Vibration while driving '20 Silverado

[tcurlee]

I have a "20 Silverado 5.2 It has a very fine vibration while driving at about 43 or so mph that I feel in the seat, not in the wheel. Noticeable with very light acceleration. Any idea what it might be or has anyone had the same issue ?

 

[Mooseman]

Is this with the infamous 8 speed tranny? If so, it has multiple issues and lawsuits to go with them. Shuddering is one of those issues.

 

[tcurlee]

Is this with the infamous 8 speed tranny? If so, it has multiple issues and lawsuits to go with them. Shuddering is one of those issues.

Thanks Mooseman, this may be a dumb question but how do I determine if its an 8 speed ? What other type of automatic is there ?? If it is one of those crazy 8 speeds, what recourse is there ?

 

[Mooseman]

I don't know what the RPO code would be (and I don't think there is even an RPO sticker anymore). You could try putting your VIN in online VIN decoders as some do list the transmission. Or you could just drive it and manually shift it through the gears and see how high it goes.

 

[tcurlee]

I don't know what the RPO code would be (and I don't think there is even an RPO sticker anymore). You could try putting your VIN in online VIN decoders as some do list the transmission. Or you could just drive it and manually shift it through the gears and see how high it goes.

Yes Mooseman, it is an 8-speed trans. It's so much a 'shuddering' as a really fine vibration I feel in the seat in the low 40's mph. Is this something I should take it into the dealership for as it's still under extended warrentee ?

 

[Mooseman]

Yes, I would. They might try to pass it off as normal but it's not. What you're describing sounds like the torque converter clutch. What you could try first is Lubegard's Instant Shudder Fixx. Can't hurt and undetectable if you take it to the dealer.

 

[mrrsm]

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[Mooseman]

I just watched over the weekend a video which is similar to your issue. Maybe the same thing with your driveshaft?

 

[tcurlee]

Thanks all !! sorry for the late reply _ been crazy busy. Mooseman, I just ordered the Shudder Fix and I'll try it when it gets here ! mrrsm, if that doesn't fix it, I'll start in on what AI has suggested. That's pretty cool by the way !! It's been a really good truck so far ,, 5yrs in and 45,000 ish miles
I'll report back when I know something.

 

[tcurlee]

Yeah, I know its been a while. The truck just passed the 45,000 mile mark so i thought I'd take it in for a trans flush before I tried the the " Instant shudder FIXX " I took it to the Chevy dealer I bought it from and mentioned the vibration I was feeling. They road tested it and called it a torque converter shudder and thought the trans flush would fix it. It seemed like it did 'initially' but returned.
I opened the hood today to put in the Shudder FIXX but am not able to locate the trans fill tube ?!
I figure GM didn't include one so how am I supposed to put it in ?? Any suggestions ?

 

[azswiss]

Needs to be done from underneath the vehicle.

How to Open, Check and Fill Chevy Silverado 1500 Transmission Fluid

 

[tcurlee]

Looks like a major pain in the butt !! So, if I open that plug up and fluid runs out - I'm supposed to let it ?? GM is making vehicles hared and harder to work on . I guess by design :-/ If that shuddering is something they know about and my truck is still under extended warrentee, what am I supposed to do ???

 

[azswiss]

Definitely not as nice as a dip stick, but doable. Manual transmissions and axles have had this setup forever. The fluid is supposed to be level with the bottom edge of the hole. If some drips out then you are OK, if a bunch flows out then it is overfilled. If none comes out then reach in with your little finger and see just how low it is below the edge of the hole. If you do not get any on your finger then it is low.

Note, the truck needs to be on level ground otherwise you will get misleading results.

If you need to add fluid then you will need to pump in new fluid until it starts to drain out of the hole. Let it stabilize (no more dripping), clean the hole, replace the fill plug, and then torque to spec.

If the shuddering continues, like @Mooseman says above, I would take it back to the dealer.

 

[Mooseman]

If it is dribbling out when you take out the plug, you might have to take a little out to allow the amount for the Shudder Fixx. If it's low, put in the SF and then top off. I'd maybe use a syringe with a hose to do it as the SF's small squeeze bottle might not get into the hole right.

Those 8 speeds were a problem for GM.

From Google AI:

A class action lawsuit has been filed against General Motors (GM) alleging that their 8-speed Hydra-Matic 8L90 and 8L45 transmissions are defective, causing issues like shuddering, lurching, and delayed acceleration. The lawsuit covers vehicles from model years 2015-2019 and potentially beyond. It claims GM concealed these defects from customers and instructed dealers to assure customers that harsh shifts were normal.

Here's a more detailed breakdown:
What the Lawsuit Alleges:

• Defective Transmission:
  The lawsuit claims the 8-speed transmissions, particularly the Hydra-Matic 8L90 and 8L45, are defective and cause various problems, including:
  
  • Shuddering and shaking while driving.
    
    
  • Lurching forward.
    
    
  • • Delays in acceleration and stopping.
      
    • Other dangerous driving conditions.
      
• • GM's Concealment:
    The lawsuit alleges GM knew about these defects but didn't inform consumers.
    
  • Dealer Instructions:
    It further claims GM instructed dealers to tell customers that harsh shifts were normal, even though the transmissions were defective.
    
  • Financial Injury:
    Plaintiffs claim they would not have purchased or paid as much for the vehicles if they had known about the defects.
    
  • GM's Response:
    GM has denied the claims and stated that most class members have not experienced issues, therefore they lack standing to sue.
    

Affected Vehicles:
The lawsuit covers vehicles from the following brands and model years equipped with the 8-speed transmission:

• • Chevrolet: 2015-2019 Camaro, 2015-2023 Colorado, 2015-2019 Corvette, 2017-2023 Express, 2015-2023 Silverado.
  • Cadillac: 2016-2019 ATS-V, 2016-2020 CT6, 2016-2019 CTS-V, 2015-2017 Escalade.
  • GMC: 2015-2019 Canyon, 2015-2019 Sierra, 2015-2017 Yukon Denali XL, 2017-2023 Savana.
    

Lawsuit Status:
The lawsuit is ongoing, with class action certification having been granted in some cases. Some sources say the lawsuit is still in progress, and others say GM has issued a safety recall for some of these vehicles.

If the dealer gives you pushback, tell them about the lawsuit. I'm pretty sure they know. However, I can't find any lawsuit that includes 2020 or later. This one seems to be the main one. Maybe contact them with your issues and maybe they can have it changed to include later years.

Consumer Class Action Lawsuit Against GM 8-Speed Transmission

If you purchased or leased a Cadillac, Chevrolet, or GMC vehicle equipped with a Hydra-Matic/8-speed Transmission & would like to learn more, please contact us.

www.gm8speedlawsuit.com

I drove a 2023 with the 8 speed that belonged to a dealership doing parts deliveries and it did the herky/jerky when slowing down. To stop it I would put it in N while slowing down. Can't say I remember the TC shuddering though.