Who likes their 8 Speed?

Lgetz · June 4, 2017

My 8 spd has started torque converter shuttering. I am beyond disappointed in this truck. 7,500 miles on it and transmission clunks and shutters, leaf springs squeak like a late model F150, some unfindable rattle in front end, and stereo freezes. 2016 yr model All Terrain.

It was really nice before all of the aforementioned issues. Really considering trading. What sends me over the edge is the Amp steps I installed, Kicker sub, DVD headrest monitors...All things that I have to either let go at no value, or remove and try to sell.

I have made numerous trips to 2 dealers with yet a decent resolve. Software update for trans and stereo. Grease on springs. Couldn't replicate rattle...

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Try a different dealer. First time I took the 15 AT for shuddering they did a software update and actually got worse. Second time they replaced the torque converter and was good for a while until it began to shudder lightly. Third time they replaced the transmission filter and flushed the transmission fluid and replaced it with GM 88865601 Dexron VI. At 5+ months and nearly 3000 miles no more issue with torque converter. Your issues aren't major and have confidence another service department will make things right.

thetruck454 · June 6, 2017

My warranty is gone because of the supercharger so I had to pay for the service but I have the flush and new fluid done. What a difference the fluid makes it even shift smoother in doesn't hang or jerk as bad. Who'da thought fluid would be the problem

muhsfink07 · June 6, 2017

what type of fluid? exact model number?

mookdoc6 · June 6, 2017

what type of fluid? exact model number?

Muhsfink07 I believe I explained to you at one point how to get your 8speed inline and shifting accordingly?

thetruck454 · June 6, 2017

what type of fluid? exact model number?

https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/GLXXMobil-1-Sythetic-LV-ATF-HP?p=1

jlilnc14 · June 16, 2017

https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/GLXXMobil-1-Sythetic-LV-ATF-HP?p=1

About to have my torque converter replace, I will get them to replace the trans fluid with that one.

Bigmac · June 17, 2017

Have had my tq replaced and new fluid and still shutters. Fluid change did help for short time but it has returned. Very bad pulling my trailer. So disappointed as the rest of the truck is outstanding. Purchased specially for towing. 2017 Max tow 6.2. Trying to decide my next route to resolve this situation.

seamus2154 · June 17, 2017

About to have my torque converter replace, I will get them to replace the trans fluid with that one.

I had my TC done also. They will not put that fluid in under warranty. Only AC delco and GM fluids. Probabaly better not to document it anyway in case of a future issue. I will be putting this fluid in soon also as it is better . I already did the rear diff using Sever Gear from Amsoil. Fantastic superior fluid been using for years in all my auto with great Blackstone reports.

Lgetz · June 17, 2017

Correct Seamus the dealer will not put in Mobil 1 branded transmission fluid. They do need to use GM 88865601 Dexron VI transmission fluid on the 8 speed.

mookdoc6 · June 23, 2017

Correct Seamus the dealer will not put in Mobil 1 branded transmission fluid. They do need to use GM 88865601 Dexron VI transmission fluid on the 8 speed.

If your dealer is putting in Dex VI they are wrong on that account too. 8L90 is "HP" fluid ONLY

RockChalk05 · June 23, 2017

I have a 2016 with the 8-speed. I only have the 5.3 motor in mine but I haven't had any of the issues stated here, just over 14,500 miles on it and running smooth so far.

Lgetz · June 23, 2017

If your dealer is putting in Dex VI they are wrong on that account too. 8L90 is "HP" fluid ONLY

Made a mistake! Looked at the receipt for last time truck was at dealer and they used 21 of fluid part number 19353429. They also used 6 of fluid part number 8865601. My dyslexia saw the quantities reversed on the fluids.? Sorry for any confusion folks.

Edited June 23, 2017 by Lgetz

powerhaulic · June 26, 2017

I'm betting Dex VI would be an improvement over HP..................just sayin

Snoringbear · June 26, 2017

I'll tell if I like it or not after i get custom tune. So far i do not like the clunking every so often and the gear seaching it does once in a while. But I would still take it over a 6 speed.

2017 gmc denali ultimate 1500 6.2

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I've got the 6.2/8 spd and get the hard down/up shift every now and then, invariably when coming slowly to a stop or taking off from a stop kinda slowly. It seems it's a gear searching problem between 1st and 2nd gears, premature shifting both up and down. With the 6.2 420hp/460ft lb engine I fail to see the need to utilize 1st gear when driving in a no-load situation. I've owned trucks with manual transmissions in the past and when just dogging along I would rarely start off in what was referred back in the day as compound or granny gear. Was just a waste of time. Sooo, my suggestion is for GM to program their 8 spd (and upcoming 10 spd) to block out 1st gear unless the tranny senses a load or is in tow mode. How hard could that be?

j-ten-ner · June 26, 2017

...I fail to see the need to utilize 1st gear when driving in a no-load situation....my suggestion is for GM to program their 8 spd (and upcoming 10 spd) to block out 1st gear unless the tranny senses a load or is in tow mode. How hard could that be?

That's something I don't like on my six speed, too.

Turning a corner with the truck still rolling and it shifts down to first gear.

No need to go back into first gear above 10 km/h.

I was hoping that the new transmissions with more gears would do that.

so long

j-ten-ner