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Posted

my problem is with the Michelin defender on OEM accessory 22 inch rims.  My 19 i traded in had 20" same tires no issue.  

 

Do you have a tonneau cover i forget if i asked? I rolled my soft cover up and truck still does it at hwy speed so not that.

Posted (edited)

Funny you should ask about a tonneau, because I was wondering if lack of one might be the issue, in that wind turbulence might cause the issue, especially since the issue comes up only at freeway speeds. I might try to drive with the tailgate down tomorrow to see, because today the vibration was more significant than usual at 80mph, whereas it's normally noticeable between 65 and 75mph, give or take, and starts to smooth out when I get into the 80s. But, my hopes aren't high now that you say you feel it with a tonneau, although it's possible that our two trucks have similar symptoms but from different causes. Kind of like when my friend and I both had Suburbans, and you know the buffeting you get when you have one window down at freeways speeds? Well, his truck actually bounced up and down because of it, while mine just buffeted. His ended up as a lemon buyback because of it, and rightly so. But, why his bounced up and down and mine didn't, we'll never know. 

 

In my case, I now know there is something wrong with stock 22" wheels, or tires, or both, in my truck. With the base Denali 20" tires and wheels, the vibration is less pronounced and lessens at different speeds. Perhaps mine is like my friend's Suburban in that we will never know. In your case, you said the stock 22" wheels and tires were perfect. Too bad you aren't closer (I actually used to live in NY), so we could put my 22s on yours to see if it really is your OEM accessory 22s and/or Michelins. But, there have been others in this forum that have expressed the same issue, so it really could be that GM just isn't consistent with these trucks. Maybe they're "made in the USA with foreign parts"! 

Edited by MrLeadFoot
  • 4 weeks later...
Posted

New complete rear driveshaft showed up today, will install soon but still have winter tires on so won't be able to tell if made a difference for another month or so. New OEM was $420 shipped to my door, was a cheaper gamble then new set of rubber, if doesn't make a difference then onto something else.

Posted (edited)
37 minutes ago, Kevin0311 said:

New complete rear driveshaft showed up today, will install soon but still have winter tires on so won't be able to tell if made a difference for another month or so. New OEM was $420 shipped to my door, was a cheaper gamble then new set of rubber, if doesn't make a difference then onto something else.

Here's what I am noticing. When the vehicle is cold, it doesn't seem to vibrate, but when it warms up, it does. And, it vibrates at a certain highway speed range, just like a bad tire or rim would. Now, as far as I know, previous iterations of this truck have had a transmission issue, and one of their resolutions was to use a different transmission fluid. Well, what if that different fluid HELPED, but did not completely fix the real issue, and they have the same issue again? If you had the "Chevy Shake" and the new fluid improved the condition, maybe after such a terrible shake, you might not notice what you and I are noticing, you know what I mean?

 

Just thoughts.

Edited by MrLeadFoot
Posted

I hear ya but my 19 was same motor same transmission same trim level, never had a issue with that truck 63k miles. differences from my 19 to 23 are 22" wheel/tires, adaptive ride control, different gear ratio (19 had NHT max tow package), different front/rear gear assemblies (19 was GM this one is AAM).

I understand a 1/4 oz weight would be very noticeable (i have done alot of research) but think of this as a 1/16 oz or even less like play in the yoke that goes into transmission or a U-joint that has just that little bit of play.  This is why i am starting here with a new driveshaft, i do not remember having this vibration the first few thousand miles (i would say up to 5k miles was fine), gm could not duplicate but i will find and fix this. 

Posted (edited)
48 minutes ago, Kevin0311 said:

I hear ya but my 19 was same motor same transmission same trim level, never had a issue with that truck 63k miles. differences from my 19 to 23 are 22" wheel/tires, adaptive ride control, different gear ratio (19 had NHT max tow package), different front/rear gear assemblies (19 was GM this one is AAM).

I understand a 1/4 oz weight would be very noticeable (i have done alot of research) but think of this as a 1/16 oz or even less like play in the yoke that goes into transmission or a U-joint that has just that little bit of play.  This is why i am starting here with a new driveshaft, i do not remember having this vibration the first few thousand miles (i would say up to 5k miles was fine), gm could not duplicate but i will find and fix this. 

OK, thanks for the clarification. Sounds like you and I are the only ones that want to see this resolved. Others bailed on their trucks, and likely many more are living with it.

 

Could it be a malfunctioning ARC shock? The reason I ask is because I did notice, when test driving before I purchased, that trucks with the ARC seemed to have what felt like a little vibration after hitting a sudden road surface change, like running over a slightly recessed manole cover. It is like a little aftershock (for lack of a better term) when it recovers from the "impact". None of the other trucks, AT4 and otherwise, felt like that. Those other models bounce and float a lot more on bumps and depressions as their way of combatting road surface imprefections, while our shocks to a "better" job at absorbing them. I read that our shocks adjust every 2 milliseconds which makes me wonder if it's possible that an errant shock never stops its movement? Just a theory, but I think it's feasible that because the shock is still reacting and responding, even it is at the wrong time, no code is thrown, so GM thinks there is nothing wrong and tell us it's "as designed".

 

But, I learned a long time ago that generating computer code errors is only as good as the programmer who wrote the code. I once had an '84 Trans Am, (hmmmm GM again) with an electronic carburetor. It would heistate upon acceleration from a stop. Kept throwing a mixture-control solenoid code, and I swapped out the solenoid several times, but nothing changed. Finally a programmer friend of mine said that it's possible that something else is wrong but the compute rcode logic was written in a way that made the programming THINK it was the solenoid. So, I traced the logic, and learned that the mixture-control solenoid did its thing based on the position of the throttle. The throttle position sensor had it's own error system, but never threw a code. Nevetheless, I removed the TPS and tested it. Turned out that it lost continuity and generated an "open" circuit at the bottom end of its range, which equated to coming off a dead stop. Replaced it, and my symptoms and mixture control solenoid error went away. That's when I learned you can't always trust electronic systems just because there is not code thrown, and a bit of thinking is required, which GM apparently doesn't think they have time for. Either that, or they know exactly what's wrong, and don't want to share because they have no fix and/or it's too costly for them to fix.

 

I just wish there was a way to run without our ARC "enabled" just to see if it's shock-related.

Edited by MrLeadFoot
Posted (edited)

the arc shock can be disabled in 2022.5 and older have read how to do this and would think similar in the 23+, this is a step in my process when other things are eliminated/not found to solve is to try to disable without damage, make it act like a "normal shock" maybe as simple as taking out a fuse or will contact this company.

https://www.youtube.com/@xineering/videos

 

 

The newer gm air ride "tuning" i have red about seems to adjust also to speed so possibly the ARC is also "tuned" to be stiffer at about 65 mph causing more frequency vibration transfer into the cabin since the shocks are now stiffer, i remember reading a while back a interview with the person/company that was the main man responsible for ARC tuning, i would have to search that out again.  ARC is different from MRC was the big take away from that article. 

 

Searching around seems every generation in last 15 years have had vibration issues, with TSB issued right up to 2022 i believe

Edited by Kevin0311
Posted
4 hours ago, Kevin0311 said:

the arc shock can be disabled in 2022.5 and older have read how to do this and would think similar in the 23+, this is a step in my process when other things are eliminated/not found to solve is to try to disable without damage, make it act like a "normal shock" maybe as simple as taking out a fuse or will contact this company.

https://www.youtube.com/@xineering/videos

 

 

The newer gm air ride "tuning" i have red about seems to adjust also to speed so possibly the ARC is also "tuned" to be stiffer at about 65 mph causing more frequency vibration transfer into the cabin since the shocks are now stiffer, i remember reading a while back a interview with the person/company that was the main man responsible for ARC tuning, i would have to search that out again.  ARC is different from MRC was the big take away from that article. 

 

Searching around seems every generation in last 15 years have had vibration issues, with TSB issued right up to 2022 i believe

Nice find, but I think you need to then install standard shocks, ot just use the same shocks. 

  • 2 weeks later...
Posted

Yes it is installed but still have the studded snow tires on the truck.  Have been up to highway speed once and very very hard to tell but doesn't seem to be any difference, summer tires will tell right away on the highway.  Next plan of attack is to try different driving modes to see if it does adjust the suspension, then take the fuse out of the adaptive suspension setup to see if that changes anything. About a month until summer tire/wheels are put back on i will report back.

Posted

Doing more reading the 14-19 Silverado's some forum members torqued the U-bolts and saw positive results, and some used spring clamps on the springs.  Many of them had no highway vibration until several thousand miles into ownership.  I did find a TSB about retorque but only went up to the 2021 year.  Either way i will find the torque specs and plan on this as a thing to try next if i put on the summer tires and still vibrates on the highway.

Posted (edited)

What ubolts are you talking about, the leaf springs? It makes sense that something could loosen over time. But, ours vibrate when new. It is possible something is loose, especially since ours were built during Covid, and all that was going on then with parts shortages, substitute workers, etc. In a way, I kind of wish it was something stupid like loose parts, and sometimes it feels that way to me. Like, I feel it in the body of the truck more than anything when I hit a certain speed and my arm is on the armrest on the door. If only I could not touch the steering wheel or that armrest while driving, it wouldn't be so noticeable. Maybe that's why they have the StupidCruise option. 🙂

 

Also, I forgot, when does yours vibrate, does it change with speed or temps?

Edited by MrLeadFoot

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