Elripster

Yep, thin sheet metal that won't stick to the roof bows is definitely a huge part if not the problem. Frank

They definitely not the same thing. Completely different frequencies. Sent from my SM-N910V using Tapatalk

My bows came over of the course of weeks. I suppose you could try that and see how it works. That really is the only way to know, by trying it. Maybe the best approach is to get the bows fixed and then install it right away to keep them attached? Frank

If your roof is detached from the cross bows the booming and buffeting will occur from V4, road irregularities, wind speeds, etc... The roof just has to be attached as designed or all sorts of things will excite it. My 2003 was more tolerant of windows down as well likely due to the thicker sheet metal and the fact that it was much less aerodynamic. Frank

Wait, it is indeed totally normal to buffet with a window or two down. The flimsy roof might make it worse but otherwise all modern aerodynamic vehicles that I have driven do this. This thread is about buffeting with the windows UP. If you don't have any buffeting with the windows up you are good. Frank

Suggest they remove the headliner and go for a drive, with you if necessary. There will be absolutely no doubt the roof is flexing after they get to observe it realtime. Frank

Excellent! Just filled out the form.

If you all want to split hairs, these are all light duty vehicles. The medium duty classification starts at 14,001 lb GVWR. Heavy duty starts at the 26,001 lb GVWR. I would say why not compare the suburban to its competitors like minivans and similar SUV's for a more production digression. Frank

You misunderstand my point. The roof jumping means it is not attached. Secondly, our roofs are much larger and thinner than the older vehicle you mention and thus require more bracing not to buffet. You might have a vehicle that for whatever reason does not excite the thin roof but it would appear in our case there too many disturbances to have an unrestrained roof and no buffeting. Sent from my SM-N910V using Tapatalk

To add, mine were fixed, problems went away, came detached again, problems came back. I am not 100% convinced that everyone who had the TSB and still has the issues has actually verified their roof bows are attached. If a tech inspected them, did said tech go for a drive on the freeway with the headliner out and actually verify no movement in the roof or just look at the roof while it was at rest? Did the owner shut a door and see if the roof jumps? Or pound the roof and see if the whole expanse resonates? These things can verify that the roof is in fact still attached and if so can verify that despite attached roof bows the problem still exists. Frank

Appreciate that any structural modifications employed by GM require the vehicle be recertified for crash safety. Dealers cannot therefore make structural modifications unless in the very unlikely changes GM permits it. Obviously if you do it on your own you can do whatever you want. Frank

Well it is safe to say it is not adequately braced for that gauge of metal.

I too notice the "soft spot" below the windows on the rear quarters. I suspect that spot might need some attention after the roof. Frank

My dealer used Dynamat and it did help with the booming. Even today the booming is not as bad. However, it does not address the buffeting as it does not stiffen the roof. We did discuss bed liner but if there is any overspray the potential to ruin an interior is pretty high. Otherwise, it would likely do the trick. Frank

With the roof the thinner material means a lower natural frequency which can and clearly does cross paths with the disturbing frequencies. A thicker section will resonate at higher frequencies which is what you really want here. Essentially you want the body structure to resonate at a frequencies higher than that of the disturbances which requires more stiffness whether that be from thicker metal, more bracing, etc... Otherwise, if the disturbing frequency and natural frequency cross cross, you get constructive interference, standing waves and other unpleasantries. One way to think of this is in terms of a spring and a mass. If you put a thinner lighter spring, the natural frequency of the spring/mass system goes down. Of course if you reduce the mass the frequency goes up but here the force is more in bending (at the edges of the roof) and the change in stiffness impacts the natural frequency more than the reduced mass of the roof and thus thicker metal wins by increasing the natural frequency. Frank

I think it is also important to ensure a fixed roof is still fixed. You might do something as simple as shut the door and pop the roof off of its bows. Frank Sent from my SM-N910V using Tapatalk

Actually, that is exactly what the problem looks like to me. The roof wants to pop up and the glue simply cannot hold it down, at least not for very long. I am perfectly Ok with keeping an open mind. I really do like everything else about the truck. I just need this issue fixed. Frank

I can't find my GoPro... Will keep looking. I probably brought on one of my last 4X4 trips, didn't use it, and tucked it away somewhere. Frank

The freeway ones are better and are still on my GoPro. Still, it is hard to see it flex. However, with that much area, only a little flex is required to really change the pressure within the vehicle. Frank

These are not all off them, I apparently need to add the freeway ones...

Let's try this.. https://drive.google.com/file/d/0B1UQB0HJVe3XMGVuOXp0cWljLTA/view?usp=sharing https://drive.google.com/file/d/0B1UQB0HJVe3XcHR2TF9vd090VDg/view?usp=sharing

My videos are on my Google Drive. I don't know how many email address requests I can keep up with but why don't I get a few of yours and maybe you can assist with the sharing. Sharing is good you know. I tend to think that the main issue here is structural rigidity and bonding. The roof bows need to be bonded when the metal is this thin. I think addressing the vibrations are indeed band aides. Let's face it, vehicles vibrate, it's normal, the body structure just needs to resonate at a frequency well above that of the disturbance. If GM can figure out how to keep roofs attached they will have taken a step in the right direction. Frank

Well it would seem since they a) know this, and b) managed to address it on prior generations they should have no issue addressing on this and future vehicle generations... at least one would hope. Frank

I can understand where you are coming from. So, the Dynamat will reduce the booming significantly. Maybe your dealer can install it on the roof and rear quarter panels below the window. However, there is one issue that I would watch for and that is the bow behind the sunroof coming detached. If one sees the roof lifting there than leaking is likely to develop at some point. On my truck that sunroof-bow was reattached and then came off again. To me that was the straw that has me pursuing a repurchase. I can't imagine dealing with a leaking sunroof for years to come. Frank

I saw it on USA Today (net article) as well.