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Aboothlsu

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  1. Aboothlsu
    There are several different issues in this thread. A lot of it is typical things that will cause any vehicle to vibrate like bad/poorly balanced tires and driveshafts, things that aren't specific to these trucks. I would say a lot of what is in this thread falls into those categories. Then there are more complex issues that are directly related to the design, manufacture and assembly of the trucks and specific parts. Everyone is not experiencing the same thing
  2. Aboothlsu
    Drive shaft deflection is a very hard pill to swallow. Critical speeds and deflections of rotating shafts are straightforward to estimate and design a shaft correctly. Any GM design engineer worth his salt should have a good handle on this and not to mention years of successful driveshaft designs to pull from. Also the shafts would be designed for the top speed of the truck plus a SF probably 25% minimum. Much faster than you would be driving it.
  3. Aboothlsu
    I wish I wouldn't have tipped my hand with the lemon law thing. I think they are blowing smoke at this point because they are running out of things to replace. Its been so long since Ive driven my truck Im going to have a hard time remembering how bad it was vibrating and if its any better when I finally do get it back. I may call tomorrow and see if they have started replacing the exhaust yet. Ask if I can take it for a drive just before so I can see if there is truly an improvement.
  4. Aboothlsu
    Did he say why he replaced the exhaust, and if it was a different design?
  5. Aboothlsu
    Ive had 3 different drive shafts on mine, 2 different designs with no change. Both the original smaller design and the more stout design Im guessing aluminum.
  6. Aboothlsu
    Im curious to see what the fix was as well. Just about every part in the driveline of mine has been replaced. It has been 30+ days in the shop so I opened a case with GM Tuesday to get my ducks in a row to fight for a buy back. The same day the GM field engineer told them to lock open the flapper in the exhaust due to it causing vibration in a few other cases. GM contacted the dealership Wednesday about my complaint and the sales manager called me. I told him we were getting into lemon law territory and I was tired of the tinkering on my truck and didnt even want it back at this point. Coincidentally later that day the service manager calls me and says locking the flapper open fixed the issue and they are ordering me a new exhaust system now with a redesigned flapper. Should be in today or tomorrow. I am very skeptical if this fixed it or now they feel a sense of urgency to get my truck out of there before they are forced to buy it back.
  7. Aboothlsu
    It is plausible that it could create vibration, if its not opening properly or sticking, pressure could build slightly on the other side until it flaps open. Creating a sort of pulsing or surging as the pressure builds and is released repeatedly. That being said I am still a bit skeptical this is the smoking gun. Im going to check the loaner truck i have and see if i can lock it open when i get home. That truck is a train wreck with the shimmies and shakes.
  8. Aboothlsu
    Dont jump the gun on that purchase just yet. This is really the first time this flapper has been linked to the vibration issue that I can tell. It may solve some, or maybe none at all. I havent driven my truck to see for myself if this fixes it Im only going by what the service manager said. There shouldnt be a fuse, it looks to be purely mechanincal and spring loaded, there should be square ends outside of the exhust pipe that you can use to rotate the flapper open. Put a hose clamp on the square end and lock it in place. I personally havent tried this, b/c I first learned of this flapper yesterday, but looking at the thread on the flapper and pictures it looks pretty straightforward.
  9. Aboothlsu
    If anyone still has there truck available apparently it can be locked open with hose clamps pretty easily. It would be nice to see someone try it and see if it improves things.
  10. Aboothlsu
    High speed mostly, but a slight vibration always seemed to be there. I also could hear a slight whine like gears were out of tolerance or something at 70+, but it couldve been this flapper rattling around. Digging thorugh the thread on this thing, people are locking it open or removing it all together because they can hear it rattling or to make their exhaust sound better. The only purpose Ive seen for it is for acoustics in V4 mode at highway speeds. I'm having the service manager find out what its for and if they can remove it.
  11. Aboothlsu
    Heres a new one for everybody. I've read through this entire thread and have never seen this mentioned. The dealer locked open the "flapper" in the exhaust and drove it said the vibration was completely gone. Unlocked it and drove it home and vinration was back and even worse. They said that it was definitely the problem and they ordered me a new exhaust assembly. I have no idea what this flapper is for and the first I heard of it was yesterday when they were going to test it. The service manager isnt even 100% sure what it is for and thinks it has to do with the AFM. http://www.gm-trucks.com/forums/topic/153020-exhaust-adaptive-valve/ Im not sure if this thing is required or not, Im wondering if I should just tell them scrap that order and go aftermarket exhaust with no flapper.
  12. Aboothlsu
    Yeh I forgot to mention another fact This reminded me I forgot to mention my loaner truck. The one in the shop is a 2014 GMC Z71 4x4 SLT. The loaner is a 2014 V6 SLE. The loaner has convinced me to not ask for a replacement. It shakes just as bad if not worse than mine at all speeds. Also theres some other random gremlins, the radio display froze with only a corner of the screen lit up for a day, the knobs did nothing, but the steering wheel controls controlled the radio and the radio still worked. Then the next day when i got in everything was fine. Also the AC randomly changes speeds without me touching it. I can be driving all day then all of a sudden it kicks up or down a notch.
  13. Aboothlsu
    has anyone had any luck with the lemon law. Here is part of it in my state. Manufacturer's ResponsibilityUnder the Louisiana Lemon Law, the vehicle's manufacturer or the authorized dealer must either repair or replace the vehicle. After the manufacturer or dealer has made 4 attempts to repair the vehicle, or the vehicle has been inoperable for 45 days due to repairs, the vehicle must be replaced or refunded. The problem must be resolved within 10 business days. Im not sure if I already qaulify under this law, more than 4 attempts have been made but all during the same shop stay. So not sure if all of this counts as one attempt or multiple. Ive been waiting for that 45 day mark to demand a refund or replacement.
  14. Aboothlsu
    At this point to be honest Im hoping they dont find it and they buy it back. I really dont want to swap it for another truck and go through all of this again in a few thousand miles. Or them finding a solution that temporaily reduces the vibration and Im back in there in a few weeks. After they try experimenting with the exhuast Im afraid they are going to start tinkering in the transmission and torque converter. I'm tired of GM running experiments on my new truck.
  15. Aboothlsu
    Update on mine. 30 days in the shop, still no resolution. Things theyve tried Tires all rebalanced and road forced multiple times. Swapped tires and rims with other trucks. Driveshaft replaced with other truck on the lot. New design driveshaft ordered and installed. New Rear end assembly ordered and installed. All motor and trans mounts checked and replaced. Specialty tools were overnighted to check all driveline angles. Now they are opening some valve in the exhaust manually and taking it for a test drive to see if it is getting stuck closed causing the vibration. I want them to buy it back from me at this point. I dont want to drive a science experiment frankestein truck now even if they do fix it. I believe eventually they will find some way to minimize it and give it back to me claiming it is now within spec. Who knows what else the vibration has effected causing a premature failure down the road. I want them to buy it back not replace it. I've been a loyal gmc fan and love everything else about the truck but dont want to risk another lemon.
  16. Aboothlsu
    Well finally my rear end assembly came in after 2 weeks. Installed and the techs said there was no change to the vibration and they are back at square 1. This coming Tuesday makes 30 days in the shop. Next they plan to put to use some sort of vibration tool and see if its possibly in the torque converter or transmission. At this point I believe its something inherent in the design of the truck and its components, maybe even the frame itself. The new frame design or perhaps another major component may have a natural frequency that is too close to the vibrations caused by the engine at certain speeds/rpm combinations causing small vibrations by the motor to be amplified into something more noticeable. They can continue replacing parts and may reduce it somewhat but wont correct it. No 2 trucks will be exactly identical and It may be minimized from one truck to another depending on the tolerances, assembly methods, batches of parts etc but it will still be there and over time potentially get worse as parts wear down, temps and fit of parts slightly change. It will take a design change to truly correct it.
  17. Aboothlsu
    same thing they were told to check before ordering mine. Apparently it was out of spec
  18. Aboothlsu
    The dealership has been fantastic to this point and said that they will not give it back to me until it's fixed. I'm hoping this means a new truck or refund if they can't fix it. If not lemon law and an F250. i hope ot doesnt come to tbat point.
  19. Aboothlsu
    My rear end is on the way. Should be in today or tomorrow. Trucks been in the shop 10 days and counting. Hopefully this fixes the problem.
  20. Aboothlsu
    Trucks currently at the dealer. I don't remember what it is offhand. I have to call them and have them take a look. I've also finally read through this entire thread and it seems a lot of people have went through multiple tire changes, balancings etc. some fixing the problems, others no luck. I'm not sure why the dealer hasn't even explored this option only relying on the fact they rebalanced all the tires on mine over a month or so ago when I first came in for the vibration issue. I'm not sure the tires have ever been road force balanced and I haven't received any new tires. I'm not sure they have even considered either of these options before jumping to trying new driveshafts and now a complete rear end assembly. If they have they haven't mentioned it to me. Is it possible that a bad set of tires, not properly balanced, or road force balanced, or this combined with the vibration issues caused the blowout. The tire lost all pressure instantly due to a tear in the sidewall coming around a sharp 180 degree turn when switching interstates on the highway, when there was high lateral loads. I've asked this question and they claimed it was in no way related.
  21. Aboothlsu
    Im not sure the exact build date, I bought it around oct 2013 so its one of the earlier ones. I will try an find that out and will post it here.
  22. Aboothlsu
    It's hardly at random. The driveshaft issue is something they have already seen a few times and well know enough at gm that the design has already been changed. They have also done most of the things you mentioned. Inspected all the gears, bearings, ujoints, checked for tolerance issues in the gears and the contact pattern. Inspected and checked tolerances on both drive shafts and everything looked normal. Replacing the entire rear end was a decision made outside of the dealership by whomever at gm they contact for advice.
  23. Aboothlsu
    I haven't read through all of 70 pages of this thread but ill share what's going on with mine. I have a 2014 gmc z71 4x4 slt short box. At this point I have around 13000 miles. Over time ive been getting more and more unhappy with the ride. It seemed louder inside the cab with a slight vibration I could feel through the pedal when accelerating and through the seat and slight rattles inside the cab started to develop. I brought it in to the dealer and had all 4 tires rebalanced. They found one tire was slightly out of balance and I went on my way thinking I've found the problem. Well the same issues were still there, I wasn't sure if it was just typical issues that develop as the truck was getting used or just in my head. Other things I started to notice when its wet my rear leaf springs or something in the rear started squeaking like an old mattress when going over bumps at slow speeds, backing out of the driveway etc. I had an oil change coming up soon so I was waiting to bring it up when I brought it in for that. The a few days ago I had a right rear blowout on the interstate, nothing punctured the tire, there was just a tear in the sidewall. I brought it to the dealer at this point to gt a tire and explained all the other issues afraid they would just say it all was normal and send me on my way with a vibrating squeaky rattling truck I would just have to live with. Well it wasn't the case, the techs noticed the vibration and said in no way is the noise in the cab or vibration normal. They said they have had a few others that the problem was in the driveshaft and swapping it out fixed the problem. So they took a driveshaft of another truck on the lot and swapped mine, didn't fix the problem. Gm said they have a redesigned driveshaft b/c of these problems and possibly the one on the lot was the old design. They ordered the new driveshaft design swapped mine and it didn't fix the problem. They told me a tech recently came back from training, and there was a case talked about at another dealership where the entire rear end of the truck had to be replaced to fix a vibration problem. Axel, differential driveshaft, etc. basically everything between the rear tires. Apparently something in rear end was out of tolerance. That's where I am at now. They are ordering me a complete rear end assembly. Hopefully it will be in next week and will fix the problems, if not I don't know what will happen.

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