Who likes their 8 Speed?

[Snoringbear]

Reading through this thread it seems to be a total crap shoot whether the truck tranny misbehaves or not. My 2016 Chevy with 6.2/8 got better over miles but never right. Only way to make it good was run in tow haul mode which just holds the shifts. Now my 2017 6.2/8 is perfect. No tranny shifting issues at all in noodle or sport mode. It's a mystery.

I towed my 6,000 lb TT to a camp out two weeks ago, about 250 miles each way and my 6.2/8 spd shifted smooth as a gravy sandwich while towing. Actually, it seems to shift smoother since I've returned as well.

 

Btw, I gave an opinion for a fix several pages back; that being for GM to design the 8 spd and upcoming 10 spd so that 1st gear is disabled when being driven in a no-load condition. 1st could be activated by pushing the tow button. Interestingly, a guy responded stating that his Mercedes has that feature. Said 1st was disabled unless sport mode was on or he floored it. Maybe GM will do something like this too. When no load driving the 6.2 which has 420 hp / 460 ft lbs torque doesn't need 1st gear to get the truck rolling.

[j-ten-ner]

...that being for GM to design the 8 spd and upcoming 10 spd so that 1st gear is disabled when being driven in a no-load condition. 1st could be activated by pushing the tow button....

 

At least leave the trans in second gear as long as the truck is moving.

Only shift down to first after the truck's come to a complete stop.

Nothing more annoying and unnecessary than turning a corner and having the trans shifting into first.

 

so long

j-ten-ner

[Srode1]

Also, torque converter shudder raised its ugly head at about 32K miles. Took truck to dealer and problem was confirmed. Fix was a complete tranny flush with new type HD fluid including tranny cooler (23 Qts LV fluid) and new filter. Plus tranny reprogram. This fixed the torque converter shudder problem. Btw, there's a service bulletin on this. And, the notorious low speed 2nd > 1st and 1st > 2nd hard shift is now less severe. However, the biggest improvement has been the tranny's retraining of me. When I make what was referred to way back in the day as a California Stop and only slow to about 3 ~ 5 mph I sometimes get the hard hitting shift from 2nd to 1st which I hate. But, if I come to a complete stop at the stop sign and look both ways like a good boy the tranny works fine. Sooo, I now am resigned to obeying the law and making full stops, problem solved, lol

That's encouraging to hear - torque converter shudder showed up on mine a few weeks ago at 26,000 miles, and I just got it back from flush and filter change, refilled with 19353429 fluid. They said drive it 200 miles and if it doesn't fix it bring it back, its fixed right now but time will tell if it stays fixed. It does shift smoother but I haven't really put many miles on it - no reprogramming was done. Bulletin 16-NA-175 document 4526930 was listed on the paper work.

 

I rode in an '18 Camaro 6 cylinder with a 6 speed transmission earlier this week and it had the same harsh 2/1 downshift at a stop a few times - so apparently that's not unique to the 8 speeds. The 2018 Silverado loaner I had while mine was in the shop shifted fine, but it has 130 miles on it and was the 5.3 6 speed so it was still learning for sure.

[benelli]

On 8/25/2017 at 2:29 PM, mookdoc6 said:

 

Needs more time....8speeds take forever to settle down.....Flush the Trans it will help immensely too!

LOL really Dude flush the trans. Are you alright. on a brand new truck what makes you think flushing the trans is the problem. if that solved your problem then what you had was the wrong transmission fluid in there. Gm screwed up on previous years and put wrong factory fill in these junk transmissions. This came straight from a Transmission Tech at gm. They had to flush 3 times and fill with Mobile1 HP Trans fliud. A 60,000k truck that need to have the trans flushed within a few thousand miles or right off the bat. thats not a fix thats gm not knowing themselves wtf is going on.

[mookdoc6]

1 hour ago, benelli said:

LOL really Dude flush the trans. Are you alright. on a brand new truck what makes you think flushing the trans is the problem. if that solved your problem then what you had was the wrong transmission fluid in there. Gm screwed up on previous years and put wrong factory fill in these junk transmissions. This came straight from a Transmission Tech at gm. They had to flush 3 times and fill with Mobile1 HP Trans fliud. A 60,000k truck that need to have the trans flushed within a few thousand miles or right off the bat. thats not a fix thats gm not knowing themselves wtf is going on.

Wooo....Dude before you come kicking the door in better have the knowledge first!

 

You have no idea......The problems with the first runs of 8L90's if your even aware of that or M5U RPO code?  The fuid in my Trans was correct HP so GM did not **** that up?  The quantities amount filled and and shredding of soft material buildup  was the main problem....Others had pump issues etc.....

 

Yes, the Truck immediately ran better after the flush so yeah guess I am an idiot along with countless other guys who had early 8l90's and flushed there problems away...Thanks bra for your help!

 

Surging/Flaring gone! never a problem since

Edited November 29, 2017 by mookdoc6

[benelli]

8 hours ago, mookdoc6 said:

Wooo....Dude before you come kicking the door in better have the knowledge first!

 

You have no idea......The problems with the first runs of 8L90's if your even aware of that or M5U RPO code?  The fuid in my Trans was correct HP so GM did not **** that up?  The quantities amount filled and and shredding of soft material buildup  was the main problem....Others had pump issues etc.....

 

Yes, the Truck immediately ran better after the flush so yeah guess I am an idiot along with countless other guys who had early 8l90's and flushed there problems away...Thanks bra for your help!

 

Surging/Flaring gone! never a problem since

No such thing as early or late build on these transmissions or any drive drain components on the trucks. You think the transmissions are any different from one year to the next it’s whatever they have in stock you might have a 2017 or 18 they have the same transmission in in in just a different software program to meet cafe standards. Get a aftermarket tuner men and the shifts patterns work perfect . Lol there not going to tell you they used the wrong trans fluid . That would make them look like fools. Listen I don’t go by the pencil pushers at the service counter. The service guy I had told me to go for a test drive with the transmission tech . When he got in my truck and we left he said these transmissions are junk. Even Escalades over 100 grand have these issues. The service advisor was quick to come over to the truck when the tech and I were talking . So as he could not give me to much info about the issue . Being an independent auto tech myself I believe the front line mechanic working in my truck not the trained service advisors that try to blow smile up peoples *** trying to tell them it’s normal operation. Take this info as you will . Front line service tech open these things up all day long that’s who I believe. 

[mookdoc6]

47 minutes ago, benelli said:

No such thing as early or late build on these transmissions or any drive drain components on the trucks. You think the transmissions are any different from one year to the next it’s whatever they have in stock you might have a 2017 or 18 they have the same transmission in in in just a different software program to meet cafe standards. Get a aftermarket tuner men and the shifts patterns work perfect . Lol there not going to tell you they used the wrong trans fluid . That would make them look like fools. Listen I don’t go by the pencil pushers at the service counter. The service guy I had told me to go for a test drive with the transmission tech . When he got in my truck and we left he said these transmissions are junk. Even Escalades over 100 grand have these issues. The service advisor was quick to come over to the truck when the tech and I were talking . So as he could not give me to much info about the issue . Being an independent auto tech myself I believe the front line mechanic working in my truck not the trained service advisors that try to blow smile up peoples *** trying to tell them it’s normal operation. Take this info as you will . Front line service tech open these things up all day long that’s who I believe. 

 

Ok, I guess my family connection to the Dealership and owner is blowing smoke up my ass?  There is really nothing wrong with the 8L90's other than incorrect fill amounts, soft clutch debris buildup, few pump issues not related to pump but outlet and programming which is what it is.....TCM's mainly good just replaced for nothing so GM had to put an end to it................Yes, obviously a tune will help and negate some GM programmed things but the 8L90 is beast of Transmission and very good thanks for your help!  Knowledgeable too!

[Threerun]

On 5/31/2017 at 11:28 PM, Threerun said:

I'm currently at 12,000 miles since December in my 2016 LTZ 6.2 8spd. Only an occasional clunk or weird lurch, but 99.5% of the time it's smooth as silk. I'm pretty impressed with it..

Well hate to say this, but my 2016 LTZ 6.2L 8spd tranny is at the dealer with an early diagnosis of a transmission failure. I have 34,000 on the ODO. Honestly the transmission when new shifted like butter, and then around 12,500 I started experiencing some hard shifts. Dealer reflashed. Then around 24,000 miles the symptoms re-appeared, they supposedly did the updated re-flash. Took in yesterday at 34,000 miles for routine service, and the transmission was still experiencing hard shifting AND delayed engagement in D or R AND some erratic RPM bounce. It wasn't all the time, but it was noticeable. 

Also my sliding rear window is getting replaced- on the passenger side a soldered electrical something or another (looks like a clip of sorts) fell off. They son't repair- they replace.. 

Man I really love this truck. I've logged 34,000 miles in 18months- so comfortable. Don't know if I can put up with an unreliable transmission. I go to some remote places and it would SUCK to get stranded 50-75+ miles from closest tow facility!

[huntr1117]

I just picked up my 17 from being at the service dept for the 4th time. I'm at 24k miles. Last 3 times it was there they updated to the latest software and did a trans relearn to help with the clunk, hard shifting, and shudder. This time they flushed the trans and updated the software again. Honestly it drives so much better than it ever has now. We'll see how long it lasts but I'm happy with it finally. Is it perfect? No, but it doesn't bother me anymore. If the shudder and clunk come back I'm going with a blackbear tune.

Sent from my SM-G950U using Tapatalk

[BobHancock]

Now at 848 miles on my '18 8 speed it's smooth as butter.  Hope it's OK at 1000 miles. 

 

[Threerun]

On 5/24/2018 at 10:34 AM, Threerun said:

Well hate to say this, but my 2016 LTZ 6.2L 8spd tranny is at the dealer with an early diagnosis of a transmission failure. I have 34,000 on the ODO. Honestly the transmission when new shifted like butter, and then around 12,500 I started experiencing some hard shifts. Dealer reflashed. Then around 24,000 miles the symptoms re-appeared, they supposedly did the updated re-flash. Took in yesterday at 34,000 miles for routine service, and the transmission was still experiencing hard shifting AND delayed engagement in D or R AND some erratic RPM bounce. It wasn't all the time, but it was noticeable. 

Also my sliding rear window is getting replaced- on the passenger side a soldered electrical something or another (looks like a clip of sorts) fell off. They son't repair- they replace.. 

Man I really love this truck. I've logged 34,000 miles in 18months- so comfortable. Don't know if I can put up with an unreliable transmission. I go to some remote places and it would SUCK to get stranded 50-75+ miles from closest tow facility!

Well gotta love this. Wednesday when I took the truck in the Service Mgr said- "we were able to replicate the issues, looks like we'll need to keep the truck and install a new transmission". Thursday afternoon he calls "We did a reflash last night and we were unable to replicate the problem, so you are good to go".

 

Huh? This is the third reflash, and the pesky issue keeps re-occurring. I was like "Hey so yesterday you knew the problem existed and the tech was ready to pull the pin on a new tranny, and now it's all hunky-dory?" I called BS on this. Made him document all this, and I opened a case with GM. We'll see. 

[JacobC1983]

In general are the 2018s better?  Or same stuff just different year?

 

 

 

[Dnt]

On 5/28/2018 at 6:34 AM, JacobC1983 said:

In general are the 2018s better?  Or same stuff just different year?

 

 

 

Would love to know this myself. i typically trade every year and I am looking at maybe a Black truck this time around. This 2017 is pretty good but still has an occasional episode where it has a harsh downshift....... 

[Dr Awesome]

I have almost 2k on my '18 and don't have any issues yet, but I'm going to look into a pre-mature flush/flash at around 10k.  Small price for a little peace of mind, even if it doesn't do anything, I'd only be out a relatively small amount of money.  I've spent more on dumber stuff!  Plus, if there's an upgrade on fluid I'd be all over getting that swapped in.

[Dnt]

Got the 2018 Denali Ultimate last Friday. So far the shifts are crisp and no harshness but I am only at 600 miles. Liking this GM Borla exhaust that I had put on this one before i picked it at the dealer, just has a deep throaty sound. Makes any distress over a harsh downshift insignificant if it happens my plan is to get on the gas Hahahaha