttle at town speeds (30-45mph). Like it doesn't know what gear to be in.

3.) Clunky downshifts when coming to a stop, pretty mush all the tim. I think it's 4-3 and 3-2.

4.) Go up a slight grade, give it a little throttle and it friggin upshifts and locks up the converter when it should do the opposite.

5.) Shutters on launch and med-hard throttle.

6.) Truck is different every day, literally. Some kinda good, some real bad.

7.) Slow, "sticky" downshifts on med throttle application like passing or general acclerating. Can almost feel it "stick". Wants to but can't.

8.) Violent downshifts on quick WOT throttle

 

Called Chevrolet within 5 days (got it in May15). "It just has to learn and your truck was built with a new, correct trans, no recalls available" They had known issues prior to Feb 2015.

3k miles: called dealer and they looked at it. "Everything checks out fine, shift pressures etc etc...just drive it more and it'll learn"

7.5k miles: called dealer again and they performed the reprogram sequence (forget bulletin #). Was a little better for a day or two, now worse than ever. Still said "it has to relearn for a few hundred miles. Don't town for a while" WTF?!

Today: got word back from GM because of my ass-reaming survey. They said take it back in and we'll see if we can make it right. A new trans is in order unless it really is a software thing they can fix, which I doubt.

 

If they don't make it right I'll be looking elsewhere and I'll take the trade in hit just to get away from this BS. Been a GM guy all my life but really starting to reconsider. Had a 2009 2500HD before this with a crap transmission as well.

 

I'll let you know what I find out.

[Tom Kyte]

2015 1500 , max tow, 6.2. Apr this year. Got the toy hauler travel trailer on it again. Just finished first leg to Myrtle Beach. Northern NJ to Virginia. First. Hill in town, felt like engine was missing. After that ran great, shifted great. Almost like I had a 8speed from cyrsler. Friend has hemi with 8speed. Maybe gm should recruit a cyrsler engineer.