Wrench589

Don't forget, a V6 engine is inherently much, much rougher running than a V8 by design. Has to do with the torque pulses from the crankshaft/firing order as well as the exhaust pulses. Been that way since V6's started showing up en-mass in the 80's. Only smooth running V6 engines are the ones with a built in balance shaft, which I don't think the Chevy engine has. So, don't spend too much time trying to get it to run as smooth as the 6.2L. That is one of the smoothest engines on the planet. The new generation of Chevy V8's has a different firing order/crankshaft design than the old Chevy small block, to further refine the mechanical and exhaust pulses, and it works. I don't believe the V6 has anywhere near that level of technology. You know the old sayin'...can't make a silk purse out of a sows ear!

Yes, the 2500's and 3500's have the same issue. Go to the HD forum on this website and there is an active thread there.

And, the new process requires lapping of the gears. Hmmm. That sounds like a step to get missed or not done properly! Of course, it would be interesting to know when the industry in general went to 2 cut gearing. And, is the 2014 pickups/2015 SUVs the first generation that GM went to 2 cut gears? Interesting.

So, this is very very interesting. Did some research and found a couple of interesting things: 1. AAM is interestingly ex-GM. When GM went out of the driveline business, they were going to close a bunch of plants. Some ex employees bought 5 of these plants and started AAM. 2. AAM's website has some very interesting info. They talk about their 2 cut gears. I found some information on what that means. Older technology was what they call 5 cut machining process. The new 2 cut process eliminates 3 steps where they cut each gear in one step. So, less steps means less cost. But, supposed to result in more accurate, quieter gears. Backlash setups are different. Now, it wasn't possible to make 2 cut gears years ago, but supposedly modern, precision machine centers have allowed 2 cut process to be done now. So, makes one wonder. It all sounds good on paper, but like most new, high tech processes....things can go awry. Would not surprise me if AAM have messed up something with this new process, and of course since they are the sole supplier (supposedly), no surprise that many of the replacement attempts ended up with the same vibration. If this is what's going on, GM has a mess on their hands. First, they need to get the problem sorted with AAM. Then, are they actually going to replace all the gear sets in every vehicle? Definitely not. They will only replace the ones they have to. Customers that demand it. And, this is not a safety issue, so don't expect a recall. TSB at best.

It seems that in mine, there is some vibration when the pressure/buffeting (aka drone) is present. I have driven all versions - Chev, GMC, short (Tahoe, Yukon), long (suburban, Yukon XL), with and without ANC and Magnetic Ride, 18", 20", 22" - they all did it. Slightly varying severity, but they all did it. I agree that this new generation is significantly stiffer in an attempt to provide a more "European" type ride. Unfortunately, GM screwed it up. They made it stiffer but missed the "ride quality" portion. I have driven my share of BMW's and Audi's, and not one of them displayed the harshness of these new gen SUVs. They are stiff and handle great, but the road harshness has been somehow isolated and there are no ridiculous "buffeting" sounds or any other pain in the ass noises. GM obviously does not have the technical wherewithal to build a vehicle at the caliber of BMW or Mercedes, so they should have stuck with what they know - sofa on wheels! This generation of vehicles will be the learning studio for GM and maybe the next generation will actually be correct. But for now, they suck. And no amount of telling the owners that their expectations are mis-aligned will change that. You may love yours. That's great. Everyone has a different threshold of when a sound becomes a noise. Yours is obviously higher than others. But make no mistake - this is a real issue, and has been observed by dealers and factory engineers. Most of us are suffering with it out of lack of any option. I also guess that GM knows exactly what the problem is. It's likely something major, like the entire stiffness of the vehicle results in a resonance of a major component and generates the buffeting. And there is no fix for it, short of a complete redesign. And all the farting around with road force balancing and rear end exchanges and blah blah is a band aide diversionary tactics to wear out the owner into submission, or frustrate them into going away (via buy back, lemon law, BBB, simply trading it off at another brand). And for those that don't notice it, they can keep on selling new units and posting record profits.

No, I'm talking about the Magnetic a Ride suspension option. I removed the fuse to disable the electronically controlled shocks and found the buffeting noise, and road harshness, was still present. As I said, the vehicle did "wallow" more around corners and through large dips in the road since the shocks go to the default (low) damping rates. But the issues were still present. Agreed that all the various trim levels will share identical frame, suspension and body hardware...to a point. Springs may be different. Shocks are definitely different between lower trim levels and the top with Magnetic Ride. I doubt suspension bushings are different but the top trim levels (Denali and LTZ) could have more acoustic padding in the cab or something like that. Normal for the manufactures to do something like that. BUT, as I've shared several times, I have personally driven several different trim levels for a week at time (when ours was in the shop) and ALL trim levels have the road harshness, vibration in the steering wheel, and the dreaded buffeting - active noise cancelling or not, magnetic ride or not, short or long version (Tahoe vs Suburban), Chev vs GMC, 18", 20" and 22" wheels. You name it, I've driven them all. They all do it. Some worse then other, but the difference is marginal and irrelevant to me. Based on industry proven root cause failure analysis techniques, we would rule out design differences then, and focus on the commonalities. That's common sense. So, frame, body, body mounts, suspension arms, etc. all the stuff that is common across the platform. The answer is there.

I'm not sure the changes made with bulletin 5429 would do much for the harshness of the ride. The reason I say that is based on two observations of my own. First, I disabled the active ride control on our Denali (by pulling the fuse). I could certainly notice a difference in that the vehicle "wallowed" more going around corners and thru big dips in the road and in/out of parking lots, for example. But the harshness felt going over tar strips, cracks in the road, and gravel was essentially the same. The second reason is we have had several rentals while ours has been in the shop for various repairs. All but one were non Magnetic Ride equipped, and with either 18" or 20" wheels/tires. And, the harshness was identical. So, I don't attribute the harshness to the magnetic active ride shocks per se. I think it's the entire suspension, frame, body mount system that is so stiff, it transmits every impact that the suspension gets hit with. Softening the shocks and springs may not be the answer. But, would be great to hear from some folks who get the update done and see what they say. I'll certainly be talking to me dealer about it!

Well, could be. If the whole issue is vibration causing a resonant response of the entire frame/body/interior system, then changing the stiffness of something in that system will affect the natural frequency and/or damping. In the case of rubber suspension and cab mounts, both stiffness and damping would be reduced when the rubber gets hot. This would have a big effect on the total system response. Same for tires - hot rubber is softer! You know, I pointed out on the SUV forum that GM has advertised that they have gone to new style "shear type" body mounts. The rubber is secured laterally to reduce horizontal body movement, in an attempt to give these full size trucks a more firm, "sports car" -like ride. I still wonder how much of and effect it is having on all the vibration (and noise for the SUV's) issues we are seeing. Anyone else seeing different characteristics in the hot weather?

What is the muffler fix? I must have missed that one along the way. Still seems that the only reports of success have been rear differential. Nit all, but several. Nothing else has worked, although it haven't kept track if these same successes also had the list of things previously done...such as the roof panel re-glue. If they did, then there actually could be some validity to the notion that all these thing contribute and all need to be addressed. In fact, as I write this, I wonder if that's the difference between rear differential replacements that worked and the ones that didn't! My dealer is still waiting for their new "Pico meter" so they can take the vibration readings and report the GM. Yea, I know, what a ridiculous wait. But I can only assume the folks at Pico can't keep up with orders from GM dealerships, and we always have to wait till the end up here in Canada! Hoping once they take all the vibration data, GM will approve them to install a new rear end and maybe I'll be one of the lucky ones and problem solved!

It's incredible that the 1/2 ton pickups, the HD pickups, and the SUV's all have a related issue. Just looking between the 1/2 tons and the HD's, there isn't much running gear that is the same, yet the vibration is present in both. Even the frames are different. Beyond technical explanation. Normally when we troubleshoot machinery, or do formal RCFA's, we look for the commonality between machines that are exhibiting the same problem. But in this case..... It's almost crazy! Other than the cab and box, what else is the same??? So now, we're talking a multitude of defects across the 3 platforms. Almost hard to believe, but there is no question the problems are there. About the only possible connection is that GM bought all the pinion and ring gears from the same supplier and there is a latent defect in all sizes due to some quality control issue, that shows up with the issues being reported. And as I've said before, changing the gears and not solving the problem does not prove the problem is not caused by the gears, just means the replacements have the same defect as the ones removed. As since the replacements came from the same supplier, that is not a stretch! I would love to see someone install a set of aftermarket gears in one of these trucks. Have the differential rebuilt by a reputable gear shop. Be very interesting.

I agree that this looks very promising. Even the folks on the pick-up thread are finally getting some reports of their vibration issue being solved with new rear ends. Not all, mind you. But of course, if the same defective parts or settings are used, then of course it won't solve the problem. My guess is that GM knows exactly what the issue with the pinion and ring gear are, but getting enough sets to replace all the problem pick-ups and SUVs, while tooling up to build the 2016's, is proving more than their crappy supply chain can deliver. So, they throw some parts from the "suspect" bin at the customer hoping it will either satisfy them or buy GM some time. I do recall a report about 6 months ago on another website altogether that said they replaced the entire rear end assembly, housing and all, and the buffeting went away. I also shared some of my research several month ago where I found several papers and a GM TSB that dealt with vehicle cabin boom as a result of pinion gear-mesh issues. So, this would be not big magical revelation if it truly is the root cause. The frustrating thing is that the gear tooth backlash was the very first thing my dealer checked. So, either they didn't check it correctly, or the specs they worked to are not correct. I suspect the latter. Looking forward to my next conversation with the service department. Keep the reports coming in!

LOL!! I'll check the manual again, but may be different than the US version. I see that a lot here in Canada. No rationale reason, other than the French section that you all don't have. Zip - yes, you did provide the link. Thanks very much. Unfortunately, takes me to GM's US site and when it detects that my ISP is in Canada, prevents me from downloading. Directs me to the Canadian site, which has the exact same manual I have with the vehicle. Nice trick GM! Thanks, guys!

I will say that the manual that came with our Yukon is extremely poorly written. It tends to be more of a description of what the feature can do instead of instructions on how to operate it. And ours has the keyless start, which the manual completely ignores when it comes to certain instructions. For example, it describes how to turn on the Accessory power using the key, but provides not a single word on how to turn on the Accessory power when the vehicle is equipped with keyless start. One would think that GM could have been bothered to add instructions for those that bought the $80,000 version!! Once again, thanks for nothing, GM. Bottom line, it's a bit of a POS.

Going from the pickup to the SUV will be like going from the frying pan into the fire! Go check out the "Yukon Cabin Noise" thread in the SUV action of this website....not only do you get vibration but as an added bonus you get the dreaded "boom" sounds, which end up sounding like wind buffeting. Except your windows will be closed. And if you're really lucky, it will be so severe you'll actually feel ear pressure and may even get headaches like some of the folks are experiencing. Then, GM will start by doing the TSB that removes he headliner (from your brand new $80,000 vehicle) so they can re-glue the roof skin to the flimsy struts because the factory glue let go. Then they will try Roadforce balancing a bunch of times. But, you won't notice the vibration, because the noise is so annoying it's all you will focus on when you drive it. So, I guess you'll have that going for you.... Yea, my Yukon has vibration and cabin noise. I will say that loosening the body mounts, driving it, and re-torquing did reduce the buffeting to the point where I don't feel pressure anymore. But still hear it. And did not improve the vibration at all. Now, the vibration is mainly felt in the steering wheel and it fairly high frequency (buzzy) but the seats do jiggle a fair bit as well especially if there is no one in them. That said, I find a lot on new vehicles do that. Seems like the stiffer chassis and suspensions result in the seats jiggling a fair bit. I don't know if that is connected to the vibration felt in the steering wheel or not. Just a comment to those who's rear end was replaced and did not see an improvement. My concern is that since all GM is doing is swapping parts, and not telling the dealership or the customer what the root problem is with the ring gear, there is absolutely no way for the dealership to know if the new parts are just as flawed as the ones coming out. Classic definition of insanity - keep doing the same thing over and over and expect a different result! Not going to happen, GM. If there is a flaw in the ring gear, or the carrier, or the housing, or even the bearings as one poster suggested a while back, then installed the same flawed part, new or not, ain't gonna solve it! Just wasting everyone's time and money. GM would be better off saying "we don't know the problem, we are working on it, and as soon as we have a fix we will correct your vehicle". At least all this wasted time at the dealership and false hope would go away and be less frustrating. But what do I know...I'm just the lowly customer (with the $80,000 in my pocket). GM is infinitely smarter then me ... they got my money, didn't they!

I've done a fair bit of thumping around, and is have found I can generate the "boom" in several places. Certain spots in the headliner. Opening and closing the rear doors, from the detents in the mechanism that holds the doors open, the floor in the back between the bucket seats, to name a few. Admitidly, I did not investigate the rear hatch area, but it seems to me that many places will excite whatever is booming. The challenge is to find what is actually responding to these various inputs to generate the boom. May be the rear hatch, but seems a stretch that an impact from the floor would be able to find a path to the rear hatch (which hangs down from the hinges). But, noise and vibration are complicated, and anything is possible. Please report back if you do indeed isolate the source of the boom. That is definitely the key to the solution. I sure have to wonder if the engineers at GM know what it is. My guess is that they do, but the cost to correct it is more that a few pennies, so GM will not do it. It's not a safety issue and sales have not been affected. There are tons of these on the roads and most people love them. My experience has been 4 out of 4 have the boom, so it is definitely in the design. I guess some people don't hear it. Let's face it, lots of people live next to noisy streets or train tracks, or airports. I guess we all have a different threshold of when a sound becomes "noise". So, GM can sit on the sidelines on this one. But, if the owners figure it out, might be able to either insist on a fix from GM, or maybe come up with something to alleviate it. Never know. Just a comment on the "white" stuff inside the hatch. That would be a sound absorbent, not a deadener. There is a difference. Absorbent will reduce noise via absorbing the sound wave energy and reducing he remaining SPL. (Literally turns it into heat inside the fibres). A deadener stops something from vibrating and generating noise in the first place. As well, certain deadener will also act as a barrier to noise transmission. The reason a point this out is the the white fabric material will do nothing to stop and vibrating of the hatch itself. It will merely absorb some of the sound generated but the outer hatch skin or more likely, it's there to absorb outside road and wind noise. GM has used virtually no sound deadener in these vehicles. Open up he cover to access he jack, on the left side. Pull that white sound absorbent up and loom at the top OD the wheel wells. They dab a few strands of deadener on there. What a joke! So who know how much the lack of sound deadener play a role in all this!

Actually, it's completely possible to need weights opposite each other when doing a proper dynamic (2 plane) balance. The machine measures the unbalance at 2 separate planes, in this case, the inside bead and outside bead. There can absolutely be unbalance 180 degrees apart, especially with cast metal like aluminum or definitely in rubber compounds like tires. In castings, porosity can form during the casting process. This results in air bubbles or voids, which of course are lighter then the base material. And hence, and unbalance presents itself. And, nothing to prevent the same thing from happening 180 degrees on the other plane. And when you add the tire to the wheel, well all hell can break loose! That said, it certainly speaks to the quality of the tire, the wheel, and/or the balance machine operator. Because, there is also the possibility that the wheel had some unbalance on the outside bead and the tire some on the inside bead (as it was mounted). A proper sequence in Road Force balancing would actually detect that, and have the tire swapped around and mounted such as to cancel the wheels outer bead imbalance. At least as much as it could. And the rest, by weights. So, there is more to it.

So, the fact that changing tire brand changed the response (ie the speed/frequency) of the vibration certainly points to the tires. Now, that can mean the tires are the cause. Or, it can mean the tires are simply part of the system that is responsive. Changing tires can change the mass and /or the stiffness of the tire. Both are key parameters in the natural frequency of any system. Natural frequency will be the frequency a system resonants at. So, any disturbance at the natural frequency usually results in a resonant condition (meaning an amplification of the initial disturbance. Disturbance = residual unbalance in the tires! wheels, hubs, etc. (there will ALWAYS be some residual unbalance left over, even after the best balancing job). This is sounding more and more like a resonant condition. Could be suspension. Could be frame. Could be body. It's all one, interconnected system. May not be an easy fix for the folks at GM. Still, has anyone tried aftermarket shocks? I seem recall some discussion about that.

Worm gear...you mean the pinion gear in the rear differential? I would believe that. This sounds like that kind of issue. And, we have heard of some folks having the issue resolved with the replacement of the "rear end". Still not 100% certain which component in the rear end is the real offender. Pinion? Crown gear? Maybe the bearings? Maybe the housing itself?

As far as I recall, no one has reported that the TSB that re-attaches the roof skin to the struts has corrected the noise issues. Not one time. However, I'm sure GM will insist it be done before doing any other trouble shooting. That said, I don't recall anyone reporting any subsequent issue with the vehicle as a result of taking the headliner down. So, it's not a bad thing to have the roof properly attached, regardless of its impact on the noise problem! You will likely have to let them run their course!

This could be very interesting! Here is a post from over on the pickup thread, whee they are having vibration issues. "Update just got back from dealer. Look at the bearings in rear diff..yes they are too small for it, so when pressed on they spread out. Looks like this may become a recall ...just so that everyone knows they have been working on a fix...it looks like it might soon be here. Waiting on simms as new gear set is bigger. Should get back truck on tuesday. It looks like a bad batch of bearings that where too small. I hope that this fixes my shakes." My Yukon has some of the same vibration issues. But it is of course masked by the noise irritation! It is a string possibility that the source of the booming is he rear differential. After all, the source is mechanically induced boom, from my testing and analysis. And, differential issues have been seen to cause booming many times in the past in the industry. So, this bearing thing is a prime suspect, in my mind. Let's keep our fingers crossed!

Very interesting. May explain a lot. Do know if he issue is bad quality bearings, or the bearings are too small (ie bad engineering)? Upsizing bearings can be challenging as the housing usually dictates the size of the bearing. They may have to re-design the entire rear end housing. If it's the axle bearings or the pinion bearing in the carrier, then the entire carrier whole need to be changed to accommodate larger bearing(s). All very do-able at a cost. Let's keep our fingers crossed that this is the problem and GM steps up and fixes it!

Wow, what a twist. So, it's the software in the vehicle GM claims is copyright protected, and by extension, so is the entire vehicle. Well, I can see the software portion of it. We all own computers, phones, tablets, and every one of those devices base software on it that is copyright protected and everyone clicks the yes box and has no complaints about it. Why should a car be any different. But extended it to the entire car is ridiculous. Again using the computer analogy, Microsoft doesn't claim to own the hardware. That is still mine, to do what I want. But, Microsoft has locked down the Windows operating system such that the user cannot monkey with the code. If GM want to lock down the code, go ahead. But the vehicle hardware is still mine. To flip,it around, if GM is claiming they still own the vehicle, how far does liability of that ownership go? Is GM going to take responsibility if that vehicle is used in a crime, let's say? Or gets a photo radar ticket? Of course not, they will rely on the terms and conditions of the sales agreement to say the operator has that responsibility. But here's what it comes down to. If GM what's to go this way, then they have every right to eliminate sales contracts and instead have licensing agreements. My expectoration is that regulators force GM to be fully transparent to consumers so they realize they are not buying it, but licensing it. Then, let market forces dictate. As we see in computers and other devices, some folks refuse to buy Apple products because the OS is locked down, so they buy Android because of it more open architecture. Likewise some folks use Linux instead of Windows. My guess is GMs competitors will exploit this and offer alternatives to the market, so people will start to select what they buy based on what software it runs, not the actual brand per se. Still, the whole idea is disgusting. Who does GM think they are. Assholes! (Pardon my language, but really....) BTW, my meds aren't strong enough to make a difference on this!! Lol!

And to add to that, let's not forget that GM was basically broke not that long ago. So much so, that they could not afford to develop a new body and a new chassis when they came out with the previous truck body style in 2007. So, they choose to do the body style and leave the chassis, until the 2014 "total redesign". Combined with coming out of near-bankruptcy and the ignition switch fiasco, I'm sure GM isn't exactly flush with cash. So, it really starts to look like they cut as many corners on development costs as they could on these trucks. And it is showing up in these owner comfort issues. Make no mistake - major auto makers make trade-off decisions every day, always at the expense of the consumer. The ignition switch is a perfect example. Imagine some engineer says he needs another million dollars and 3 more months to fully test all the NVH (noise, vibration, harshness) and the product manager says "screw that. NVH isn't a safety issue, so we'll save the money, and most customers wont even know the difference. Those that do, we'll dance around with them till they either get frustrated and go away or get frustrated and trade it off on a Ford. The remaining few that we have to buy back, well, we'll buy them back and put them back on the lot. Won't cost much and and and...." Blah blah blah. They can rationalize anything to make a bad decision! Better go take my medicine now....

Good post, Anon. "The low speed booming over bumps is due to the fact that the sound of the rear suspension has to go somewhere and it resonates in the cab." Ok; but, in a properly engineered vehicle it (a) wouldn't go inside the cabin environment; and, (b) the resonance frequency of the cab would have been damped. That being said, if that statement were 100% accurate, why is it not an issue with all other vehicles? (let's keep it simple...in last year's Tahoe/Yukon line). BTW, the resonance inside the cabin would change based upon interior volume and number of salt water sound absorption bags -- humans and dogs." What's interesting about this is the huge number of technical papers published on the topic of vehicle "boom" or "drone". I counted several hundred papers in SAE alone on the topic based on one search alone. THe bottom line - it is a very common issue with vehicles that has been studies and analyzed to death, by all the auto makers. These papers are all published by various engineers working for one of the companies, be it Ford, GM, Toyota, Hyundai, etc, etc. That tells me that the phenomenon is common. How the manufacturers deal with it is another thing. I highlt suspect that what GM tried to do on this new SUV platform is take the easy way out. Instead of applying more "traditional" methods to design, test, analyze, modify, and correct the boom, they decided to use their "state of the art noise cancellation technology" to do all the dirty work. Problem is, it doesn't work. Why do I suspect that? Because in a GM press release on the Terrain when they introduced it, they said they were using noise cancellation technology to take car or boom sounds generated by lugging the engine for fuel economy. They were boosting about it. Makes me suspicious, to say the least. Now, do other vehicles have booming? Turns out, I would say absolutely. Since delving into this on our Yukon, I listen carefully to every vehicle I drive now. Turns out, my own daily driver, a 2009 Ford Explorer, totally booms. but here's the thing - I never noticed it before. Why? It's not that severe. It only does it over noticeable bumps, and it seems to dampen out almost immediately. And, it not as loud when it does do it. Whereas the Yukon seems to do it over just about any road disturbance, seems to sustain much longer (like a bouncing vehicle with no shocks), and is louder when it does do it (which is most of the time). So, it tah because it's a bigger vehicle? Well, it's been years since I've been in a previous generation Suburban, so i can't say from personal experience. But, seems like other have said the previous generations Suburbans "don't" do it. Which I take to mean it's not very noticable, like my Explorer was/is. As for the acouistic resonances in the cab, I've actually done the calcualtions for the various modes (and there are many of them), and none seem to coincide with the frequencies I have measured acoustically inside the vehicle. The measured are lower then even the lowest calulated mode. So, I suspect that this is not an acoustic resonance, but instead a mechanically/structuraly induced acoustic response. And I have not done any structural modelling to predice those modes - and I likely never will as that is extremely complicated. NOw, I will admit that my calculations for the acoustic mode does not take into account any of the modifiers inside the cab - the seats, the carpet, the console, the salt bags (as Anon call us). But, I believe that those tend to increase the mode frequencies, not lower them, so wouldn't make them align with the measured sound anyway. Still, worth pointing out. So, the comment that the rear suspension is transmitting up into the cab is actually one the prime situations that causes mechanically induced boom in a cab, turn out. So much so that even problems with ring gear runout, backlash, or u-joints can transmit up through the rear suspension and cause boom. But to Anon's point, a properly engineering vehicle will control these to the point where the occupants do not notice them. As for the higher speed "buffeting", I am waffling on whether it is the same thing as the boom/drone, or a separate exciting force and response. I'm not sure. I do know that when the dealer loosen the body mounts, drove the vehicle to neutralize them, the torqued them back down, that the buffeting at 100 kph seemd to be gone - for about 2 weeks. Now, I am starting to hear it again. So, the body mounts definitetly play a role, and that could be th transmission path for whatever is causing the buffeting. Which of course has nothing to do with aerodynamics! But, note that even the body mount adjustment did nothing to improve the boom/drone at all speeds - that remained the same. And then there is the observation I have about how opening and closing the rear doors can also cause the boom. The simp;ly detent in the door mechanism generates a boom that can be heard if you sit in the seat and open/close the door repeatedly. Even my daughter and wife can clearly hear it. (Need to be sitting in the seat - won't hear it standing beside the vehicle). Now, those doors are structurally coupled to the body, so are obviously exciting the same thing that other disturbances are exciting. The question is - what? I still maintain that the only surface big enough to generate enough air movement that a person will feel pressure in your ears is the roof panel or the floor. Most likely roof. Now, a comment on the roof. Yes, there is a TSB to re-glue the roof skin to the struts that form cross-members. So, there seems to be a sense that if that bond is intact, then can't be the roof. Here's the thing - how many folks have seen what those struts look like up close in person? I have. I saw mine when it was apart. Those strusts are a fricken' joke. Flimsy as toilet paper. And, large spans between them. I can still see (yes SEEEE) my roof flexing when anything disturbs the body. Even opening and closing the rear doors through the detents. And if I can see it, then it's moving a shit load by vibration standards!! But what do I know. I just own the thing!!

Great videos, keakar! Pretty hard to argue with that!