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Posted (edited)

So your saying the rear end problem is fixed , but a muffler problem might be the new vibration?

 

I mean if a problem came back 300 miles later then the original problem is isolated to what they replaced right

 

No. The rear end is not fixed. When they replaced the ring and pinion and set the backlash at .07", I believe the "buffeting" (sound only, no vibration associated with this sound) at 43MPH was gone. However, something was not set just right causing a new 'buffeting" sound that is directly associated with a new vibration that is most present at 53 MPH per my post above.

 

In order for the dealer to be reimbursed by GM for the work they do on the vehicle, they must "go by the book". This 'book' is a laundry list of items to troubleshoot. The first item on the list is the headliner fix. Items on the list (in no particular order) are:

 

Headliner TSB

replace tires

"muffler fix"

Backlash testing

a. Ring and Pinion

b. New Chunk

c. New Housing

 

Since I assumed the tires and muffler fix was not the problem based on information I received from the Service Manager in Michigan, and provided proof (via the actual work order), they skipped the first few listed and went to the backlash testing. Speaking of which, I have a new update.....

 

***UPDATE***

I went to the dealership and test drove my vehicle on Friday. Due to the vibration at 53 MPH, they replaced the chunk in the rear end. They also repaired all of the rattles and figured out what the "liquid" substance was coming from the rear view mirror housing (there is a new bullentin out for this housing leak).

 

After driving just 2 miles I quickly notice the vibration was still present and the replacement of the chunk did not resolve my issue. I drove the vehicle back and had a long conversation with my Service Manager. He stated they also reset the backlash at .04 after talking with a GM technical advisor. He showed me the documents that are produced stating what the backlash is/was to be set at and it showed .05 - .07. After talking with the GM technical advisor, the advisor stated this information needed to be updated and told him to set it at .04. Either way, the vibration was still there.

 

He stated that since this did not solve my issue, the next step is to escalate the issue to a specfic engineer that will be in charge of my case and it will be given a case #. He stated the next step is to replace the housing altogether, which he is ordering today as long as the enigineer gives him the 'OK'.

 

I now have a myriad of questions and thoughts going thru my head.....

Did the vibration always exist, but was only noticeable when the changed the backlash setting? Is this truly what is causing the buffeting?

Does this mysterious 'muffler' fix need to be done along with the other fix to be fully corrected?

 

I will have another update as soon as I have something to report.

Edited by cleanfreak
Posted

@Clean: It sounds like things got a little better only to get much worse. Very sorry for your troubles. Thanks for taking the time to update us too. I would certainly call GM to get a case number. 2016's will be out soon...By the time they figure out how to fix yours (they tried all of the "fixes" on mine to no avail), the new ones will be out. This one sounds like a mess. I just ask the dealer to order a 2016 now, or get your money back altogether. Your time is too valuable for this nonsense.

Posted

@jason-Thanks. You are correct, it is a mess and my patience is running thin........I still have a slimmer of hope......

 

***UPDATE***

  1. I have some information that might be useful to some. First, I found out (sort of) what the mysterious "muffler fix" is. It is actually a fix that is not available yet. When the vehicle changes from v8 mode to v4 mode there is a 'stutter' or short vibration during the transition. GM is well aware of this issue and they are working on a solution. The solution has to do with the muffler and the exhaust system. GM will be providing the new exhaust system in the estimated time frame of Sept-Oct. For what it is worth, my vehicle does have this ‘stutter’ transition issue, but it is not very bad. However, it is a major issue for the 2015 Tahoe I have for a rental vehicle. To me, it is funny how some vehicles experience various degrees of the same issue. ***Please note this has nothing to do with the buffeting issue, or vibration issue at 53 MPH***
  2. I am not for sure if this has been made known or not, but a new Technical Bulletin (PIT5429) was released on June 1st to deal with “vibrations” or “Rough Harsh Ride” for Yukon Denali, Cadillac Escalade, and Tahoe LTZ, Suburban LTZ models built before 2/10/2015. These models have the Magnetic ride control Suspension (RPO Z95). My vehicle is not equipped with this, but it might be useful for someone. Please see attachment for the bulletin.

PIT5429.pdf

PIT5429.pdf

PIT5429.pdf

PIT5429.pdf

Posted

@jason-Thanks. You are correct, it is a mess and my patience is running thin........I still have a slimmer of hope......

 

***UPDATE***

 

  • I have some information that might be useful to some. First, I found out (sort of) what the mysterious "muffler fix" is. It is actually a fix that is not available yet. When the vehicle changes from v8 mode to v4 mode there is a 'stutter' or short vibration during the transition. GM is well aware of this issue and they are working on a solution. The solution has to do with the muffler and the exhaust system. GM will be providing the new exhaust system in the estimated time frame of Sept-Oct. For what it is worth, my vehicle does have this ‘stutter’ transition issue, but it is not very bad. However, it is a major issue for the 2015 Tahoe I have for a rental vehicle. To me, it is funny how some vehicles experience various degrees of the same issue. ***Please note this has nothing to do with the buffeting issue, or vibration issue at 53 MPH***
  • I am not for sure if this has been made known or not, but a new Technical Bulletin (PIT5429) was released on June 1st to deal with “vibrations” or “Rough Harsh Ride” for Yukon Denali, Cadillac Escalade, and Tahoe LTZ, Suburban LTZ models built before 2/10/2015. These models have the Magnetic ride control Suspension (RPO Z95). My vehicle is not equipped with this, but it might be useful for someone. Please see attachment for the bulletin.

this bulletin sounds like the problem everyone's been talking about. But why jus those models? Other than the harsh ride which I heard denalis gets

Posted (edited)

CI Houn - I have been commenting on this thread since page 1 and have read all 71 pages. According to data on this thread, two most frequent common denominators of the shaking, vibration, buffeting, and pressure (SVBP) in the GM fullsize SUVs was the extra length (EL) versus the standard length (SL) and the Magnetic Ride Suspension (MRS) versus the Premium Ride Suspension (PRS). But the most frequent common denominator, MRS, which is a standard feature in the Denali, Escalade, Tahoe and Suburban LTZs.

 

There are problems with the SL with PRS, but data on this thread along with this Tech Bulletin suggest you will have more problems with SVBP with the EL and MRS.

Edited by The Zip
Posted

It's ALMOST comical at this point. If you go back and read my posts from Dec of last year, when GM bought back our 2015 SLT Yukon and I bought the Escalade. I've said all along its the SHOCKS!

If the dip shit field engineer would come out to our house he could experience what happens everyday on my 30 foot driveway. We have a weird rain gutter rolling curb. When backing out you have too go off at a angle or you'll drag the front air dam on it. When the front wheel drops off, the wheel shoots to its full shock drop out with absolutely no rebound control. The suspension is a complete JOKE! It rides like a Shermin Tank! Their is NO doubt in my mind the suspension is a leading cause of this problem.

Posted

Reading through the Tech Bulletin posted by Cleanfreak, GM advertises a Magnetic Ride Suspension fix for builds prior to Feb 2015, however, the fix updates and reprograms the rear suspension but only replaces the front. No updates on the front won't change the performance of the component. Even if they happen to get the suspension spot-on, the Tech Bulletin specifically states it will not eliminate disturbances with the tire/wheel, propshaft, and rear axle. Technicians would have to refer to Tech Bulletin 1354 for those answers.

 

So to sum it up the Shaking and Vibration piece, GM appears to have updated MRS REAR components for builds after Feb 2015. At this rate of progress (if you want to call it that), a new generation will be out before all this is sorted out. At least GM is beginning to acknowledge their fullsize SUV Quality Control Senior Managers need to be fired.

Posted

Reading through the Tech Bulletin posted by Cleanfreak, GM advertises a Magnetic Ride Suspension fix for builds prior to Feb 2015, however, the fix updates and reprograms the rear suspension but only replaces the front. No updates on the front won't change the performance of the component. Even if they happen to get the suspension spot-on, the Tech Bulletin specifically states it will not eliminate disturbances with the tire/wheel, propshaft, and rear axle. Technicians would have to refer to Tech Bulletin 1354 for those answers.So to sum it up the Shaking and Vibration piece, GM appears to have updated MRS REAR components for builds after Feb 2015. At this rate of progress (if you want to call it that), a new generation will be out before all this is sorted out. At least GM is beginning to acknowledge their fullsize SUV Quality Control Senior Managers need to be fired.

On another forum someone replaced his Denali shocks with escalade shocks in the front and that improved the ride comfort. But not the vibration as far as I know

Posted

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!

Posted

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.

 

When you say active ride control, are you referring to active noise cancellation? Also, wouldn't you say that the differences in the GM fullsize SUVs are basically lights, grilles, and interior. You know, general aesthetic stuff. You can also throw in a bigger engine on some. But for the most part the frame, body mounts, chassis are the same. How is it accounted for that some trucks are having this issue and some are not; maybe its the combination of a larger wheel size, larger engine size, larger vehicle size, and magnetic ride control. These things in combination as opposed to individually may be having a negative ride impact on the fullsize SUV line. Use my truck combination for example, I have 20" wheels, the 355 hp engine, the standard length truck, and Premium Ride suspension and my truck has been driving issue free since Mar 2014, why? Since most of the trucks with Magnetic Ride has the combination, an upgrade by softening the suspension may be a positive first step.

Posted

When you say active ride control, are you referring to active noise cancellation? Also, wouldn't you say that the differences in the GM fullsize SUVs are basically lights, grilles, and interior. You know, general aesthetic stuff. You can also throw in a bigger engine on some. But for the most part the frame, body mounts, chassis are the same. How is it accounted for that some trucks are having this issue and some are not; maybe its the combination of a larger wheel size, larger engine size, larger vehicle size, and magnetic ride control. These things in combination as opposed to individually may be having a negative ride impact on the fullsize SUV line. Use my truck combination for example, I have 20" wheels, the 355 hp engine, the standard length truck, and Premium Ride suspension and my truck has been driving issue free since Mar 2014, why? Since most of the trucks with Magnetic Ride has the combination, an upgrade by softening the suspension may be a positive first step.

Issue free as far as what, the ride quality? Or both ride and vibration free?

Posted

When you say active ride control, are you referring to active noise cancellation?

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.

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