Jump to content

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

Abonino
 Share

Recommended Posts

reardiff Enthusiast

reardiff

Posted
Posted

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 how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)

 

  • Like 2
  • Haha 1
  • 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

TXGREEK Senior Enthusiast

TXGREEK

Posted
Posted
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 how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)   

 

 I’ve found myself contemplating the same. Every time I call my favorite off-road shop, the techs say “ oh no, what did you hear this time?” Lol. Think about it, if every time you get into a new vehicle then read some of these forums then you’ll start making excuses for every little sound you hear...WAIT....SHhhh! Did you hear that??? I think my truck is about to EXPLODE!!!!

 

 

Sent from above

 

 

  • Haha 1
SkiDooNick700 Enthusiast

SkiDooNick700

Posted
Posted

The worst part is I use my dads '17 Ram 2500HD 6.4L when my truck is getting serviced.  So much for that horrible reliability... does better than my truck lol!!

benelli Enthusiast

benelli

Posted
Posted (edited)
16 hours ago, reardiff said:

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 how you can not notice anything and think you have the best truck ever, then all then after reading all the stories on here just know you have a lemon ;)

 

Lol welcome to the club. All you guys forget about what the service advisors tell you. There all former mechanics that haven’t been under a hood I’m years. Dealerships bump them up to service advisors so they can upsale services most probably don’t need. Your transmission and hard shifting will never go away regardless of how many re-learns and trans flushes they do. It’s a bad designed transmission . They won’t put out a recall as it’s not a safety issue they will just keep stinging you along with let’s try this let’s try that. In the end they will tell you it’s normal operation. You really think the tech is talking to gm tech support about a fix for your transmission there trying to get confirmation if they can change out the entire transmission for a new one which is no better it will string along for awhile and do the same thing . It’s not that your trans is a defective one. There all defective (bad design) . So you would be getting the same crap installed and the dealer makes more money off of warranty. That’s all.

Edited by benelli
  • Like 1
SkiDooNick700 Enthusiast

SkiDooNick700

Posted
Posted (edited)

Just got a call from my Service guy, said that this Valve Body part is on back order, so I'll pick up the truck today and  he'll call me when the part is in.

 

I asked him if they did the flush, they did not.  I guess they determined the Flush would not resolve my issue.

 

So I guess no further updates from me until whenever this Valve Body part comes in.

 

 

UPDATE- looks like another guy has the same issue as me but he's on vacation for the next several days so I am getting the in stock Valve Body that was supposed to go to him.

Should be ready for pickup tomorrow.

Edited by SkiDooNick700
SkiDooNick700 Enthusiast

SkiDooNick700

Posted
Posted

Hey all, wanted to give an update.

 

Picked truck up on Friday, have since driven it around 20 miles.  Shifts noticeably better!  Haven't had it slam into reverse or drive.  Also I had delayed engagement before, however on the few cold starts I've done, it shifts pretty much almost right away into Reverse/Drive with no clunks/noise.  As it shifts thru the gears, its pretty smooth now.  The 3-4 and 4-5 shifts ( I think) sometimes have a slight firmness to them where to feel it switch.  Otherwise, its been smooth.  I'm much happier now.  Will see how this week goes with driving it to work and back every day. Also, the shudder is gone and the tach doesn't flutter like it used to when in a higher gear between 1000 - 1500 rpm and holding a steady speed.

 

So here is what they did:

Replace Valve Body - mine had a damaged bore

Put in 8 quarts of the new trans fluid released by GM (they did not do a full flush)

 

"TEST DROVE VEHICLE, TRANS HAD HARSH 1-2 -2-4 SHIFT 3-1 DOWNSHIFT, INSPECT FLUID LOOKED OK. PERFORMED CIRCUIT TEST WITH GDS, SOLENOID PERFORMED WHEN COMMANDED, STILL HARD SHIFT. REMOVED VALVE BODY FOR INSPECTION FOUND VALVE BODY FAULTY BORE HAD DAMAGE. REPLACED VALVE BODY, PERFORMED CHARACTORIZATION ON VALVE BODY"

 

 

This is another reminder to myself that being patient and waiting til powertrain warranty expires in May 2020 is worth the wait.  Between this trans issue and the lifter/pushrod work that had to be done, it's been completely painless to work with the dealership :-)

  • Like 1
Euriel94 New Member

Euriel94

Posted
Posted

Took in my 2015 Denali that had shuddering issues on steady speeds of 30-70mph to my gmc dealer they replaced the transmission fluid free of charge and feels brand new again ?

drumsbh Enthusiast

drumsbh

Posted
Posted

Took my 2016 GMC Sierra 5.3, 8speed in to have the TSB performed. Paid out of pocket since I'm past warranty.
No more shudder! Cost me $370.

Sent from my LG-LS993 using Tapatalk

tyler.frost92 Enthusiast

tyler.frost92

Posted
Posted
On 3/12/2019 at 9:59 PM, JCKustoms said:

Had mine flushed this morning. It was covered under warranty even though I don’t have the “shudder”.

Have only driven 100 miles, but seems to shift a bit smoother... time will tell. emoji1695.png


Sent from my iPhone using Tapatalk

How did you convince them to do it without having the shudder? I have the occasional harsh downshift and upshift and delayed engagement. Id like to see if the new fluid helps.

JCKustoms Enthusiast

JCKustoms

Posted
Posted
How did you convince them to do it without having the shudder? I have the occasional harsh downshift and upshift and delayed engagement. Id like to see if the new fluid helps.



I made an appointment from the app. Wrote what issues I was having and suggested they perform the TSB for the “shudder”. I had to wait about 3 weeks because they didn’t have the correct tool to perform the flush, although they did have the fluid.

When I went in to drop it off, they didn’t even drive it. They just asked about the symptoms again and then I picked it up 2 hours later. All covered 100% (my truck had 8,400 miles at time of service).

By the way, the fluid didn’t help at all...


Sent from my iPhone using Tapatalk
  • 2 weeks later...
benelli Enthusiast

benelli

Posted
Posted
On 4/2/2019 at 11:29 AM, JCKustoms said:

 

 


I made an appointment from the app. Wrote what issues I was having and suggested they perform the TSB for the “shudder”. I had to wait about 3 weeks because they didn’t have the correct tool to perform the flush, although they did have the fluid.

When I went in to drop it off, they didn’t even drive it. They just asked about the symptoms again and then I picked it up 2 hours later. All covered 100% (my truck had 8,400 miles at time of service).

By the way, the fluid didn’t help at all...


Sent from my iPhone using Tapatalk

If you don`t mind me asking what exactly did you write in the symptoms.

JCKustoms Enthusiast

JCKustoms

Posted
Posted
If you don`t mind me asking what exactly did you write in the symptoms.



I wrote that the trans was experiencing some hard shifts from second to first and first to second. I also wrote that it was very clunky when pressing or depressing the accelerator pedal at speeds above 15mph. And that the trans was clunky when shifting out of park, between gears, and back into park.

I then mentioned if they would perform the fluid flush TSB. And they did. And it didn’t help at all.


Sent from my iPhone using Tapatalk
SkiDooNick700 Enthusiast

SkiDooNick700

Posted
Posted
5 hours ago, JCKustoms said:

 

 


I wrote that the trans was experiencing some hard shifts from second to first and first to second. I also wrote that it was very clunky when pressing or depressing the accelerator pedal at speeds above 15mph. And that the trans was clunky when shifting out of park, between gears, and back into park.

I then mentioned if they would perform the fluid flush TSB. And they did. And it didn’t help at all.


Sent from my iPhone using Tapatalk

 

 

I wonder if your valve body is damaged like mine was.

  • 2 weeks later...
jqcitizen Enthusiast

jqcitizen

Posted
Posted

Having the same issues as the rest of you. Mine has been at the dealership for the last few days.  Problems started around 7000 miles. Hard shift up, and downshifting, shuttering above 30 mph.

Dealer already performed the triple fluid flush. Worked for about 800 miles, then the problem started again.  Nothing worse than doing 60 and feeling like someone has run into your rear end.

 

Looking like its time for a new valve body and possible torque converter.  And the icing on the cake is the rear end vibration.  Trying to see if it is the driveshaft or rear axle.

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

  • 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...