Jump to content

Infamous 8 Speed Transmission Clunk - Dealer/GM Current Position on the Issue?

Abonino
 Share

Recommended Posts

flyingfool Senior Enthusiast

flyingfool

Posted
Posted (edited)
1 hour ago, LunkerHunter said:


Can disabling the TCC system for the first 4-5 gears be accomplished with the Diablo i3?


Sent from my iPhone using Tapatalk

call them and ask... i believe diablo can modify remotly and send you a file to install in the truck with thier tuner., i suggest buying hptuners,  you will have to pay for unlock and the truck credits

Edited by flyingfool
  • Replies 162
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

reardiff
reardiff

Man I need to stop reading these posts. Everything is perfectly fine then once I get on here I swear the next time out my brain insists I have every clunk, bump, shudder and vibration - It's amazing h

amxguy1970
amxguy1970

The consensus is the same in all the other threads you searched, nothing has changed each situation and each dealer response is unique.   Not sure what to tell you but try another dealer? Wh

Abonino
Abonino

Um....   what makes it infamous?    How about the thread on similar GM truck transmission issues that stretches for 25 pages elsehwere on this forum?  How about GM stonewalling both through their deal

Posted Images

sgiangregorio Enthusiast

sgiangregorio

Posted
Posted

My Sierra is at the dealer today for the clunk and shutter. Of course they said they can't reproduce, so they asked to keep it overnight so they could drive it when cold in the morning. That's fine, but since it doesn't do it every time, they may not feel it. I asked if they could just apply the TSB and do the fluid change, but they said they have to be able to reproduce it. The bumper to bumper warranty is up in 1000 miles, would the powertrain warranty still cover me till the 60K if they don't do the fluid before the bumper to bumper is over?

reardiff Enthusiast

reardiff

Posted
Posted (edited)

 

9 hours ago, sgiangregorio said:

I asked if they could just apply the TSB and do the fluid change, but they said they have to be able to reproduce it. 

Not true... Below is the TSB and clearly says diagnosis beyond the customer compliant is not required.  I would print the TSB and bring it with you and show them this then see if they will do it with out being able to reproduce it.  For what it's worth, I had the same clunks, harsh down shifts and then the TCC shudder. Once they did the fluid exchange all of that was gone. So far it's been about six months and no issues, drives like it should finally.  This was done under power train warranty after bumper to bumper had run out. 

 

image.png.fe5b5810ff716cd958c203c6787241a7.png

Edited by reardiff
sgiangregorio Enthusiast

sgiangregorio

Posted
Posted
36 minutes ago, reardiff said:

 

Not true... Below is the TSB and clearly says diagnosis beyond the customer compliant is not required.  I would print the TSB and bring it with you and show them this then see if they will do it with out being able to reproduce it.  For what it's worth, I had the same clunks, harsh down shifts and then the TCC shudder. Once they did the fluid exchange all of that was gone. So far it's been about six months and no issues, drives like it should finally.  This was done under power train warranty after bumper to bumper had run out. 

 

image.png.fe5b5810ff716cd958c203c6787241a7.png

Thanks. I didn’t catch that in the TSB. I would have pushed back today when they said “we don’t just fix things we can’t reproduce.” If he tells me tomorrow the same thing I’ll point him to this. I brought the TSB this morning and he said he didn’t need it, that they would look up TSBs themselves and apply them as required. 

reardiff Enthusiast

reardiff

Posted
Posted (edited)

This is also covered under the 5 year / 60k power train warranty so even once your 3/36 is up you still have coverage should the shutter come back or need a new TC.  Although I will say it was night and day difference on mine, immediate improvement on the clunks and harsh down shifts.  Some say the shutter comes back after a few thousand miles so we'll see, but for now the new fluid certainly was noticeable a improvement.  And you get new fresh fluid exchange at 35k miles for free ; ) 

Edited by reardiff
sgiangregorio Enthusiast

sgiangregorio

Posted
Posted
13 minutes ago, reardiff said:

This is also covered under the 5 year / 60k power train warranty so even once your 3/36 is up you still have coverage should the shutter come back or need a new TC.  Although I will say it was night and day difference on mine, immediate improvement on the clunks and harsh down shifts.  Some say the shutter comes back after a few thousand miles so we'll see, but for now the new fluid certainly was noticeable a improvement.  And you get new fresh fluid exchange at 35k miles for free ; ) 

Thanks. Here’s to hoping I don’t have to get too firm with the service writer to make it happen. 

mcbartell New Member

mcbartell

Posted
Posted

I just purchased my 2017 Sierra Denali from a GM dealer with 61,9XX miles. On the test drive I did not notice the transmission stuttering nor for the first drive one hour home. Through out the next 2 weeks I progressively noticed it more and more. When I finally took a longer drive at highway speeds the stutter was undeniable. Called the dealership and they were very willing to do a transmission flush at no cost to me. 1 Hour later I was back on the road and the truck drives perfect. 

flyingfool Senior Enthusiast

flyingfool

Posted
Posted
7 hours ago, mcbartell said:

I just purchased my 2017 Sierra Denali from a GM dealer with 61,9XX miles. On the test drive I did not notice the transmission stuttering nor for the first drive one hour home. Through out the next 2 weeks I progressively noticed it more and more. When I finally took a longer drive at highway speeds the stutter was undeniable. Called the dealership and they were very willing to do a transmission flush at no cost to me. 1 Hour later I was back on the road and the truck drives perfect. 

they probably installed a software flash to the truck, fluid change wont make a night or day difference in driveability

sgiangregorio Enthusiast

sgiangregorio

Posted
Posted

Just had a nice argument with the service advisor now on their second day with my truck. He said the tech reads all the same stuff I can. I said great, then he knows it doesn’t matter if he feels it or not he should do it. He said the tech is going to drive it for the first time today in a few minutes. I told him I really don’t care if he feels it or not because it’s there and per the TSB they can do it on my word. So he should talk to his service manager and/or call GM but I expect it to be done. Frustrating. 

sgiangregorio Enthusiast

sgiangregorio

Posted
Posted

And just got the follow up call that the tech felt the hard clunk from 1-2 and then again from 2-1, so he's doing the trans fluid change now. :) Also had the rear window recall done, the wireless charger harness replaced, and the console lid replaced (elbow divet) under warranty.

 

sgiangregorio Enthusiast

sgiangregorio

Posted
Posted

And to round this out, what a huge difference in the transmission with the new fluid. Honestly, it's not even like the same truck. Very smooth. Very. If this lasts, I'm a happy camper.

rockusaf Enthusiast

rockusaf

Posted
Posted

I've only had my 2017 for a few months and it has just over 41K miles (it was a lease turn in) and it does clunk at times. Most of the time I notice it is downshifting from 2 to 1 and usually it's when I'm just getting off the gas but I have no idea if it has ever had the fluid changed, is there a way to check before I take it to the dealer?

 

Rock

JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted
1 hour ago, rockusaf said:

I've only had my 2017 for a few months and it has just over 41K miles (it was a lease turn in) and it does clunk at times. Most of the time I notice it is downshifting from 2 to 1 and usually it's when I'm just getting off the gas but I have no idea if it has ever had the fluid changed, is there a way to check before I take it to the dealer?

 

Rock

If were a lease, there should be pretty detailed service records from the person who had it before at the dealership it was leased from (hopefully).

 

If the fluid was changed under the TSB (warranty), your VIN should reflect that if checked.

dgstarr63 Enthusiast

dgstarr63

Posted
Posted

My 2021 5.3  8 speed has started to clunk when slowing to a stop light. It was perfect until 1200 miles. My dealer told me that they had not seen any 8 speed issues since the 2019 models. I haven't taken it in yet. Has anyone else had problems with the newer truck 8 speeds?

flyingfool Senior Enthusiast

flyingfool

Posted
Posted
17 hours ago, dgstarr63 said:

My 2021 5.3  8 speed has started to clunk when slowing to a stop light. It was perfect until 1200 miles. My dealer told me that they had not seen any 8 speed issues since the 2019 models. I haven't taken it in yet. Has anyone else had problems with the newer truck 8 speeds?

try using manual gear mode, select the best gear for the situation. dont use the last gear as this usually activates DoD and might contribute to hesitation, and clunks,  so 8spd drive in 7th gear and feel it out

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,913
    Total Members
    8,960
    Most Online
    Smitty462
    Newest Member
    Smitty462
    Joined

  • Who's Online   3 Members, 1 Anonymous, 638 Guests (See full list)

  • Latest Articles

  • Posts

    • Grumpy Bear
      Some Assembly is Required

      By Grumpy Bear · Posted

      Can it still be Assembled I?    Stribeck says that we need a certain amount of viscosity under conditions of load and velocity to prevent two surfaces of a know roughness from tearing each other asunder. And we have marketing trying to tell the masses that those two surfaced require less of that commodity due to more exact limits being placed on the same old clearances. We also know that there are limits to how hard something can before it becomes to brittle to be viable and to smooth to 'wet' the surface and that both of those conditions have been known and met since about the Second World War.    That viscosity value shook out at 10 centistokes at 212 F just under a hundred years ago.  Give this a look: [Anton Parr]     What is advertised is the Kinematic viscosity (mm2/s) or that which has been density adjusted but the value we are after is the dynamic viscosity (mPa.s) or true viscosity. You can see that this number is dependent on density thus base stock and temperature. You can also see that an SAE 30 doesn't reach that value in this example. However an SAE 30 that is at the upper end of the SAE 30 range; 12.5 cSt (mm2/s), might. 12.5 * .83 = 10.375 (mm2/s). If you could find an SAE 30 at the upper end these days.   Then there is the complication of viscosity modifiers or VII or VM, whatever you wish to call them. Polymers added to very thin base oils, perhaps 3 to 6 cP oils, that will meet the SAE *W30 spec at 'tested' shear rates and 100 C/212F  target temperature. So a polymer fortified base that is a fraction of the 10 cP requirement Stribeck insist upon.   This could be all well and good if those polymers didn't have two very problematic 'features'. They shear or loose viscosity both 1.) permanently and 2.) temporality. And they do both omitted in the advertised data with the distinct  purpose of deceiving the consumer of the actual operating state of the fluid. I've shown the example of Warren Oils COSTCO 10.91 cSt 5W30 formuation several times where the 100 C HTHS value is 6.9 cP!! That's the temporary shear down and with and SSI or shear stability index of 9.4 cSt. Note the intentional deception in using mixed units?    After a short while that 9.4 cSt oil has a viscosity corrected dynamic value of 7.8 cP. But as the SSI is still within the range of an SAE *W30 whose lower value is 9.3 cSt.    This allows them to continue to call this SAE 16 weight oil a 30 weight, the cake, and still meet the API requirements for fuel efficiency IMPROVEMENT mandated by the EPA. The eating of the cake. By the time you've worn out your motor doing the responsible thing by adhering to the warranty requirements, (the stick), you get deprived of the carrot, wear control. So sad, to bad.   So what can be done? Do I need actually say? [Anton Parr]       Even this must be monitored if the oil is on the low side and the VII an organic or you opt for a 0W40 with an even lighter base oil and more / higher MW VII. (Note the lower density of the 40 weight versus the SAE 30 mono-weight?)    There is another workaround. Temperature. An SAE *W30 run at a bulk temperature of between 180 and 195 F.    Being the belt and suspenders sort I am I do both. Run it cook and run it heavy.    In Part II I'll work the AW package. 
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      So, do I go elbow-deep on this thing or list it for sale and play dumb? Seems to "runs good."   I'm about $1200 away from having: -a rebuilt injector ($300) -a new cat ($250) -a new cat back exhaust (OE style) ($300) -a new AC compressor ($200) -AC refrigerant charge ($150)   In theory, this should rectify the obvious detracting issues from its value and operability. Cold AC with a non-squeaking AC pulley both sounds and feels good. An exhaust that isn't cut/hacked in 17 different places and doesn't vibrate on a crossmember would make it sound and feel less janky. A working cat would help the stink, and will save the earth, but *if and only if* the fuel system is working properly, which would also address the intermittent "rich" CEL.   Heard a good one... CEL for "Rich condition" means you haven't spent enough money on the truck lately, and it's letting you know.   Rebuilding the injector would seem to be the most important part. Replacing the cat would be secondary. I don't think mine is plugged or overly restricted, but it might be a little restricted? I have no good way to tell other than seat of the pants feel. I hate the smell.   The current theory is I have a rich idle problem: A bad fuel pressure regulator, or a leaking injector(s) being the highest probabilities. I already replaced the FPR but that doesn't mean its replacement isn't also bad. It was a new part from Dorman, but the packaging looked like it had been sitting on a shelf for 20 years.   This is the (single) upstream O2 sensor shown at idle. I'm getting a lot of "rich" it seems. Sometimes it stays high like that and doesn't drop down. That makes me think it's processing injector leaks or a partially stuck open injector.     Other times it looks like this. Nice oscillations between rich and lean, which is what I think it should be. Under load and at speed, the oscillations are nice and tight and uniform looking, high and low.     Fuel trims suggest the PCM is compensating pretty hard at idle to pull fuel out. But it's not enough to trip a CEL. Something about slowing to a stop: brake vaccum booster, EGR, or the EVAP purge is delayed, or there's pooled fuel in the intake again that's draining into a cylinder is enough to set the CEL. Of course, in two days of driving, it hasn't set. I was hoping to actually look at the freeze-frame data when it sets. IAT is high because it's idling on an 83 degree day here.  
    • Another JR
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By Another JR · Posted

      Have considered installing a DC to DC charger in your camper to replace your isolator?  
    • newdude
      Gas fill door

      By newdude · Posted

      Common failure.  You need to replace the fuel door housing.   The painted cover transfers over to the new housing.  To remove the old one there is 4 spots where you poke the plastic to release it.  
    • newdude
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By newdude · Posted

      No such thing as regenerative braking on a pure ICE vehicle.     Regenerative braking is the re-capture of energy from electric motors and stores it in the battery pack.  So hybrids, PHEV and EVs have regenerative braking.     What you are seeing is the charging system changing modes is all.  Its likely entering charge mode for some sort of reason is all.  All of the charging modes will be listed below.   As for L10 vs D.  L10 turns off automatic grade braking.  L10 puts you in control of grade downshifts where in D it will automatically do it based on brake pedal position and other factors.  Otherwise L10 and D drive exactly the same aside from that one aspect.    Battery Sulfation Mode The BCM will enter this mode when the interpreted Generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2–3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.   Charge Mode The BCM will enter Charge Mode when ever one of the following conditions are met:   Windshield wipers are ON for more than 3 s. Climate Control Voltage Boost Mode Request is true, as sensed by the HVAC control module via serial data. High speed cooling fan, rear defogger, and HVAC high speed blower operation can cause the BCM to enter the Charge Mode. The estimated battery temperature is less than 0°C (32°F). Battery State of Charge is less than 80%. Vehicle speed is greater than 145 km/h (90 mph) A current sensor malfunction exists. System voltage is determined to be below 12.56 V When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 V, depending on the battery state of charge and estimated battery temperature.   Fuel Economy Mode The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 A and greater than −8 A, and the battery state-of-charge is greater than or equal to 80%. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5–13.1 V. When fuel economy mode is active, the generator is not charging, only maintaining open circuit battery voltage. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.   Headlamp Mode The BCM will enter Headlamp Mode when ever the head lamps are ON (high or low beams). Voltage will be regulated between 13.9–14.5 V.   Start Up Mode When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 s.   Tow/Haul Mode (if applicable) Pressing the Tow/Haul Mode button located on the center stack, the vehicle system voltage is raised and the remote (non-vehicle) battery will be charged. Having the headlamps on will raise the system voltage and if the Tow/Haul button is applied it will not serve any purpose. The voltage is regulated between 13.9-14.5 V.      

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...