2015 YUKON NOISE IN CABIN

FogDucker · November 5, 2016

You do know that GM once had an official memo for the roof repair but have since pulled it - no official reason but suspect due to the bows coming undone again - so it's definitely the roof, and I do not think we'll see a future fix from GM

Reduce inputs into the vehicle and/or the "rip" roof fix are the only ways to go

I'm still not convinced that the roof is in play. My dealership pulled my headliner down to inspect the bows and they were intact, while I had the buffeting. Maybe they pulled the TSB because they found it to be irrelevant?

If it was body mount related, what's involved in changing them?

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The Zip · November 5, 2016

The issue from a high level stems from weight saving efforts which resulted in paper thin sheet metal. To keep the sheet metal from vibrating (booming) and flexing (buffeting) it absolutely HAS to be attached firmly to its braces. In our case, the roof, due the roof panel being compressed from the edges, wants to pop off of the roof bows rather than be stretched tight against the roof bows (how they should be). As a result, the roof pops off and you are driving in a giant drum. This is a manufacturing defect.

... I made some plastic pieces to wedge between the roof rack rails and roof. You could make some out of a 2X4's if you wanted to test this (yeah, that would look rather 'neck on one of our trucks) When they are in place, zero booming and buffeting. Remove them, both come back. Keep in mind my dealer put Dynamat on my roof and lots of extra glue to hod the roof to the bows. When the bows again became detached, the issues returned. Put the roof back onto the bows, the issues go away. I know of no other better way to confirm root cause than to be able to make a chance and get an issue to come/go at will.

Find a way to pin your roof down and you to can get the truck you thought you were buying.

Sheetmetal density is different from gens 2, 3, and 4, but no difference from one gen 4 truck to another that doesn’t exhibit issues on this thread. Kind of agree with your assessment and evaluation with the detached bow piece. With the difference in suspension/length/engine size/ and tires, there could be multiple fixes, one solution may not fit all. You are not the first one to rig up something on their truck to get some satisfactory relief.

Good post though, keep refining the plastic wedges then paint them body color, only you and the dealer will ever know . Disagree with rigging your truck then thinking this is what you paid for.

boazEarl8 · November 5, 2016

It's still speculation re: improved body mounts, but here's picture and link if anyone wants to compare to a 16 .. best way is to go test drive some 17s

http://www.tahoeyukonforum.com/threads/2017-yukon-xl-denali.85107/page-4

Wrench589 · November 6, 2016

It's still speculation re: improved body mounts, but here's picture and link if anyone wants to compare to a 16 .. best way is to go test drive some 17s

http://www.tahoeyukonforum.com/threads/2017-yukon-xl-denali.85107/page-4

Hard to tell. Would need to know which mount this person took the person of, as there are 3 or 4 different part numbers front-to-back in the SUV.

One way we can confirm whether or to GM changed the body mounts is by the part numbers. Once the parts catalogs are out for the 2017's, we can chance vs the 2015-16. And in case GM, is playing any funny business and went back to the 15/16's and updated the parts numbers without the usual showing the old part number superseded with the new one, I made a compare list of the parts numbers for my 2015 about a year ago. Now, a part number change isn't proof the body mount was changed to address the buffeting. But it would be suspicious!

Could the body mounts be a factor? Absolutely. I found numerous technical papers over a year ago published in SAE and other industry related organizations that were specifically about body droning and pulsing noises and several about the role body mounts plays in the final result. Essentially, the body mount is barter the frame-to-body stiffness system, and hence the resulting natural frequency. A bad selection can make a big difference.

And to add to the the story, the new platform (2015- SUV and 2014- pickups) use an all new "shear type" body mount to reduce horizontal motion/jiggle. From the info. Could find, they do this by restraining the horizontal movement via some kind of sleeve inside, or something like that. Essentially, with a slight bit of horizontal movement, the body mount "bottoms out". Could,this affect the transmissibility of any and all vibrations from the power train and/or rolling gear (tires, wheels)....absolutely.

Still need something to respond to all that vibration. Something like a big drum skin. Wonder what it could be......

Wrench589 · November 6, 2016

I'm still not convinced that the roof is in play. My dealership pulled my headliner down to inspect the bows and they were intact, while I had the buffeting. Maybe they pulled the TSB because they found it to be irrelevant?

If it was body mount related, what's involved in changing them?

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Marc, did you have a look at the cross bows when then had it apart? They are the flimsiest things possible. Even if attached, it no wonder the thing still booms like a drum skin. I suspect that is what GM concluded - that even if they keep the roof skin attached, the cross bows do not offer sufficient stiffness to resolve the issue. So, no point in trying. And of course, it's not likely GM will ever change the design of the cross bows or add more ..... totlly impractical in a completed vehicle. Best plan is to deal with the complaints and change the design for next time.

Elripster · November 6, 2016

We can go round and round on body mounts, shocks, etc... but at the end of the day, the truck must tolerate the real world. I suggest for all having issues that they pin down the roof and report back.

swdan1 · November 6, 2016

Any thoughts on why some of the vehicles exhibit the booming/buffeting and others do not? We have a 2016 Cadillac Escalade with no issues whatsoever.

Contrary to that, we also have a 2016 Z71 Tahoe (my daily driver) which has both the booming and buffeting and has now been in the shop for a month..

Elripster · November 6, 2016

We are talking about tolerances. The Cadi might be Ok. If so great. Others, not so lucky

Frank

zfasts03 · November 6, 2016

So yesterday morning. Drove 8 miles, ~38 degrees outside, had thumping in rear from cold shocks that resonated some in cab. Later in the day... Drove it the rest of the day about 45 more miles, no thumping. NO ISSUES at all. Temps 50-60 degrees.

Cold oil in shocks adds to the sound issue.

If mine stays the way it currently is, I like the truck a lot. Crossing my fingers that with time and mileage it holds up like it should.

I keep my cars for a long time and have expectations of minimal issues as it ages.

I have a 20 year old Dodge Ram 1500 4x4 pickup that is still running strong. It is the rust that will send it to the junkyard.

Edited November 6, 2016 by zfasts03

The Zip · November 6, 2016

Any thoughts on why some of the vehicles exhibit the booming/buffeting and others do not? We have a 2016 Cadillac Escalade with no issues whatsoever.

Contrary to that, we also have a 2016 Z71 Tahoe (my daily driver) which has both the booming and buffeting and has now been in the shop for a month..

The most common thoughts on this thread are the roof, suspension, AFM, ANC, thin sheet metal, rear axle, tires, wheels, and body mounts. If a truck does not exhibit any of these issues, some folks even say it's the people not the trucks. GM may correct some of the issues on generation 5, but for this one they are just throwing stuff on the wall to see what sticks.

As for your trucks, the glaring differences (suspension and AFM) will be up to the dealer to get lucky, 'cause you won't be able to do anything about them and maintain some type of warranty. Your Escalade is not out of the woods, there is about a half dozen owners on the thread that had some of the worse problems. So don't change anything on your Cadillac, you might screw something up.

Elripster · November 7, 2016

I'm still not convinced that the roof is in play. My dealership pulled my headliner down to inspect the bows and they were intact, while I had the buffeting. Maybe they pulled the TSB because they found it to be irrelevant?

If it was body mount related, what's involved in changing them?

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"Intact" can mean a lot of things. The roof can be touching them at rest and lift and buffet at speed. Find a way to strap something to the roof and hold it down. If the issue is unchanged than maybe you have other issues. Otherwise, the roof is the large expanse of sheetmetal that can change the interior air volume and cause the buffeting.

Frank

SierraMyst · November 7, 2016

It's still speculation re: improved body mounts, but here's picture and link if anyone wants to compare to a 16 .. best way is to go test drive some 17s

http://www.tahoeyukonforum.com/threads/2017-yukon-xl-denali.85107/page-4

Per Nissan's tech paga...

Nissan's Titan and Armada are using "hydraulic body mounts" to reduce vibration.

Maybe all of these body on frame vehicles exhibit vibrations, but it comes down to the materials and parts the manufacturer used to eliminate them.

And GM choose the cheapest part available.

Leslie Wasson Green · November 7, 2016

The roof was never an issue with my Yukon. That was the 1st thing that was inspected.

Edited November 7, 2016 by Leslie Wasson Green

FogDucker · November 7, 2016

"Intact" can mean a lot of things. The roof can be touching them at rest and lift and buffet at speed. Find a way to strap something to the roof and hold it down. If the issue is unchanged than maybe you have other issues. Otherwise, the roof is the large expanse of sheetmetal that can change the interior air volume and cause the buffeting.

Frank

Could you speculate on how tire balancing can influence/eliminate buffeting if the roof was a factor? Are you suggesting that my out of round tires (since fixed on 2 different sets) caused my roof to shake?

zfasts03 · November 7, 2016

As Elripster mentioned he can make this stop by wedging pieces under the roof rack cross rails to prevent roof movement. Maybe adding a molding to the outside will reduce flex and eliminate the speaker/subwoofer effect.

So, how would it be to attach to the outside of the roof either longitudinally (preferred for cosmetics and air flow) or maybe transversely a body side molding (w/symetrical profile).The 3M two way tape and the polyurethane molding is energy absorbing and the molding would add rigidity to the panel. It can also allow for protection of the roof panel from damage when carrying cargo on the roof. The molding could easily be body color and be a standard feature on new models and a add on by the dealer as per a TSB for those who complain about the booming/buffeting from the roof.

I estimate the moldings would be 1" wide and be place longitudinally directly between the raised stamped areas of the roof. The moldings would need to be thick enough to sit about 3/16" proud of the stamped ridges. It would run a similar length as the roof side rails, maybe a little longer.

If a longitudinal placement does not resolve the cabin noise then a transversely mounted configuration may need to be explored.

I remember working as a Dodge Tech about 25 years ago and seeing the installing of moldings down the roof as part of a roof rack install on a Dodge Caravan.

Edited November 8, 2016 by zfasts03