2021 Silverado 3.0L Diesel having vibrations on the interstate 70-80 mph

[Pawg]

if it goes away under acceleration, I would look at half shaft, CV, alignment... have a diesel jetta at 80mph it vibrates, coast its fine.  turned out to be the axle. 

[Armydave81]

So...I originally posted this in July of 2021 and here we are in March of 2022.  In January the dealership decided that they would replace all 4 tires in hopes that it would solve the issue.  They use the same exact brand and everything.  Called me to come get it and asked if he test drove it.  Immediately was told everything was good to go and no more vibrations.  Little do they realize that I can see the number of miles he puts on the truck every time he test drove it.  He took it for a 4 mile test drive in an area when the highest speed limit is 45 and its 6 miles to the interstate (the only area where you can put the truck into the parameters to feel for the vibrations.  So, off in the truck I go for my test drive.  As soon as I hit 65 mph, guess what, still there.  nothing ever changed.  Turn around and went back only to hear that, there was nothing else they can do because it was within "GM Tolerances".  I laughed and walked out.  Blew up the Service Managers phone but no return calls.  Took it to a different dealership to have a second opinion and had them confirm I wasn't crazy.  So back to the original dealership I went with the information.  They have had the truck for almost a month and finally got a call with news that the mechanic had narrowed the problem down to the driveshaft.  But the kicker is that the part is on backorder with no estimated ship date.  

 

Now, new question would be, How much damage could driving around for close to 19k miles with an out of balance drive shaft cause?  Transmission? Differential?  U-Joints are a no brainer.  I am starting to research that one and looking for input.  

[pokismoki]

from our past history with chevy trucks, the vibrations in some models have been traced to "COnverter lock up"  usually its becacuase the software is not Slipping the clutch enough to remove the engine lugging at low rpms..  try disabling the tcc in the converter. or have a tuner add more slip rpm to the tcc trans tables in the software

Edited March 25, 2022 by pokismoki

[Armydave81]

On 3/25/2022 at 12:35 PM, pokismoki said:

from our past history with chevy trucks, the vibrations in some models have been traced to "COnverter lock up"  usually its becacuase the software is not Slipping the clutch enough to remove the engine lugging at low rpms..  try disabling the tcc in the converter. or have a tuner add more slip rpm to the tcc trans tables in the software

Interesting information, I will keep it in mind.  Supposedly, the lead mechanic had switched out a driveshaft from another vehicle thus eliminating the vibrations.  Now the waiting game for a new driveshaft. Who know when it will get here.

[pokismoki]

yeah we in the K2 section been through all those parts swappers mechanics before. change, the rims, change the tires, change the axles, change the torque converter, add special rad clamps to the shaft, install special rubber isolators to the steering rack, change your underwear and stick an ocilliscope up your ass...yada yada yada.... Goodluck with the vibe chase

[Kevin0311]

How did you make out did a new driveshaft fix your problem?

[Armydave81]

Update to the issue.  Nothing has resolved the issue and I just rolled over 57k.  The truck has been scoped and rescoped.  Drive shaft replacement fixed the issue found from using the scope but not the issue I am feeling.  The vibrations are definitely still there.  The truck has also been through a pinion angle check and shimmed to bring into GM specs. Still not resolved.  I'm looking to replace the suspension and have the rear diff serviced soon.  Maybe something will come to light with all of this.  I'm also looking to replace the rims and tires but one step at a time to see if one thing or another actually resolves this craziness.  

 

Before you all ask why I never traded it in, there is nothing that they could give me to replace this truck.  I got such a deal before the covid craziness that if I was to trade it in, my payments would literally have almost tripled for the same truck.  

[Saltybeach75]

This is my exact issue! Purchased a 2021 3.0 Duramax with 10 speed transmission in February. Noticed the shudder at highway speeds shortly after (60-80+mph). First dealership - first visit replaced torque converter and said all was good (13 days @ dealer). Shudder was still present on trip home from dealership. First dealership - Second visit stated bad fuel and I just needed to drive all the bad fuel out, stated they would check fuel filter (17 days @ dealer). Got truck home, pick up ticket did not mention fuel filter being checked. No visual signs fuel filter had been checked either. I changed fuel filter myself, found internal mesh liner had pulled away on fuel filter. Shudder still present. Took truck to driveline specialist who did not feel the shudder was due to torque converter, transmission or drive shaft. He felt it was an engine issue, misfire, possibly fuel injector. Took truck to Second dealership - first visit explained issue and showed him fuel filter I took off. They found metal particles in fuel filter housing and on magnet. They replaced fuel pump and flushed fuel system (2 days @ dealer). Shudder present on trip home. Did test drive with tech with diagnostic laptop plugged in, no issues found with fuel injectors. Found transmission to be failing specifically 5th and 6th gears, rebuilt transmission ordered and installed (4 days @ dealer). Shudder present on trip home from dealer. Literally about to trade this truck in!!! Could this be a bad rebuilt transmission? It shifts fine, I don't feel that is truly the issue. I'm currently researching for faulty sensors or turbo issues, ect. Surely someone out there has found the fix for this issue.