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Posted

i encourage every one to do it cuz it will detached sooner or later and to force the company to realize it's fault >

Posted (edited)

Individual fixes handle certain things, something like what Norcal is doing. However, a fix for shaking and vibration will probably do nothing for the truck that buffets or has pressure. An individual fix of how and what Norcal is doing may ultimately be an overall fix for the shaking and vibration piece on platforms with larger wheels and/or longer wheelbases. Norcal, have some of your customers log on and talk about their experience.

 

Speaking for the folks that are not having any of these issues, a redesign in 2022 for looks will naturally be in the cards, but a redesign to address these issues won't change what's going on. If GM could adjust the tune on AFM for droning, get a solid weld on the roof bows for buffeting, lower the truck and adjust the springs (maybe check wheel size) for shaking and vibration, and adjust the mics for pressure, they may just have this figured out.

Edited by The Zip
Posted

Pinion angle and vehicle height may have helped with vibration in some of your customers trucks, but this alone is not the issue. My truck has been totally stock since Feb 2014 and it never shook or vibrated.

Gm should swap part by part from a good one to a bad one to see which part corrects the problem

Posted

Mine was fine,however, all but the most forward bow have since come detached and issues are back.

 

what issues did yours have initially
Posted

After following this problem for months. The fix is obvious. 1) rip the head liner, and weld the roof bars to the roof. Then find an interior shop to put it back together.... with some dyno mat.

 

Then people talk about less than 15 lbs road force. Obviously the truck is very sensitive to any irregularities in the tires. But the road force is just a Band-Aid or a mask. There must be a resonant frequency that is causing the vibe. and Mr. CA with his new lowering springs is changing the dampening levels on the shocks and springs, so it's eliminating that problem. I doubt it's the pinion angle.

 

GM knows all about it. Why they prefer to go through all the law suits, buy backs, and bad reputation on the internet is beyond me. That is the baffling question.

Posted

Buffeting and vibrations while related are two different issue. Vehicles vibrate for all sorts of legitimate reasons, like rough pavement. Buffeting is a change in air pressure in the cabin which can be due to vibrations or resonances between the air within and outside of the cabin. To address the buffeting, and for the most part the booming, the roof simply has to be fasted down.

 

Since our stock trucks have a rake, as speed increases there is a lift phenomenon due to the Bernoulli effect (air in cab is still while air over roof is moving) and force due to pushing air up as the vehicle travels. At the point those two forces cross, buffeting can occur even on a smooth road. I have noticed repeatedly that if I increase speed I can get buffeting to decrease. Unfortunately the speed limit does not appreciate that. If the roof is detached, of course it will boom and buffet due to the road inputs.

 

One thing lowering is doing is leveling the vehicle. The lifting forces then are dominant and so that component of buffeting is eliminated. If lowering is also addressing a resonance issue then two sources of roof excitement are addressed.

 

However, in all cases, the buffeting is like the running nose and the detached roof is the sinus infection. We need to push our dealers to fix the problem and not focus on the symptom which they can easily dismiss as "normal". GM admitted guilt when they issued the roof TSB so if you fight that angle (roof properly repaired, symptoms only help find problems, not the problem themselves) you will win.

 

Frank

Posted (edited)

Did they balance the tires below the 15rf rating?

 

Was size tires you got on there

20" Oem Continentals.

Edited by Ozzii
Posted

Has the issues been resolved with recently manufactured suburbans? Located a 2016 Z-71 with 18" wheels. I really don't want to pay 60 plus and have these issues. I have owned 5 suburbans in the past and with no problems. All before 2014 model years.

 

What should I look for on test drive?

 

Thank you

Posted

Has the issues been resolved with recently manufactured suburbans? Located a 2016 Z-71 with 18" wheels. I really don't want to pay 60 plus and have these issues. I have owned 5 suburbans in the past and with no problems. All before 2014 model years.

 

What should I look for on test drive?

 

Thank you

Listen for buffeting at 45mph and 70mph. It sounds like a back window is open.

 

Listen for booming noises when driving on gravel, snowy or bumpy roads at low speeds. It sounds like somebody flicking a subwoofer.

 

Feel for vibration in the steering wheel, console or seats.

 

Try to negotiate a set of Michelin's in, and ask them to road force balance them to 15#s or less.

 

Good luck! They're awesome vehicles, absent of any of the above issues!

Posted

I have 22 inch tires. I am not sure what all they have done, and to my relief it is not my problem now. I have been rewarded a full refund without having to go to a hearing. I am so done with GM products at this point. 78 days in the shop on my 16 and that was after a 100 plus days in the shop on my 15. Enough is enough! We never got to see the inspectors report on this last one. Once they received the report, they settled.

Posted

Did they balance the tires below the 15rf rating?

 

Was size tires you got on there

They did everything they could possibly do. I am sure they did the 15rf rating. The inspector came down last Wednesday for the hearing that was scheduled this week. Not sure what was in the inspection report, but they settled on Friday so I guess we will not know what was in there. Either way, I am very happy to be GM free!

Posted (edited)

After following this problem for months. The fix is obvious. 1) rip the head liner, and weld the roof bars to the roof. Then find an interior shop to put it back together.... with some dyno mat.

 

Then people talk about less than 15 lbs road force. Obviously the truck is very sensitive to any irregularities in the tires. But the road force is just a Band-Aid or a mask. There must be a resonant frequency that is causing the vibe. and Mr. CA with his new lowering springs is changing the dampening levels on the shocks and springs, so it's eliminating that problem. I doubt it's the pinion angle.

 

GM knows all about it. Why they prefer to go through all the law suits, buy backs, and bad reputation on the internet is beyond me. That is the baffling question.

The RF tire thing might be a band-aid but I must say ever since dropping down to the 20s and having quality tires installed with all numbers below 15RF, the truck is buffeting free. This is coming from someone that couldn't ride more than 15min in the truck before getting headache and sick feeling due to the horrible pressure/noise. And I was only days away from taking a substantial loss and trading in on a '14 Denali. I am not certain it will stay this way but 6k miles to date and still satisfied. The funny thing is, I am almost positive one or more roof bows are not attached as there seems to be way too much free play in sheet metal tapping roof but at this point I'm not having them touch the roof.

 

Regardless, these trucks are way too sensitive and I'm sure multiple items can cause the issue.

Edited by ajs800
  • Like 1
Posted

Has the issues been resolved with recently manufactured suburbans? Located a 2016 Z-71 with 18" wheels. I really don't want to pay 60 plus and have these issues. I have owned 5 suburbans in the past and with no problems. All before 2014 model years.

 

What should I look for on test drive?

 

Thank you

I really think these trucks should not ride on low profile tires and wheels so I bet your 2016 with 18" wheels would be fine. Mine is a 2016 built October 1 with 18" wheels and it is the best car I ever owned. Test drive yours on all sorts of roads. If you don't here booming or see a water bottle vibrating in the coup holder you will most likely be fine.

 

The ones that ride well are great vehicles.

Posted

Mine was fine,however, all but the most forward bow have since come detached and issues are back.

 

What attaching the bows solve at first. I'm currently test druvung some escalades

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