Who likes their 8 Speed?

Jtodd · August 28, 2016

HATE IT!!!!!!2015 SLT 6.2 8speed....never has shifted right...hard shifts and clunks...8 times in shop...2 new trannys,...torque converters...and TCM modeles ...hard shifting has improved...but the clunking has not....field tech..worked on it and test drove it for 30 days and 700+ miles

Dnt · August 28, 2016

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

publicalias · August 28, 2016

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

Not for the 8spd. I was showing my kids all the fluids they should check while we were changing the oil and said, "... and the transmission... Uh, where'd it go!"

Sent from my Nexus 5X using Tapatalk

CptMcSaug · September 7, 2016

Well, had a new converter put in and just made my shuddering worse. Taking her back in and getting the whole tans replaced. Maybe that'll fix it.

Bikemobile · September 7, 2016

2017 5.3 Gmc Sierra Slt 4x4 8 speed here. I test drove a few 16's on the lot and they shifted very harshly and clunked when coming to a stop. Test drove my 2017 and it was smooth. Shifts up and down smoothly, no clunks no harshness. Maybe the 17's have the new parts/programming?

BlueCrayon · September 20, 2016

2016 6.2L 8 speed.....95% of the time I really like it, shifts smooth yet firm enough. Actually, I find it upshifts quite well, it's the downshifting that can sometimes be an issue. When you get on it, sometimes I feel it's sluggish to drop gears, but much more importantly it does have that hard clunk downshift every once in a while when coming to a stop.

groutguy · September 22, 2016

2015 6.2l Denali. Shifts really well, has the rare but occasional harsh 2 -1 downshift.

As stated above, the downshift on passing is a little sluggish. Never had any issues on the up shift.

thetruck454 · September 22, 2016

Mine at around 10,000 miles started to shutter. It happens when the torque converter locks/unlocks constantly during light throttle cruising. Now at roughly 14,000 miles it really likes to lunge forward when comming to a stop. Since I'm supercharged I have about a 0.001% chance they will warranty it. I'm still gonna try to bring it in and see how the dealership handles it. Worst case I lose warranty and I need to buy a trans/Tc and install it myself. I've done them on previous trucks, let's hope this one doesn't require special tools.

galliher_nc · September 22, 2016

I don't love or hate mine. It clunks around still, but it has smoothed out some over time and is still better than my 6 speed ever was. When I put my foot to the floor, I love it. Shifts out real nice. Around town, not so much.

I have just shy of 18,000 miles on mine.

rmw04c · September 28, 2016

New member here but a long time visitor to this site. Had to comment on my 8 speed. I have a 2016 Sierra SLT CC 4x4 5.3 and 8 speed. I have owned four GM trucks, three bought new one used.

The trans on this one is by far the harshest shifting tranny I have ever had on not only a GM vehicle but any vehicle. LOVE the truck except for the trans. Hard shifting, usually downshifting, but upshifts hard with a light throttle. By far the most annoying is when slowing down to stop right before coming to a complete stop is annoying bump/jerk feeling. Almost feels like some one ran into your rear end at slow speed. Have tried the grade braking turn off trick but no change...I think it mainly works for the 6 speed. BTW I had the same 6l80 trans in a 2009 Avalanche and it was butter smooth. I personally feel the tranny is good just the programming is very poor.

I have had these issues...basically everything in this entire thread. I have a 2015 Denali, and at 17,000mi the dealership replaced the transmission. It is even WORSE after this has happened. I issued the final repair notice to GM after having the truck in the shop 9 times in the first year - they told me to pound sand on the final repair attempt and denied the issue even exists. I get shudders, hard shifts, lurching at low speeds, LOUD clunking...the works. It is insane - criminal - that they are allowing this to happen to people with these 8spd transmissions. Their customer service is HORRENDOUS, and has put me into the system and has circulated me for months without doing anything.

They offered an extended warranty - but what's the point if I have to come in to the dealership 10+ times a year? The truck not only causes serious safety concerns, but costs me hundreds of dollars by having to go to the dealer (50 mi away) for service. This truck is a complete sham. I am shocked that an American company would screw over so many Americans. I know we're not the only ones - just the only ones on the forums talking about it.

Has anyone else had any luck in resolving the issues permanently? Whether through a new 2016/2017 that doesn't have the issues, or ANYTHING that fixes this? I feel like I'm going insane here.

Jerry's Denali · September 28, 2016

2016/2017's trans having issues also, mostly delayed engagement and shudder.

GM customer service is the worst I have ever witnessed.

Probably why Mary Barra still drives a MB SL550.

Edited September 28, 2016 by JEB1966

ecmoney · September 29, 2016

I have a 17 with 400 miles..Its a 6.2 slt 8 speed....No problems with mine, it was build about 3 weeks ago!

Snoringbear · September 29, 2016

I have a 17 with 400 miles..Its a 6.2 slt 8 speed....No problems with mine, it was build about 3 weeks ago!

I'm happy with my 2015 6.2/8spd, have about 24k miles on it. Just recently had my last "free" oil change. About the low speed shift problem; I too had the occasional rough shift going from 1st to 2nd and when coming to a stop from 2nd to 1st. Had the tranny checked out at my last oil change. Nothing was found wrong. So, they reset the learning feature back to factory setting. It shifting smoothly now, both up and down. Where the 6.2/8spd combo excels though is when towing. I pull a 6,200 lb TT occasionally and I absolutely love it. Lots of hp and torque, 8spd tranny keeps the engine in the sweet spot. Happy, happy camper