Kevin0311

Half cup or bottle of liquid in cup holder will show it also on mine.

I have a high country and have removed the adaptive ride control fuse with no change in vibration at highway speeds. I have driven in L9 which the internet says disables the DFM and still vibrates. My 2019 High country with NHT (max towing package) 6.2 did NOT vibrate

Trust me i highly doubt it is the wheels, they balance with the tires, i have been down this road with my 23 with different rim, tire combinations and spending the time getting the roadforce number in the single digits with no fix my24 now has 4500 miles on it and does the same as my 23 with highway speed vibration 70+ mph but probably 40% plus less noticeable. now that my 24 is similar to my 23 i do believe it is a flaw with the truck design not specific to just a handful of trucks with majority of drivers not noticing the vibration.

i have noticed supercruise sometimes like op on some roads/sections but others straight as a arrow and i have traveled alot of roads east off the mississippi over the last few years. when it get weird i just take over for several miles the set it again.

2019 6.2 63k miles no dfm issues, oil lines replaced (leaking) 2023 6.2 33k miles no dfm issues but highway vibration issues 2024 6.2 1500 miles no dfm issues

Since my last post i found no “fix” some times was good most times felt vibration 65+mph. Dealer said could not duplicate so attempted to find and fix on my own, nothing found on the interweb for solution seems like was only a few inquiring about issue like this. to sum up i replaced the following during my 33k miles with the truck new rear rotors new rear driveshaft new tires roadforced balanced on 20” rims that did not vibrate on my 2019 hc multiple swapping of 22 inch tires on the 22 inch accessory GM wheels to finally get them to road force balance well within spec. changed diff fluid leaf spring rubbers retorqued u-bolts for leaf springs removed fuse for adaptive ride control removed tonneu cover nothing fixed or stopped it, the 20” wheel/tire setup seemed to lessen it but still could see a bottle of water in the cupholder shaking even on perfect road. my last thing to try was a new truck, picked up a 2024 traded in the 23 and felt it alot less but i did feel it for first hundred highway miles, second hundred did not seem to notice so conflicting results as of now. Truck has 250 miles currently. feels like a wheel weight fell off but trust me it is NOT as my tire guy and myself sat there one day with the 22” setup swapping and flipping and moving tires to get the roadforce numbers low, in the rears at both 3 and fronts were mid teens one and other 21 i believe. always felt it in the seat, arm rest never in the steering wheel

Good luck getting it fixed, a few of us have and continue to deal with this.

I laid on the ground looked under with flashlight and saw 1 rib/fin from pinion to top so according to photo it is AAM. GM one has what looks to be 4 rib/fin. Last Saturday i towed my 2500lb trailer on the highway, my 4WD was on due to snow on the roads when i first started driving my 55 mile trip, about 1/2 home it went to some slush then basically wet roads. When roads were down to wet i picked up speed as did other traffic, i was doing 75 with zero vibration.......in 4wd high. Today i installed new oem rear rotors (dial indicator did not move clamped to jack stand with rear axle in D in garage) although inside of rotors did have alot of buildup no issues found. Took a ride on the highway in 2wd and i will say still 95% no vibration felt, nothing in the seat a tiny tiny bit in arm rests but that could have been regular road conditions all though smooth not perfect. Don't know if fluke or 4wd at higher speed had loosened/warmed up something or what, in winter 4wd is use often but not highway speeds. No idea what changed to make it better. Going on a trip south in several weeks will report back what happens.

If you have the GM rear and i have the AAM then i would basically rule out wheel bearing/locker/axle problem in the rear because what would be the odds, if we both have the same and one of us finally gets a fix and happens to relate to the brand of the rear axle assembly then might be something to try on the others.

where did they clamp the wires for the pico test? Do you know what rear your truck has an AAM or GM one? GM has 3 fins on top AAM does not. Info in this link: Mine is AAM .5" AAM rear: 9.5" GM rear: AAM Front: GM Front:

last week i put original tires/wheels that the truck came with on and same vibration. Ordered new oem rotors and they showed up yesterday will install them this weekend and check for hub runout when all apart. Drove to Bristol TN and back over the weekend 1700 miles and could find no rhyme or reason or condition to get it to change, vibration from 68-75 the worst, seems to fade some above 75 but still there. Rotors, hub runout (looking for bent axle) and rear diff locker next areas to look at, changed the diff fluid last week (with oem fluid and gasket) before the trip south and all looked good back there no excess metal or chipped gear, all bearings looked fine. i did have my tire guy unmount my tires from the rims and check the "true/balance" of rims and they were all out some but one was 4.5oz out of round, these are OEM GM accessory wheels. I do not know what they should be but i would think close to true 0 but don't know, he remounted tires, rotated 180 degrees on rims from what they were and rebalanced, all balanced out with weight but roadforce was off quite a bit on all, one was a 49 with the machine showing the best it would be able to get by adjusting things again (rotating tire on rim) would be 45 others were under these numbers but upper 20's was best. All the tire info means to me is needs weights to get balanced, doesn't matter anyway as no different in any position on the truck front/rear/left/right. I still believe something out of balance on the truck driveline and will continue searching. Aero has crossed my mind but nothing looked out of wack when i had the truck up on my lift doing the rear diff fluid. My 2019 i owned before this never had a issue same 6.2 with 10 speed same trim. GM customer service: I did take to my local dealer to have them look into my vibration concerns described in my posts on this forum, i was charged a fee and their diagnosis was could not duplicate customer concern, some irregular tire wear might be causing the vibration that the customer is feeling. With 5 GM vehicles currently in my garage was disappointing to get that answer and no help to fix the problem. Trust me i know the saying if you want it done right have to do it yourself.

8 or 10 speed transmission?

Elimination update 3/5/24 New driveshaft no change proper torqued U bolts no change removed Adaptive Ride Control fuse no change as far as vibration at highway speeds removed tonneau cover no change Adjusted cold TP from 30-36 no change I am starting to believe it is DFM related or transmission related. Wish my truck was one of the ones without the cylinder deactivation that were produced, that would eliminate DFM and bring it to transmission.

Yes leaf spring U bolts, this is the thread, usefull and good read most is. I did check my bolts on the ground using 60ft lbs setting, all rear (2 on either side) got half a turn to get to 60, fronts were all ready there using X pattern to check. Did not plus 130 degree as seems the proper torque is 59 lbs plus 130 degrees. Wont be on interstate to try for a while yet. I live 10 miles away from interstate where i can get up to 70 plus and doesn't seem to show any change with temps only does in/out minor vibration above 68 mph ish all the way up to the truck shuts off over 100. like a wheel weight missing but not consistent but in and out. Mine was not there brand new off the lot, picked truck up in Michigan and drove 800 miles home and few thousand more before noticed it. There was a TSB on the 14-18 and up to 20 trucks about retorquing u bolts. Worth a shot i figure.

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.

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.

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

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.

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.

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

notice any difference driving handling/or ride with the 305?

Any idea if you have the AAM or GM rear axle? The RPO codes would tell or looking under at the rear end. I have the AAM one. There is two different manufactores of rear ends (front and rear pairs). https://bobistheoilguy.com/forums/threads/2019-thru-2021-gm-half-tons-two-axle-suppliers.358182/ different oem oils but photos in link show difference.

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.

Update: Dealer could not duplicate, drove 14 miles no abnormal vibrations or noises found. did say that 2 of my tires were wearing "abnormally" but doesn't say what two. I do see very slight edge wear on fronts but that doesn't cause rear vibration and has done for several thousand miles with these tires/wheels on, rotated 3 times and roadforced balanced as many it never changed or moved. I will probably order 4 new tires of a different brand over next few months to have the summer setup ready for a trip in mid march, until then the studded snows go back on tomorrow for the 6-12 inches of snow inbound. fyi the pinion seal leak was excess grease from manufacturing process that flung after warmed, and i agree as left no puddle just spots under truck. truck has 19k miles got the wheel tire setup installed 9 months ago probably 15k miles ago. OEM 22 bright chrome with Michelin defender ltx m/s.