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  • 2 weeks later...

"I can see that happening especially on my truck. It seems to have good days and bad days. For instance yesterday it was pretty smooth as I drove it to the dealership. The only thing that is consistent is the vibration when cold. For the first 10 miles its very noticable I am being told that its the tires. The 50-40 mph vibration on deceleration is also pretty standard."

 

Your tag doesn't state whereabouts you live but if it's way up there in cold country I'm guessing that your "first 10 miles" problem is indeed caused by flat spots on your tires due to sitting overnight in the cold. In my opinion, vibration when decelerating is either caused by tire alignment or loose/worn front end geometry. However, being your truck is fairly new I would check into tire alignment first. Just me though.....

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  • 4 weeks later...

I am curious if anyone has gone through the vibration analysis and diagnostic process with their dealer. The information on the OEMDTC website states that the first order tire frequency range is 11-14 Hz.

 

I have the stock tire size (P275/55-20). Revolutions per mile = 652 from the manufacturer's website. The 1st order (Fundamental) frequency is 10.86 Hz (this is center frequency) so the guideline does not even encompass the center frequency. The pico-scope has a 0.1 Hz resolution based upon information I found on the internet for the GM product and a frequency range of 0-350 Hz.

 

The diagnostic guide references everything to 60 mph, but never explicitly tells the mechanic to operate at 60 mph. In fact, the first diagnostic complaint is vibration at 60-70 mph. If it occurs at 65 mph on a truck, but not at 60 mph then you get "Cannot duplicate customer concern" because the truck was never operated at the speed causing the vibration. A vibration at 40 mph (35-45 mph region) has a fundamental frequency of 7.2 Hz.

 

I took a few measurements on the rear seat frame with the following results: 8 Hz (all measured speeds 65, 64, 63, 60, 41 and 30 mph), 11 Hz at 41 mph and 12 Hz (65, 64, 63, 60 and 30 mph) stand out on the graph. Also, I have a couple of dominant frequencies around 107 Hz and 180 Hz for all speeds. My frequencies were pulled off a printout and rounded off. However, the equipment that I used is more accurate than the dealer's pico-scope with a significantly higher sample rate and frequency resolution.

 

I calculated a fundamental frequency of 33.9-43.0 Hz (3.08 rear end) and 37.6 - 47.9 Hz (3.42 rear end) using the diagnostic guides listed tire fundamental range of 11-14 Hz. The diagnostic guide states the range for the prop shaft is 38 - 44 Hz. Is my math wrong or am I missing something?

Edited by GMCSierra4x4
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I am on a Mac book and can can not get the link to work. Do you have another link? Just got my new 2014 and have noticed this issue as well. Mine has the 20 inch wheels on it. Thanks

Edited by mr8ball
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  • 3 months later...

Hi I bought a Preowned 2014 GMC Sierra last night I noticed some vibration and decided to look it up online.

I already talked to the dealer and I am bringing the truck for an inspection. Could you please send me a copy of that bulletin the link doesnt work for me.

Thank you

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  • 2 weeks later...

got mine back last week brought it in for a whole list of issues one of them being vibration they found 2 of the rear tires to have excessive road force. then they used a peco meter to see if the vibrations went away for the most part they seem to have disappeared but i don't do a lot of highway so time will tell. tires are the good year wranglers sr-a. i also just notice i paid an extra 125 to have all terrain tires on my truck according to my window sticker and the wrangler sr-a are not all terain tires they are all season highway tires im not happy with this whole experience with this truck GM really sucks. . .

Edited by scottl1346
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  • 4 months later...

Information on Vibration Analysis and Diagnostic 2014/2015 Chevrolet Silverado and GMC Sierra

 

 

This seems to be a vibration campaign that has been around since January 2015. I have seen many complaints on different forums about this issue. I also have a vibration/harmonics issue that is not there all of the time but most. My issue seems to be centered around the V4 decel, and body mount configuration. This link is filled with a ton of information about various causes and repairs many of the 2014/2015 GM truck owners are experiencing. Some may be experiencing a combination of more than one issue at a time. Many more may not be experiencing any vibration at all. I do believe for those folks with the "Cadillac ride" its only a matter of time before they start experiencing vibration/harmonics issues. Its kinda nice to get this information out so that GM can streamline the repair process even further. If enough of these trucks show up for repair request for vibration they may even send out letters to further enhance quality control.

 

http://oemdtc.com/6392/information-on-vibration-analysis-and-diagnostic-2014-2015-chevrolet-silverado-gmc-sierra/3

 

If link does not work copy and past in your browser.

It's a dead link these days.

 

 

Sent from my iPad using Tapatalk

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Have a 2015 Sierra, 5.3 engine, crew cab, 5'9" bed. I have lowered it with drop spindle kit and bell tech shocks, cold air kit, and flow master cat back. Have also installed a super chip. Have had a vibration since I got the truck but thought it may be air turbulence since I had to cut the front spoiler about 3". Anyway on Thursday 17 Nov I decided enough of this vibration stuff. I decided to drive through it as it came and went about 50 ish, I just kept pushing and about 93 it came in again and got worse up to about 98 so I started backing off and it blew at about 92 mph. No problems getting down to a stop place. First called a wrecker, then uninstalled the super chip. The drive shaft looked like it had been cut off with a hacksaw, That little thin aluminum tube packed with cardboard shouldn't even be on a truck. The service dpt told me that it would take 500hp, show me. Anyway warranty is going to cover it and any consequential damages. I wanted a aftermarket steel driveshaft, about $350.00 but they talked me into taking another stock one and if it vibrated they would give me free installation on an aftermarket unit. It should be ready on Tuesday. We will see and I will keep you informed.

 

The old man (76 comin 77)

 

Richard

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Have a 2015 Sierra, 5.3 engine, crew cab, 5'9" bed. I have lowered it with drop spindle kit and bell tech shocks, cold air kit, and flow master cat back. Have also installed a super chip. Have had a vibration since I got the truck but thought it may be air turbulence since I had to cut the front spoiler about 3". Anyway on Thursday 17 Nov I decided enough of this vibration stuff. I decided to drive through it as it came and went about 50 ish, I just kept pushing and about 93 it came in again and got worse up to about 98 so I started backing off and it blew at about 92 mph. No problems getting down to a stop place. First called a wrecker, then uninstalled the super chip. The drive shaft looked like it had been cut off with a hacksaw, That little thin aluminum tube packed with cardboard shouldn't even be on a truck. The service dpt told me that it would take 500hp, show me. Anyway warranty is going to cover it and any consequential damages. I wanted a aftermarket steel driveshaft, about $350.00 but they talked me into taking another stock one and if it vibrated they would give me free installation on an aftermarket unit. It should be ready on Tuesday. We will see and I will keep you informed.

 

The old man (76 comin 77)

 

Richard

Packed with cardboard, can you get pictures? If the drive shafts are filled with sound deadening material is it slipping or moving causing driveshaft unbalance????

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Link didn't work for me either. Just got a 2015 6.2 with the 8 speed and 10k miles. Seems like there are at least a few things causing different types of vibration. Mine was only after the truck warmed up and rhythmic vibration in the steering wheel between 45 and 70 but only at constant speed not accelerating or decelerating. Took it to the dealer on Monday. They ordered a torque converter which was installed yesterday. Smooth as silk now and the truck shifts a lot smoother as well. So anyone with the vibration I described should start with replacing the converter. As for all the people who said trucks vibrate so get used to it....I don't think so. This is my 5th truck and none of them have had a vibration like this. Also, I couldn't be happier with my local dealer. They listened to what I said and didn't jack around with tire balancing or any other petty stuff

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