67Motorcat

Going out on a limb here,

But my reasoning has some basis and I have solved these types of vibration issues in the past on several engine swap "Hot Rods" projects.

I am no engineer,but I understand a few basic rotational principles.I find it unsettling the GM brass has not tried this:

(1) Truck are designed to carry weight.Differences in models,ext cab,crew cab,4WD,short bed,long bed,spring and shock rates etc, or any combination of all account for many,many differences in ride height.

In fact 2 identical trucks can vary in unloaded ride height.

(2) I am assuming that all 1/2 ton trucks,for example,except the 6.2 1/2 ton,are running the same production rear axle assembly.Gear ratios may vary but not relevant here.

(3) Also assuming long beds and /or crew-ext cab are running a carrier bearing and 2 piece drive shaft, while short beds running a single.

(4) Assuming the all above combination all have the rear leaf spring mounting pads welded identically,usually at about 3* positive,regardless of what model configuration it is going into on the assembly line.

You see where I'm going with this .....Have the dealer put around 500 lbs in the bed of the truck and test drive.If the vibration goes away or diminishes significantly,Bingo.....

The driveline angles are out of phase....the weight added to the bed changes the angle and cancels it out.This is a simplified explanation as to why this happens,but with the super stiff frames of the new 2014 models there is no hiding this slight out of phase issue.The shaft whip is easily felt.

All the speeds at which everyone describes also fits this issue verbatim.It would be interesting to see which combo model is experiencing the most issues.I would guess models with the one piece driveshaft,but also could be short bed ext. cabs,highest first angle.

It also explains why some models have the issue and other do not based on all the different combos available.Even optional equipment(weight changes) can effect the static driveline angles at rest.

This would be a hard pill to swallow for GM.There is no way they would allow to have a different part number for rear axle assemblies based on varying axle pad locations.....but what do I know....

See what they say and let us Know.

I personally have a new 2013 2500 HD ext cab short bed,but guess what,A 4" diameter aluminum 1 piece beef of a drive shaft.They were thinking on that one.My 200K mile plus 99 1500 has a 2 piece and is always butter smooth

Desert SS

This site is ONLY about the vibration problems. The site asks for year model, cab style, gear ratio, 2wd or 4wd, length of cab, miles, at which miles it vibrates, make model of tires, aftermarket accessories so we can get a bead of what is really going on.



www.gmtruckvibes.com

jorr101

A coworker of mine has a 14 he was having this issue on the dealer put a driveshaft on it. He said it made it 99% better but it didn't go completely away.

jk2jksr

FYI: I have purchased a CPO 2014 Chevy Suburban with 28,000 Miles on or about November 13, 2014. 4WD. As far as what type of tires and wheels, it does not matter. The dealer service "foreman" had tried the stock tires that I had owned and the new 22 inch Bridgestone w/aftermarket wheels - with same results. The results I am trying to convey it to the world is that on or about 39 MPH, in accelearation, there is a loud vibration that ends at 50 MPH. And, same in decelration from 49 MPH to 39 MPH. To clarify type of vibration if I may be able to decribe; it is a vibration for sure, yet it sounds like a I am going thru a wind tunnel. No rattling, no additional vibrations to anywhere else. Just an enormous vibrations. Initial visit after the Thanksgiving, the dealer tried very hard to ignore it. Y'all know how it is........."it is typical sound of a Suburban," after doing nothing for the 3-4 days. So, I took it back and had service foreman ride with me........then, he had acknowldged that there is a enormous vibrations. So forth, he took it in for 10 days, and I had received a call to p/u my vehicle. Shoot, I was so elated that I had even expensed $200 on other needs non related to the vibrations. Heck, after 5 minutes out of the dealer, same old vibrations again. When I had called service dept., very strange reactions. Don't bring the vehicle back today, bring it back in few days when a Manager of service dept. to have it look. The service manager calls and says that this is to be escalated. Now, no test drives or anything in that nature. He says that he will need to get hold of GM and have a field engineer fly out to diagnoise the situation and it will take few days. After few days, I took the vehicle in on my own to keep everything up and up. The manager says that the field engineer is very hard to get hold of, yet they will replace the entire drive train. After another 7 days, I get a call to pick up my vehicle. Funny, the service rep is in a hurry to get my butt out of the door. He says, everyrhing is in that invoice. I look at it, all they have done was replace the shaft and states that they had test drove for 50 miles and it was fixed. After pulling out of the dealer, same old vibrations again. So, I take it back, and argued like bat out of hell..............again, silence. The official reply to my compalint was......."oh, we had tried everything, we will have the field engineer take a look at it....................!" They gave me a loaner..........it has been at the dealer since. Now, tomrrow.........at 12:00............I am suppose to get my vehicle back. Let's find out how goes.


PS...Desert SS.....I am not an expert in automobile....so forth, please hang with me in my brief explanations. It is not very technical explanations. Sorry!


jk2jksr

jk2jksr

Yeah............I am getting my vehicle back tomorrow at 12:00 Noon. Let's find out how it goes. They have adv. that they will replace the differential.....tried the rear shaft, bearings............and some other things.


By the way, following are my current situations I had shared with Desert SS:
FYI: I have purchased a CPO 2014 Chevy Suburban with 28,000 Miles on or about November 13, 2014. 4WD. As far as what type of tires and wheels, it does not matter. The dealer service "foreman" had tried the stock tires that I had owned and the new 22 inch Bridgestone w/aftermarket wheels - with same results. The results I am trying to convey it to the world is that on or about 39 MPH, in accelearation, there is a loud vibration that ends at 50 MPH. And, same in decelration from 49 MPH to 39 MPH. To clarify type of vibration if I may be able to decribe; it is a vibration for sure, yet it sounds like a I am going thru a wind tunnel. No rattling, no additional vibrations to anywhere else. Just an enormous vibrations. Initial visit after the Thanksgiving, the dealer tried very hard to ignore it. Y'all know how it is........."it is typical sound of a Suburban," after doing nothing for the 3-4 days. So, I took it back and had service foreman ride with me........then, he had acknowldged that there is a enormous vibrations. So forth, he took it in for 10 days, and I had received a call to p/u my vehicle. Shoot, I was so elated that I had even expensed $200 on other needs non related to the vibrations. Heck, after 5 minutes out of the dealer, same old vibrations again. When I had called service dept., very strange reactions. Don't bring the vehicle back today, bring it back in few days when a Manager of service dept. to have it look. The service manager calls and says that this is to be escalated. Now, no test drives or anything in that nature. He says that he will need to get hold of GM and have a field engineer fly out to diagnoise the situation and it will take few days. After few days, I took the vehicle in on my own to keep everything up and up. The manager says that the field engineer is very hard to get hold of, yet they will replace the entire drive train. After another 7 days, I get a call to pick up my vehicle. Funny, the service rep is in a hurry to get my butt out of the door. He says, everyrhing is in that invoice. I look at it, all they have done was replace the shaft and states that they had test drove for 50 miles and it was fixed. After pulling out of the dealer, same old vibrations again. So, I take it back, and argued like bat out of hell..............again, silence. The official reply to my compalint was......."oh, we had tried everything, we will have the field engineer take a look at it....................!" They gave me a loaner..........it has been at the dealer since. Now, tomrrow.........at 12:00............I am suppose to get my vehicle back. Let's find out how goes.


PS...Desert SS.....I am not an expert in automobile....so forth, please hang with me in my brief explanations. It is not very technical explanations. Sorry!


jk2jksr

67Motorcat

The above description furthers my belief of driveline angles being out of phase.


Upon acceleration the pinion angles slightly upward until cruising, then settles to neutral.


Upon deceleration the pinion angles slightly down until engine braking is not enough to have an effect.


The new models also have softer spring rates on the top leaves, so ride is improved when not carrying any weight, this further contributes to the issue.
As the springs are more susceptible to twist without much torque.


Both can result in vibrations....If I were a betting man, I would bet GM has got to know about this. They just don't know what to do now.

Desert SS

Not a problem
Were all after the same goal !

Desert SS

I'll agree with you 67Motorcat

After all they are just pickups not Space shuttles

GM's Engineering Division has a ton of explaining to do !

jk2jksr

Thanks.........the dealer gave up, or you might be right. GM does not know what to do with it. They gave up as of yesterday. They are going to take back the vehicle. Thanks............for your support.


jk2jksr

TooByFoor

Consider yourself lucky. My dealer, Jim Trenary Chevrolet in O'Fallon MO just "gave up". They told me to call GM (yea, those friendly GM Support reps that chime in on these forums), who then told me they'd call the dealer to work it out , and once they collaborated they all just said "It's normal". Actually, the GM rep just kept reading from her screen how sorry they were, until I eventually hung up.

So, there's a black 2014 Silverado Z71 Crew Cab with 3,000 miles on some poor dealer's used car lot somewhere, and even though I took a bit of a loss, I couldn't be happier in my 2015 Ram.