Shake or Vibration Issues

JT-IN-BAKO-CA · May 8, 2014

well I hope that fixes 99% of the peoples problems. that makes it 10x easier to make my purchase

can you give us a little more information as to how you lock it open or remove it? is it as easy as removing a fuse in the main fuse box called flapper? sorry stupid question but I don't have the truck yet hard to visualize lol going out of town to pick it up this weekend

Edited May 8, 2014 by JT-IN-BAKO-CA

hotrodz37 · May 8, 2014

Page 5 of this thread. when the truck is off, the flapper will be closed. twist the square piece til it opens and clamp it open with a lager hose clamp. If it works great, then cut that thing outta there! I will give it a shot this weekend and report on the findings!

http://www.gm-trucks.com/forums/topic/153020-exhaust-adaptive-valve/page-5

Aboothlsu · May 8, 2014

well I hope that fixes 99% of the peoples problems. that makes it 10x easier to make my purchase

can you give us a little more information as to how you lock it open or remove it? is it as easy as removing a fuse in the main fuse box called flapper? sorry stupid question but I don't have the truck yet hard to visualize lol going out of town to pick it up this weekend

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.

Edited May 8, 2014 by Aboothlsu

MJFlores · May 8, 2014

This flapper seems hard to believe, but it's worth a shot. My vibration at HW speeds gets worse as the truck goes a while and warms up all the way thats for sure. I also feel the vibration in the floor and gas petal the most. Ya know...certainly could be that damn thing. Mine is going in tomorrow am, so I'll mention it as something I read. For what it's worth...I really like this new truck...and I mean everything about it. However, this whole vibration this is a HUGE deal braker for me. I will be thrilled if it's that stupid flap...with how easy it is to lock open with wire or a hose clamp. I'm anxios to hear from people who have pulled their exhaust and swapped to aftermarket...can anyone confirm this isn't an issue on thsoe trucks?

Aboothlsu · May 8, 2014

This flapper seems hard to believe, but it's worth a shot. My vibration at HW speeds gets worse as the truck goes a while and warms up all the way thats for sure. I also feel the vibration in the floor and gas petal the most. Ya know...certainly could be that damn thing. Mine is going in tomorrow am, so I'll mention it as something I read. For what it's worth...I really like this new truck...and I mean everything about it. However, this whole vibration this is a HUGE deal braker for me. I will be thrilled if it's that stupid flap...with how easy it is to lock open with wire or a hose clamp. I'm anxios to hear from people who have pulled their exhaust and swapped to aftermarket...can anyone confirm this isn't an issue on thsoe trucks?

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.

Edited May 8, 2014 by Aboothlsu

20L8TSierra24 · May 8, 2014

For what its worth, I was under the truck and right where the rear u joint is, it appears it has slung some grease around on the undercarriage. Not much, but defective u joints can cause major problems as well. . .Food for thought...

hotrodz37 · May 8, 2014

I have read through all 93 pages and have been reading from the get go, but can't for the life of me remember if anyone has chimed in here. Does anyone have this issue with the 3.08 rear end? I have the 3.42 as I think most of us do. My buddy has a 2014 with the 3.08 and his is as smooth as silk at all speeds.

Silverado 6.2 · May 8, 2014

For what it's worth, I bought the Range device that keeps the engine locked into V8 mode. I've had it for about 3 weeks and so far I have had no vibration. Now this could just be coincidence as the vibration seems to be random at best on "this" truck. But so far so good. Does anyone know if the torque converter act any differently or could it, if the vehicle is in V8 vs V4 mode? One last thing I'll add: I love this device! No hiccup or hesitation when pushing slightly on the pedal. That AFM is crap! So far milage has went down a tenth MPG. (I didn't buy the truck for fuel milage anyway....)

I believe when the engine is in v4 the torque converter does not fully lock up, at least that's the way my 08 was, I haven paid attention to my 14 to see. I could tell by watching the rpm on the highway and when it when to v4 the rpms went up 150 or so and stayed that way until it went back to v8

tbarn · May 8, 2014

Mine has been bolted open for a couple thousand miles. Still vibrates.

pm26 · May 8, 2014

It is hard to link an exhaust flapper valve to mechanical vibration. Mechanical vibration results from badly machined, badly assembled, badly balanced, or badly aligned parts in the the driveline, or badly balanced wheels, brake rotors, or improperly assembled wheel hubs. A lot of possibilities, but that's what you get when the manufacturer scales back quality control or uses poorly trained personnel for assembly of components that require special skills (assembly of differentials, transmissions, balancing of critical driveline parts, etc). A penny saved is a dollar spent in this case.

Edited May 8, 2014 by pm26

Paicer · May 8, 2014

Are you pursuing the issue? You described exactly what I'm seeing. It's getting progressively worse, and I now feel it strongly in the gas pedal, floor, seat, and center console. I never felt it in the gas pedal until today and it was so bad it made my pant leg shake. Something is evry wrong with these trucks. Mine is going in on Friday am...if they try to feed me that line of bull (that it's normal) I'll be reporting that to GM. I'm going to remain optomistic that they'll do the right thing for their customer so lets see what happens. We shouldn't have to be going through this with new trucks.

Yes I am pursuing the issue, I'm not giving up until its either fixed or they give me back my money and take my business elsewhere. Though from the sounds of it, this other dealerships service manager is a good guy and agrees with me that its not normal at all. Said he will personally look over it. Though if its not fixed, you can count on GM getting a very quick call.

2strokesmoke · May 8, 2014

If anyone is following along here, I brought my truck up to 50mph set the cruise, quickly slipped transmission into neutral and turned off engine with key.

With the engine dead off and no load on driveshaft the vehicle continued to vibrate and shake with no change.

In conclusion that completely destroys the flapper as the culprit for the 40mph - 50mph speed related and 70mph fine vibration as well.

This brings we to a driveshaft parts issue, or bad torque converter, or torque converter lockup.

If the driveshaft ends up being out of balance, or having a bad runout!

Replacing the driveshaft (propeller shaft) as the fix would be the right step to fixing this issue, however all the parts from supplier would be bad as well.

This might be why there is a new part number issued for the driveshaft most recently.

This would mean that GM knows of this issue with driveshafts, but chose to deal with customers case by case instead of replacing 400,000 + driveshafts or issuing a tsb.

A "TSB" created means a big cost to GM 400,000 × $400 + dealer labour= no proplem

2strokesmoke · May 8, 2014

Please this sounds like the most pratical fix to date, and we do have 1 confirmed fix with the c clamps to driveshaft as of yet.

We should be demanding our dealership to have our driveshafts balanced independently first, before any other action!!!!!!

This will prove that the driveshaft is indeed out of spec right from the factory, and any replacing of the driveshafts through warranty must be confirmed by factory tested and confirmed parts.

Machine welded driveshafts, means thousands of out of spec driveshafts, and absolutely no qualified quality control being done at the manufacturing level.

This my friend is what upsets me the most! A good truck, with cheap parts, and untrained associates, and a failed quality control system will destroy GM's legacy wait and see.

I hope some big wig at GM is reading this and wakes up with swift changes!

beetle · May 9, 2014

I have read through all 93 pages and have been reading from the get go, but can't for the life of me remember if anyone has chimed in here. Does anyone have this issue with the 3.08 rear end? I have the 3.42 as I think most of us do. My buddy has a 2014 with the 3.08 and his is as smooth as silk at all speeds.

3.08 on mine and smooooth.

Boughtalemon · May 9, 2014

So I dropped my truck off last night at the dealership. The service manager calls me and leaves a voicemail at 7:30 tonight and says the GM Engineer had been working on it all day and it is fixed. Im not very optimistic but I'll report back tomorrow.