FogDucker

I hear/feel the V4 mode too, but it's perfectly acceptable IMHO. It's almost like a light drone. I can hear the difference between the two and often just switch to manual mode to eliminate AFM when I'm trying to isolate the buffeting. We've got some buffeters in the San Francisco area, no?

I'm of the opinion that the vibrating and the buffeting are two completely different issues. The tire replacement, re-balancing and an axle replacement made a significant improvement to my vibrating, right up to 100mph. The truck drives smoothly, 99% of the time. I no longer have any vibration issues. In regards to the buffeting, here is my description: Single instances of "the boom" at low speeds over bumps [driveways, expansion joints...]; coincides when rear wheels go over the bump; sounds like somebody flicking a 12" subwoofer with their finger; doesn't always happen; commonly heard on concrete borders between driveways/lots and roads; always noticeable on gravel or brick roads; sounds like it's coming from rear of the vehicle Repeated instances of "the boom" at speeds of ~65km/h and ~115km/h [40mph and 70mph]; not heard at speeds greater than 130km/h [80mph]; this is the "buffeting"; annoying as hell; sounds like driving with rear windows down; sounds like double bass from a heavy metal band using a broken amplifier; 30-70Hz range; not all the time, but most of the time; some road surfaces, even smooth ones, seem to excite it more than others; can be heard more clearly when ear is facing rear of vehicle; fades in and out; happens with seats up, down or folded; more audible from front seats; sounds like it's coming from rear of the vehicle; not all humans can hear it The buffeting sounds exactly like the description of Helmholtz Resonance or "Side Window Buffeting", except that our windows are all up/closed. It's not a new design issue. Mechanically, there is no model or option that is more prone to it. For example: I've got a short wheel base, no sunroof, running on 20's. And it buffets.

So, are we buffeters simply people with unique hearing? Sent from my SM-G925W8 using Tapatalk

Has anyone with a buffeter ever driven one that is perfectly fine? Do they really exist or do all of them have it to some degree as some of you have suggested? Sent from my SM-G925W8 using Tapatalk

I did that too. With the window closed, I used that stretch wrapped and tuck taped it on the interior of the glass. Better seal with my hack but not air tight. I've also been adjusting the door stops, one full turn at a time. Still can't stop the buffeting at 40mph and 70mph.

Yeah, I've been experimenting with that. Unfortunately, no results as of yet. The experiment continues...

Here is a link to that post. I hadn't read that and will try the paper test. Agreed that vibrations and buffeting are often confused. I had both [though the vibration was minor] and now I have only buffeting. The buffeting is eerily similar to what some Tesla and Porsche owners have experienced. Solved by adjusting their hatches. I bought a roll of stretch film today, commonly used to wrap boxes for shipping. If the weather cooperates, I'm going to seal the entire hatch from the outside. The fact that you found a non-buffeter and not all have one, give me hope that we're just an adjustment or rubber seal away from having a quiet vehicle.

@Yahtzee: Thank you for taking the time to record, edit and publish this! @everyone: I might be seeing something that isn't there, but does anyone see small movement of the glass? Watch the edge.

I wouldn't consider it a safety issue either, at least in my case. It's just annoying as hell. I don't enjoy driving my Yukon because of the buffeting. I wish I could park a buffeting version and a quiet version side by side and compare them. This must be a solvable problem! Does anyone know how to measure vibration/movement of the hatch while the car is moving at 40mph and 70mph? Chaser car with a good camera? ;) GoPro suction cup?

@Booty: I remember your posts. In fact, I remember going outside to push on the tailgate glass just as you mentioned, but could find no flex. Can you tell us how you are able to determine if the seal isn't proper? Is it just a matter of inspecting the rubber seal when the glass is lifted? I just checked mine again just now with a flashlight but can't see anything wrong from the outside. The gap looks consistent and pushing on the glass allows for minimal flex. There doesn't seem to be any stop adjustments as there is on the tailgate.

The only adjustable stops I can see are about half way down the hatch. I've gotten better results with it a few turns from flat. Too far extended or too "closed" and the boom / buffeting was worse. I've read the paper trick to measure for a the right seal too - simple but effective! I haven't personally tried that yet. The bump stops at the bottom of the hatch seem to be only that - rubber bump stops. I've done some more foam insulation experimentation - tape some on, drive. Move it around and drive some more. The attached picture is the best I've gotten it. The low speed bump boom is significantly better. 40mph / 70mph buffeting is still there, but has improved. Styrofoam along the bottom, especially in the corners have made the biggest impact for the low speed boom. The hatch *just* closes on it's own - I sometimes have to give it a bit of a push to keep it from re-opening. Next steps are to focus on the area above the bottom hatch where the 3rd row seats fold - that *is* new for 2015/2016 and it's possible that the hatch is bouncing off that. The styrofoam I'm using is the soft flexible kind, about 3/8" thick. The fluffy stuff seen in the cargo area wasn't as useful as it compressed too much. It would be awesome to see more owners conduct this same experiment to see if they can *influence* [not necessarily fix] the boom/buffeting via the hatch.

Yes, I stuffed the glass portion with foam, making it very snug to close. Unfortunately, I did that experiment with the main hatch and don't know which helped/hurt. For now, I'm just focusing on the hatch, specifically the top. Be sure to listen for the slow speed bump boom and the 40 mph/60 mph buffeting!

The buffeting and booming has improved with foam placed at the top of the hatch. See the orange arrows in the picture [the left piece shifted before I took it]. I don't believe the stuff at the bottom makes a difference, but I'm trying to change only one thing at a time. Can anyone else reproduce?

Purple unicorn - they don't exist! ;) I wonder if GM is testing / measuring a good one and a buffeting one side by side. How does one measure buffeting? Is there an app for that? ;)

I did not personally check it. Yeah, it jumps but no more than my friend's 2014 Tahoe which is quiet. Sent from my SM-G925W8 using Tapatalk

I forgot to mention that - my roof was fine the whole time. The field engineers took down the headliner and all the bows were intact.

Same here. 2 new tires, many balances and a complete rear axle. It did make for a smoother ride, but had no affect on the buffeting. I believe that the vibrations and the buffeting are two distinctly different issues. The buffeting may all be related to Helmholtz resonance. There are many interesting articles about this online, such as this one or this one. The examples speak mostly about when one or more windows are down and the car drives at speed. I think we're experiencing a variant of this with our windows up. Bumps and/or swirling air [different pressures, "vortex shedding"...] may be causing the hatch [or rear glass] to move - bouncing in/out and causing the buffeting. We are inside a really big speaker and the hatch/glass is the woofer. The Tesla folk had a nearly identical experience, solved by correctly fitting the rear hatch stops. So did some Porsche models - all had hatches. Who knows, maybe the slow speed "boom" might simply be the hatch shifting around in ways that it shouldn't. I've been experimenting with this over the last couple of days and have been able to manipulate the buffeting via the rear hatch and/or glass. I've adjusted the bumper stops and placed styrofoam pieces in various places, both on the hatch and the rear window seal. Sandwich it in top, bottom, sides... I've got the buffeting to get worse and better by limiting the amount of inward travel. Where exactly, I'm unsure. Air/pressure/Helmholtz also fits nicely with what we've observed - buffeting can affect any of our K2XX SUVs irrespective of wheelbase size, engine size, transmission type and options. All of our SUVs do share the same seals [?] and hatches. The pickup trucks do not have this problem. Happy New Years to all.

Maybe it's a robot? ;)

I bought the center console organizer which uses the rails. It's very useful!

A reader left an interesting comment in the AutoGuide article - hiring a third party that specializes in Noise and Vibration to diagnose this issue. Does anyone have any idea how much this might cost?

My Yukon was at the dealership for a few days last week for the following: rear axle replacement; rotor to rotor headliner removed and inspected; bows were attached; they applied more adhesive to be on the safe side possible road force balanced the tires some more; [unsure - haven't received paperwork yet] The above was in addition to another road force balancing session and 2 tire replacements. Results? It still buffets, peaking at 40mph and 70mph. I experienced exactly the same buffeting at the same speeds in the 2015i Suburban that I drove while my Yukon was in the shop. Longer wheel base. Different transmission. Different engine. Larger wheels. Same buffeting. The truck definitely drives more smoothly, especially at higher speeds. The field engineers were able to record a measurable improvement in vibration aftera ll the above was done - I don't doubt that. I'm beginning to agree with what Wrench589 and others have been eluding to - this is a more deeply seeded resonance issue with the frame/body and not simply some out-of-spec parts that vibrate. Unfortunately, this is not my area of expertise nor do I have any interest in learning about it. I just want a quiet truck for my family!

The SUVs buffet/boom at 70mph [and at 40mph]. The pickups vibrate at 70mph. Let's assume that it's the same root cause for a moment. We might rule out: transmission: occurs on proven 6-speed and new 8 speed suspension, at least parts of it: pickups have leaf springs; SUVs have coilover; occurs on traditional *and* magnetic suspensions tires/wheels: to your point, many of us had had multiple balancing sessions and replacements LWB vs SWB - they both do it I've had my wheels road forced balanced at least once. They've also replaced the entire rear axle assembly - rotor to rotor. Both did result in a smoother ride, especially at higher speeds [90+mph] but did not change the buffeting that is prominent at 70mph. They also took down my head liner; the bows were intact. What else is common between all the different models, regardless of trim or options? Merry Christmas!

2015i Suburban booms and buffets. 2014 Tahoe does not boom or buffet.

The roof pops up in the 2015i Suburban I'm in when I close one door. It buffets at 60kph and worse at 120kph. My friends 2014 Tahoe has the same roof movement when closing the door, but does not buffet at any speed. I just compared them side by side in the driveway. Sent from my SM-G925W8 using Tapatalk

Yes, but there was no happy ending. lol