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Posted
20 hours ago, Elripster said:

I did model them in SolidWorks but I have not built to the model. I just made them to-fit with my band saw.

 

So my prototypes are urethane bar stock.  I used (2) 1.5" square pieces (24" length) glued together but going forward I would use something harder.  Maybe something like this...  https://www.mcmaster.com/#=1ava2d9

 

I also suspect going to 36" will help as well.  I use 2" wide weather stripping between the bars and roof itself.

 

I drilled holes to get the radii and then cut into them tangentially with the band saw to try to mimic the shape of the roof racks.  I did have to purchase the roof racks separately since my truck did not come with them.

 

The good news is that I am completely happy with this truck.  I went up a size to some more off road worthy tires since I camp and occasionally get the truck into 4 low (locker works!).  It rougher as expected but it's not different now than any other truck with larger harder tires.

 

If this does not get rid of the booming, Dynamat or equivalent will.  Buffeting is a very low frequency phenomenon where the booming is higher in frequency and well addressed by Dynamat or similar.

 

image.thumb.png.15a8355a51829b29d85690cce6897047.png

 

 

Thanks, Frank.  I plan to build mine next week when my cross rails arrive. 

Posted

I have a dilemma. My dealer admitted there’s been a problem with ‘15’s and ‘16’s coming back on a regular basis. He said he hasn’t seen it with ‘17’s and 18’s. It’s the end of the year and he’s offering 20% of MSRP on an ‘18 2WD Denali if I trade in my ‘15. I was one of the lucky ones who bought my ‘15 from him 3 years ago and didn’t have any noise or vibration problems. $62k out the door with TT&L and extended warranty on a $75k sticker. The catch is, I sign the papers tomorrow - the Denali is sight unseen until it arrives next week. The GM said I can cancel the deal if I don’t like the two arriving next week. Is the deal too risky on an ‘18?

 

Posted
1 hour ago, ChicTrucks said:

I was one of the lucky ones who bought my ‘15...Is the deal too risky on an ‘18?

There is not enough owner input if the ‘18 will be risky or not, but the difference in these trucks is whether you were lucky or not.  It took 7 years for this current generation change, so whatever is going on with the unlucky owners will probably not change until the generation 5 (21/22) version.  The body style, suspension, and chassis remains the same, adding bells and whistles year after year is not getting to the heart of the issue.  Hats off to the owners attempting to mitigate the issues, but also being one of the lucky owners, I wouldn’t be looking to push that luck.

Posted

I would say too risky.  This issue is a design flaw.  The trucks have terribly thin sheetmetal that is poorly supported.  The next body restyle will hopefully address it.

 

Frank

Posted

I keep hoping for changes to the Yukon. 2007 was a bad model year. There were so many improvements over the next 7 years and it became a great SUV. The dealer told me they were getting killed with the ‘15 and ‘16 models. He said they aren’t seeing it on 17 and 18. They can’t keep the Denali in stock. I also learned the Yukons come on a truck with crappy black wheels. The 20’s and 22’s are added at the dealership. They’re shipped completely separate and aren’t assigned to a car. There’s a warehouse of wheels...they grab a pair and stick them on a Denali before putting it on the lot. 

Posted

Ya know, you can blame wheels, etc... all day long.  The bottom line is every other vehicle runs them just fine.   These trucks require unicorn grade carparts to be livable which even if you find them, will become sub-unicorn grade when the age/wear.  Anyway, your money, spend it where you'd like.  You asked if it  was risky, I am an engineer and I would suggest steering clear until the next body restyle.  

 

If you look up under the headliner, you will see  there  is very little metal up there.  The  roof bows are very flimsy and they support a paper-thin roof.  That is the heart of the issue.

 

Frank

  • 2 weeks later...
Posted
On 12/22/2017 at 1:55 PM, Elripster said:

You can just see them here...  

 

image.thumb.png.ccb3088c633fd2fafd7ee1671ade927e.png

 

 

I made mine with a 2x4 and foam weather stripping.  It helped with the buffeting and ear discomfort so now I plan to build a better-looking one. 

IMG_1067.JPG

Posted (edited)

After driving the 2018 Yukon Denali for a week, I decided to trade in my ‘15 and buy it. The 10-speed transmission is smooth and the noise and pressure are non-existent. My family says this one is smoother and quieter than my ‘15. I had them remove the 22’s for 20’s before I drove it. Don’t know if the wheels on an ‘18  make a difference.  I love it! Really impressed. 

Edited by ChicTrucks
Posted (edited)

About 150 or so posts back in this thread, I commented about wanting to purchase a new Suburban, but because of the problems mentioned here, I would wait. Well, the wait is over. I picked up a new 2018 in December. I test drove the vehicle specifically looking for the booming and buffeting problems around 40 and 70 mph. If I tried real hard I could pick up minimal buffeting and the booming was similar to what I've had in my 4 previous Suburbans. Neither were excessive enough for me not to purchase this vehicle.

 

The vehicle has 20" wheels, 3.42 gear ratio, a sunroof, Continental all-season tires, the 5.3l V8. I have noticed that at about a steady 40 mph, the transmission is in a gear that allows the engine to be lugging while trying to maintain that speed, and you can sense some buffeting trying to happen. It almost sounds as if the exhaust is creating a drone at that rpm range under load. It doesn't seem to matter whether it's in 4cyl or 8cyl mode. By selecting the tow/haul mode, the lugging goes away because the transmission then shifts to a lower gear and the minimal buffeting stops. The same situation happens at about 70 mph and by switching to tow/haul mode, the lugging/buffeting goes away. It seems that 40 and 70 mph are the points where the transmission is near the shift point. I suspect some of the concerns with these vehicles result from the programming of the transmission shift points resulting in the transmission staying in too high of a gear for too long so they can claim better fuel mileage.

 

I'm very happy with this vehicle and I'm glad I waited. I may have been lucky enough to find a good one and I hope it stays that way. When you're driving what amounts to an empty airplane fuselage on wheels down the road, noises will surely show up. 

Edited by dbdave
  • 3 weeks later...
Posted (edited)

I have a 2015 Chevy Suburban LTZ and unfortunately it has the booming and buffeting  issue bad! I drove for 10 days and couldn't figure out why my ears were plugging. Finally it got so bad that my daughter got car sick and it gave me the worst headache of my life. We took it back to our dealer and they have been trying to fix it for 2 months! So my question is do we get something different or are the newer models less prone to this issue?

Edited by Speedbealady
Posted

Good that the dealer is making an attempt, unfortunately they won't figure anything out.  You have a truck with detached roof bows, the dealer would have to do something like what was mentioned by Shaun and Elripster.  If not, look for something different 'cause these trucks won't change until 2021, when the gen 5s come out.

Posted

They have already checked the roof bows and claimed they were attached, applied noise cancelling material, changed the muffler, and replaced tires and rims.  I'm bummed because these trucks are quite dazzling and fit my family perfectly.  I also have a 2002 and its been great! Maybe a 2014 even though the interior isn't  my cup of tea. 

Posted

Everything you mentioned has been tried, your dealer is attempting to make this truck tolerable for you.  Keep your expectations very low and don't be dazzled by just the bells and whistles.   

 

The 2014 (gen 3) is a decent truck, though technologically dated by today's SUV standards. 

Posted

Test drove a z71 Tahoe recently.  I was able to do an extended (20-30 mile) test drive.  Noticed something was off but couldn't tell exactly what.  Kept getting a strange pressure feeling in one ear.  While driving on the highway I looked in the rear view mirror and could see both headrests on the rear captain chairs shaking badly.  It was then that I realized the vehicle had this constant vibration and drone noise.  Dealer tried to tell me it was due to new tires that haven't been "broken in".  Even had me test drive another z71 with him on the highway.  Could feel the vibration in that one also.  Walked away without purchasing it.  Didn't want to deal with the headache (literally).   

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