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  • 2 weeks later...
Posted

First of all, thanks for this forum. I experienced this with my 2018 GMC  Sierra Denali. Seemed to be the worse between 60-70 mph, with a slight acceleration. I have felt the vibration throughout the truck. I will have to take the truck in as soon as I get a chance.

  • 1 month later...
Posted

Hello guys, I know this is an older thread, but I’m having a very similar problem with my 2016 Sierra 1500 6spd, 5.3L. 54,000 miles. At first I thought it was a suspension issue, as it really exactly like I’m driving over rumble strips on the highway, and I also see the tachometer slightly wandering and down while cruising. The problem only occurred while accelerating, which also makes suspension issues less likely. Based on what I’m seeing, the Torque converter or Transmission fluid appears to be the cause of this. Does anyone have any advice on how to approach the dealership with this, so I don’t get the “could not duplicate” response? I drive the car everyday so it’s easy for me to notice it, however a tech will be in the truck for 10-20 minutes, likely low trans fluid temps and I won’t be there to make sure they “witness” it. I appreciate the help. 

  • 1 year later...
Posted

Hello i have this problem just bought a 2018 today and it feels like i have a shimmy only when i accelurate.  I do have alil warranty. Any ideas what i shouod ask them to do ? 

Posted

Just call your dealer service department and they’ll know exactly what your issue is and they’ll change the tranny fluid.  I just had my 2018 Denali with the 6.2 and 8 speed get a complete tranny fluid flush and change.  I have 28000 miles on the truck and noticed the issue arising around 20k.  I bought an AFM delete by Range and that seemed to help the problem between V4-V8 mode for a while and it progressed to get worse.  I too had the rumble feeling primarily through the steering wheel and it also felt like the truck was not running smooth even on new pavement.  I would say that the tranny fluid made all the difference and solved the issue with an exception.  When I initially drove it off the dealer lot I did not plug in my AFM Range delete and got on the highway the rumbling still came into play in V4 mode.  I was pissed.  But then I pulled over and plugged in the Range.  Problem solved so far.  It’s running perfectly with smooth shifting, no clunking, no vibrations.  I think the problem is a combination of the old tranny fluid and made worse by the V4 mode.  Invest in a Range, sucks that you have to pay another $200 to get rid of the issue but V4 mode sucks anyway.  And I did not notice any difference at all in fuel mileage running full time V8.

  • 5 months later...
Posted

2018 Chevy Silverado 6.2L; experienced shutter around 40k miles; transmission flushed/fluid replaced at dealer per service bulletin.  At 62k miles shutter began again; scheduled GM appointment  for 1/31/2022.....hope the issue can be properly diagnosed and repaired.....although now that my 60k mile warranty is expired I am confident it will be an expensive repair.

Posted
1 hour ago, Fun times said:

2018 Chevy Silverado 6.2L; experienced shutter around 40k miles; transmission flushed/fluid replaced at dealer per service bulletin.  At 62k miles shutter began again; scheduled GM appointment  for 1/31/2022.....hope the issue can be properly diagnosed and repaired.....although now that my 60k mile warranty is expired I am confident it will be an expensive repair.

Welcome to the site.

 

Check to see what fluid was used on the first flush. There is a new Mobil 1 Blue Label that is being used now, that replaced the Black Label originally introduced in 2019. 

Posted
On 1/12/2022 at 9:24 AM, Fun times said:

2018 Chevy Silverado 6.2L; experienced shutter around 40k miles; transmission flushed/fluid replaced at dealer per service bulletin.  At 62k miles shutter began again; scheduled GM appointment  for 1/31/2022.....hope the issue can be properly diagnosed and repaired.....although now that my 60k mile warranty is expired I am confident it will be an expensive repair.

Let Us know what happens....

Posted
1 hour ago, MarkJohnson said:

Doesn't GM have their own fluid, a dexron HP something.......

That is what is being replaced in the 8 speeds with the new Mobil 1 Blue Label. 

Posted

Cool- blue label all the way. I'm looking right now at an 18, 8 speed currently have 16, 6 speed. Thru all the reding I've done the blue fluid flush and tuning are the remedies. I've looked at the tune files from earlier and later(18) trucks and some tables have been added such as torque converter slip which is where I've been able to produce TC shedder on my 6L80. Great threat, I've learned alot reading it.........

  • Like 1
Posted

I have a 2018 redline double cab with 5.3 and 6 speed and 20" wheels.  I have dropped my trans fluid 3 times over the course of ownership.  I am now at 79k and owned the truck since new.  There was clunk when i took it home...  but it was never any shaky stuff.

 

I had some shake and shimmy of the center console and rear for a little bit.  I took truck to an old school wheel shop and the older man balanced all 4 the right way.  I can go to 90mph+ and have a smooth ride. 

 

I did the transmission thermostat delete, run fresh fluid every 30k miles... I swapped the pan with one with a drain.  My plan is to change filter every other fluid change.  at this point, i would think my fluid is very new.  At 35k, it was a little brown.  I am now also changing my oil at 5k miles max.  Just too dark at 30% life.  

Posted

Hi all, I recently picked up a 17 Sierra 6.2 and am experiencing the shudder issue as well. The truck has 61,000 on it and actually had the trans flush done in Oct 2019 at around 37,000. I am looking at having it flushed again and am wondering what the P/N is for the blue label Mobil 1 (Dexron-VI?) as P/N 9417577 is what they used before. I can't seem to track down this down.. I do also have the Range afm disabler on it but it doesn't seem to make much of a difference. 

  • 4 months later...
Posted

I have an 8 speed transmission with the shuddering issue (6.2L engine). It has gotten worse after the initial flush from my local dealer. I somehow got them to agree to do it again. Will this cause more harm then good? I believe it has been 2 months or so since the last one. Can anyone give me any advice...I rather not complete destroy it...Thanks!

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