Is it really that bad?

Mandalorian · October 27, 2019

As a general rule of thumb, the first model year of any new generation of vehicle is going to be more prone to issues than later years. Doesn't matter the make/model.

Texas Daddy · October 27, 2019

As a general rule of thumb, the first model year of any new generation of vehicle is going to be more prone to issues than later years. Doesn't matter the make/model.

Yep, but if i HAD to buy a first year run, a later build would be the choice. Those 1st few months on assembly line expose a lot shit (ello rear window seal)...

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bass mechanic · October 27, 2019

having the same issues with the 8 speed in my 2017 Cadillac CTS-V goes in next week for the flush.

my 2017 SIERRA 6.2 has been trouble free but i am thinking about having it checked to see if a flush will help the 1-2 shifts. truck has 19k on it

Thomcat · October 27, 2019

On 10/23/2019 at 7:23 PM, OnTheReel said:

The ZF 8 speed is in just about everything. I’d argue it’s faired a lot better than GM’s 8 speed...no class action suit against it at least.

The IBC system is going to be in everything eventually. Better packaging, faster response in automated emergency stops, no problematic vacuum pump (subject to a recall on the “bulletproof“ K2s as we speak). There’s been growing pains, the T1 is the first vehicle to have it. Nothing wrong with taking a wait and see approach but I wouldn’t condemn it outright. Clearly GM has some confidence in the system or they wouldn’t be risking it in their cash cow.

I know it’s already been shaken out, but the 2019 L82 (AFM) and L84 (DFM) have more in common with each other than they do with the outgoing L83, hence the new RPO code. Wouldn’t consider the AFM motor a carryover.

.02 AFM engines may very well be a short lived carryover. Really big mechanical difference between the leftover L82 AFM "V" designs and the new L84 DFM design. The 19 AFMs cylinder deactivation operates just like the previous 07+ year AFMs with a LOMA lifter manifold controlling deactivation of AFM lifters on 4 cylinders and dumping excess oil into the sump (this AFM discharge valve is what caused oil burning problems on pre 1/11 AFMs until they installed a baffle directing all discharge downward- a long story). The 19+ DFMs eliminate the LOMA manifold in the "V" engine valleys in favor of 8 separate oil control valves directly in the engine block controlling deactivation of all DFM lifters on all 8 cylinders. DFM essentially simplifies the engine by ridding electro-mechanical LOMA and oil discharge valve Achilles heels and substituting direct solenoid control shifting switching the mechanical burden to more complex electronic ECU control.

I could feel the AFM switching on my 07,11,12 and 16 5.3s didn't need to look at the graphic; I can't tell what the DFM is doing because I can't feel any switching and really don't care - maybe that's why there is no graphic display for active cylinders in the DFMs. Some of the low end power it may be due to the 8 speed gearing, but the engine has more power and is smoother running

Thomcat · October 27, 2019

56 minutes ago, bass mechanic said:

having the same issues with the 8 speed in my 2017 Cadillac CTS-V goes in next week for the flush.

my 2017 SIERRA 6.2 has been trouble free but i am thinking about having it checked to see if a flush will help the 1-2 shifts. truck has 19k on it

I wouldn't hold my breath waiting for a flush to correct a hard 1-2 shift. My post 3/19 MQE 8 spd. tranny came equipped with the new Mobil 1 HD juice and I will get a cold hard 1-2 shift.

Got time on my hands with too much thinking and little to go on. Here's my .02 take on it for what it is worth - hard shift has nothing to do with the fluid but their tranny designs for start-stop systems, and it doesn't matter whether it is active, switched off or defeated entirely with an aftermarket gizmo. All trannys operate on hydraulic pressure supplied by and engine driven internal mechanical pump, engine stops no hydraulic pressure. No hydraulic pressure to the band servos which brake and release planetary drums for different gear combos and no drive or wrong gears applied. So to keep pressure applied to the servos and other hydraulic controls in the tranny, the mechanical pump does not directly feed the servos but feeds pressure into what they call an accumulator that keeps pressure applied to the first speed gearset so you can get immediate gear application from an auto stop. Without pressure from the accumulator, it will take time for the pump to fill the accumulator before the band can be applied. I'm guessing that the accumulator will maintain pressure during a drive cycle and for short periods of time after parking. But on a long park, overnight cold etc. the pressure in the accumulator bleeds and needs a refill before it can engage first gear........thus you'll get a delay and then a slam into gear when pressure forces the band onto the drum for first gear engagement. Might be something to this tried a cold start shifting through all the gears including "L" for a second or two before hitting reverse out the driveway and didn't bang into first and slow slower acceleration actually gave me a 1-2 shift which was softer, but with solid no engine flaring engagement. If this is the case, it is doubtful that any software update will correct since no safe way to speed up accumulator refill using an engine speed driven mechanical pump.

https://gm-techlink.com/?p=11127

Can't find my crossection of the 8 speed tranny that shows the physical location of accumulator but its necessary existence in s/s is mentioned in this article for my 9 spd Traverse tranny. The 9T50 transmission also supports auto engine stop/start operation. "A unique accumulator within the transmission allows for refined stop/start transitions. The accumulator stores energy for engine restarts, while the software is calibrated for those smooth restarts." BTW my 9 speed Tranny doesn't share this problem, even running on the old Dextron because to create a compact design for FWD application it doesn't use the accumulator or hydraulic servo for first gear engagement from an autostop or overnight cold but a one way mechanical Sprage clutch and modified tc for instant engagement.

Thomcat · October 27, 2019

AFM vs. DFM

https://gm-techlink.com/?p=11880

bass mechanic · October 27, 2019

I wouldn't hold my breath waiting for a flush to correct a hard 1-2 shift. My post 3/19 MQE 8 spd. tranny came equipped with the new Mobil 1 HD juice and I will get a cold hard 1-2 shift.

Got time on my hands with too much thinking and little to go on. Here's my .02 take on it for what it is worth - hard shift has nothing to do with the fluid but their tranny designs for start-stop systems, and it doesn't matter whether it is active, switched off or defeated entirely with an aftermarket gizmo. All trannys operate on hydraulic pressure supplied by and engine driven internal mechanical pump, engine stops no hydraulic pressure. No hydraulic pressure to the band servos which brake and release planetary drums for different gear combos and no drive or wrong gears applied. So to keep pressure applied to the servos and other hydraulic controls in the tranny, the mechanical pump does not directly feed the servos but feeds pressure into what they call an accumulator that keeps pressure applied to the first speed gearset so you can get immediate gear application from an auto stop. Without pressure from the accumulator, it will take time for the pump to fill the accumulator before the band can be applied. I'm guessing that the accumulator will maintain pressure during a drive cycle and for short periods of time after parking. But on a long park, overnight cold etc. the pressure in the accumulator bleeds and needs a refill before it can engage first gear........thus you'll get a delay and then a slam into gear when pressure forces the band onto the drum for first gear engagement. Might be something to this tried a cold start shifting through all the gears including "L" for a second or two before hitting reverse out the driveway and didn't bang into first and slow slower acceleration actually gave me a 1-2 shift which was softer, but with solid no engine flaring engagement. If this is the case, it is doubtful that any software update will correct since no safe way to speed up accumulator refill using an engine speed driven mechanical pump.

https://gm-techlink.com/?p=11127

Can't find my crossection of the 8 speed tranny that shows the physical location of accumulator but its necessary existence in s/s is mentioned in this article for my 9 spd Traverse tranny. The 9T50 transmission also supports auto engine stop/start operation. "A unique accumulator within the transmission allows for refined stop/start transitions. The accumulator stores energy for engine restarts, while the software is calibrated for those smooth restarts." BTW my 9 speed Tranny doesn't share this problem, even running on the old Dextron because to create a compact design for FWD application it doesn't use the accumulator or hydraulic servo for first gear engagement from an autostop or overnight cold but a one way mechanical Sprage clutch and modified tc for instant engagement.

Both my vehicles mentioned don’t have start/stop on them. Lots of folks complaining of the shudder issue totally unrelated to what your talking about. The fluid fixes all the cases I’ve seen. As for the 1-2 and 2-1 shifts my 2015 was worlds different after a software update to the TCM.
Also found that after my valve body replacement in my CTS-V drove like new. So that blows your theory of accumulator and clutches all to pieces.
Personally I think the issue with the 8 speed has more to do with clutch timing engagement/disengagement combined with the viscosity of the fluid which varies based on temp and if the fluid is not holding up due to water contamination or other variables that the trans was never designed to compensate for.
Now that they are up to 10 speeds transmissions are becoming a lot more like a CVT and the gear ratios are so close to each other the transmission doesn’t have to slip much between shifts and a lot less wear on clutches since each is used so little.
Needless to say things have gotten a lot more complex.
I can tell you my 10 speed Allison (GM designed to their specifications) has been flawless. I believe the 10 speed in the half ton trucks is co-developed with ford and GM so if that trans has issues it will affect a lot more than just GM vehicles. Therefor will get a lot more attention

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Doolin-Dalton · October 28, 2019

Not bad at all. I haven't had any problems with my truck.

SILVER SLED · October 28, 2019

At the little GM dealership I work at I have never seen a K2 or any truck bought back for that matter. I have seen one T1 bought back so far.

Edited October 28, 2019 by SILVER SLED

Thomcat · October 28, 2019

12 hours ago, bass mechanic said:

Both my vehicles mentioned don’t have start/stop on them. Lots of folks complaining of the shudder issue totally unrelated to what your talking about. The fluid fixes all the cases I’ve seen. As for the 1-2 and 2-1 shifts my 2015 was worlds different after a software update to the TCM.
Also found that after my valve body replacement in my CTS-V drove like new. So that blows your theory of accumulator and clutches all to pieces.
Personally I think the issue with the 8 speed has more to do with clutch timing engagement/disengagement combined with the viscosity of the fluid which varies based on temp and if the fluid is not holding up due to water contamination or other variables that the trans was never designed to compensate for.
Now that they are up to 10 speeds transmissions are becoming a lot more like a CVT and the gear ratios are so close to each other the transmission doesn’t have to slip much between shifts and a lot less wear on clutches since each is used so little.
Needless to say things have gotten a lot more complex.
I can tell you my 10 speed Allison (GM designed to their specifications) has been flawless. I believe the 10 speed in the half ton trucks is co-developed with ford and GM so if that trans has issues it will affect a lot more than just GM vehicles. Therefor will get a lot more attention

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It's really irrelevant what trannys you have in your older vehicles lacking start stop compared to '19 T1 8 speeds on s/s vehciles. It's comparing apples to oranges.....they're ancient history ........you're posting on the T1 forum and my post specifically addresses a new redesigned 8 speed tranny redesigned for T1 8 speeds with s/s operation. Old tech trannys do not contain a pressure accumulator because their engines do not autostop and engines are constantly turning the mechanical tranny pump for pressure. This is the '19+ section for T1's and I'm referring to the 8 speeds designed for start-stop.....different tranny...... different problem. My post addressed the ONLY first cold hard 1-2 shift as associated with s/s, and possible long sit/overnight bleed down of accumulator pressure and swapping out the old hydroscopic fluid for new stuff may make for smoother shifting but will have no affect on accumulator refill rate after a pressure bleed down over time. Those old 8 speeds without s/s have no need for the accumulator so they do not have one their shifting problems are different than the hard 1-2 shift when cold....wrong forum for posting.

Edited October 28, 2019 by Thomcat

KARNUT · October 28, 2019

Ah, another fuel savings GM screw up.

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RE1 · October 28, 2019

On 10/23/2019 at 10:13 PM, flyingfool said:

ZF is in Chrysler, Dodge, Range rover Hondas, maybe Mercedes . the low end models with lots of gears are a disaster. anything 8-9 speed is trash and they knowingly sell junk, you wont see ZF do recalls cause they just put a brand new POS tranny in and send you on your way. hoping it holds together til' warrantee is up. the worste software programming for transmissions, so I would be very leary of thier brake designs, shit aint even made by our engineers its all from Europe and germany. screw driving a T1 truck

The actual ZF transmissions built by ZF in Germany are outstanding.

Mandalorian · October 28, 2019

27 minutes ago, RE1 said:

The actual ZF transmissions built by ZF in Germany are outstanding.

The ZF 8-speed is one of the best transmissions on the market, if not the best.

SILVER SLED · October 28, 2019

I love my 8 speed. Not one issue and it shifts and drives great. I drove a 19 with a 5.3 with an 8 speed for a weekend and it also shifted and drove great. I wonder if the early 8 speeds had programming issues and the new advanced, expensive to tune 8 speeds transmission control modules fixed a lot of that. Of course that wont fix a torque converter shutter issue.

Belo · October 28, 2019

generally people don't come onto a forum or take a survey to waste time and say "today my drive to work was just fine". But they do come on to post their issues. So it can seem like the truck is full of problems, when it's not. No truck is trouble free.