Shake or Vibration Issues

[abominable z71]

Abominable, were you the person that was going to look for someone to balance the wheel on the truck so that hub and rotor were factored in?

If so, what were your results?

Yeah, I had the tires trued and balanced on the truck, it helped out quite a bit but there's still a vibration starts at 72 peaks at 76 and is gone around 80. It's pretty mild compared to some I've seen and if it was this mild from the start I might have never noticed it but now I know exactly what to look for. It's like a small door ding you only see from a certain angle but once you find it you can't help but notice it.

[Wrench589]

I have a steering wheel shimmy.

 

Last question for the crew, will a worn shock or one that loses its ability to dampen cause a tire to have excessive bounce. I think the answer is yes but:

Would it feel like an out of balance tire even though it might just be road undulations?

 

Coil springs on the front will pick up a natural resonance, some springs actually have weights attached to break up the resonance. If my shocks are worn (36000 miles but not leaking), it may not be able to stop the spring resonance by applying the forces against the spring.

 

I have a stretch of road in town that has manhole covers placed in the section where my right tire hits them.

It feels like the front end stutters over everyone.

 

I drive the exact same stretch of highway daily and to be honest some days are completely different than others with the handling

I see on this forum some of our members are finding CV joints in the front with too much play. Will that cause a front steering wheel vibration?

You know, my Yukon has this "unsettled" shake/shimmy whenever going over a bump. Wouldn't call it a steering wheel shake, more of an overall body jiggle. But the comment about excessive play in the CV joints struck a chord when I read it. That's what it feels like. Something worn or loose. CV joint, or suspension bushing or ball joint. Something like that.

 

I wonder if there is something like that going on here??

[DALaws]

I know it's difficult and time consuming to go through this whole thread. Bottom line is, Road Force Balancing helps many trucks reduce the vibration significantly, but does not eliminate it completely. From what I have read from this entire thread , GM has yet to identify, or care to divulge the source of vibration. Most dealers have tried unsuccessfully to eliminate the vibration and often times spend much time and money to remedy. In my case, they refuse to look at truck any further because they have "been down this road" before without success and support from GM. I think GM dealers are as frustrated as us unfortunate owner's of "shaker's".

 

I think some posts in this thread are mixing the V4 shake with the shake/vibration at speed. They are two independent issues, and this thread is intended to express vibrations of trucks at speed. it appears the 'shaker's" at speed there is no known "fix' or any definitive cause. There has been many, many speculations concerning the "fix", but most are unsubstantiated and not approved by GM.

 

I can't begin to express how disappointed I am with my truck vibration as with many on this thread. I am so disappointed and frustrated with GM. I find it hard to believe they do not know what the problem is. I have to think they do, but it is not safety related or affects the vast majority of trucks they sell. As it was told many years ago..,"just follow the money" and you will likely find their motivations. In this case, why would GM want to publicize that some of their trucks have some inherent defect which cause some of their trucks to vibrate? Answer- bad publicity which may mean less sales, less profit. I think this issues is a simple as that.

[tnchevy]

I am quite positive that GM knows what the source of the vibrations are. They have all kinds of engineers and you know that at least a few are smart enough to pinpoint the problem. The issue to me is that they know what the problem is but it will cost them more money than they are willing to let go of to fix them. As I mentioned before, there will not be a legitimate fix from GM for the problem and they will eventually engineer it out of future models.

[dave07]

I am quite positive that GM knows what the source of the vibrations are. They have all kinds of engineers and you know that at least a few are smart enough to pinpoint the problem. The issue to me is that they know what the problem is but it will cost them more money than they are willing to let go of to fix them. As I mentioned before, there will not be a legitimate fix from GM for the problem and they will eventually engineer it out of future models.

Say the engineers know how to fix the problem but it will cost an extra $500 per truck. GM sells about half a million trucks per year correct? That's $250 million a year that would come out of there pockets to ultimately fix the vibration problems. Now say the vibration only affects half a percent of trucks (2500 trucks). If they buy back each and every one of those trucks for say 50k a piece that is $125 million. Now, half of those people got the vibration fixed through wheel balancing. We are down to $62.5 million for GM to take care of the vibration vs $250 million a year for the ultimate fix. Of course GM is going to do the cheaper route and save money.

 

This is just an illustration of probably what the bean counters are doing at GM.

 

 

 

 

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[Jesse Davidson]

I was just going through an engineering book I have trying to find a formula for a vibrations problem I'm working on and found this.

 

"3.1 Introduction

 

A mechanical or structural system is said to undergo forced vibration whenever external energy is supplied to the system during vibration. External energy can be supplied through either an applied force or an imposed displacement excitation. The applied force or displacement excitation may be harmonic, nonharmonic but periodic, nonperiodic, or random in nature. The response of a system to a harmonic excitation is called harmonic response. The nonperiodic excitation may have a long or short duration. The response of a dynamic system to suddenly applied nonperiodic excitations is called transient response. In this chapter, we shall consider the dynamic response of a single-degree-of-freedom system under harmonic excitations of the form or or where is the amplitude, is the frequency, and is the phase angle of the harmonic excitation. The value of depends on the value of F(t) at and is usually taken to be zero. Under a harmonic excitation, the response of the system will also be harmonic. If the frequency of excitation coincides with the natural frequency of the system, the response will be very large. This condition, known as resonance, is to be avoided to prevent failure of the system. The vibration produced by an unbalanced rotating machine, the oscillations of a tall chimney due to vortex shedding in a steady wind, and the vertical motion of an automobile on a sinusoidal road surface are examples of harmonically excited vibration. The applications of transfer-function, Laplace transform, and frequency-function approaches in the solution of harmonically excited systems are also discussed in this chapter"

 

I plan to use this quote against them.

Edited March 2, 2016 by Jesse D

[tnchevy]

I think I have responded to either you or someone else claiming that the vibrations will cause a failure. I seriously doubt it myself, it is just an annoyance more than anything and is not acceptable IMO for a modern vehicle. I drive off road quite a bit for a living and I am always knocking off a weight or getting mud stuck in the rim which causes my work truck to usually shake like crazy on the interstate or I have dinged up the driveshaft or some other component causing it to not be "true" anymore. Drive these trucks to 150k miles with no problems due to the vibrations. Every vehicle has vibrations that are hidden before they reach the occupant through rubber body mounts or other vibration absorbing materials.

Edited March 2, 2016 by tnchevy

[Jesse Davidson]

I think I have responded to either you or someone else claiming that the vibrations will cause a failure. I seriously doubt it myself, it is just an annoyance more than anything and is not acceptable IMO for a modern vehicle. I drive off road quite a bit for a living and I am always knocking off a weight or getting mud stuck in the rim which causes my work truck to usually shake like crazy on the interstate or I have dinged up the driveshaft or some other component causing it to not be "true" anymore. Drive these trucks to 150k miles with no problems due to the vibrations.

It was me, this quote just backs me up though haha. If you choose not to believe it, thats entirely up to you. I believe that it can and will lead to more problems down the road, so this only helps my case.

[tnchevy]

I am not saying that there is 0 chance that it will be a problem, just relating my experience with years of vibrating trucks due to out of balance tires and drive line components. I do hope it helps you out with your legal pursuits though but unfortunately I doubt it will do anything to force a recall or anything for all of us that do have shaky trucks.

[Jesse Davidson]

I am not saying that there is 0 chance that it will be a problem, just relating my experience with years of vibrating trucks due to out of balance tires and drive line components. I do hope it helps you out with your legal pursuits though but unfortunately I doubt it will do anything to force a recall or anything for all of us that do have shaky trucks.

I hear ya. thats one of the reasons I post everything I find that I think may help... Anyone who wants to take the leap themselves can also use the info.

[johnrunner89]

Is this problem still present in the new Denali's with magnetic suspension? Eye on 2016 Denali but am hesitant a little.

[ekimsinnigcm]

Got the truck back today with dealer provided upgraded wheels and tires w/ a new drive shaft too. It has been there since 01/27/2016 and today is 03/02/2016. Guess what?!?! NOTHING HAS CHANGED!!! Still vibrates. I sent my final attempt repair letter 02/29/2016 so I will not be taking it back to the dealer until GM responds with where they want to make this final attempt. However, the truck is going to sit until that time because I refuse to drive it because if GM has not been able to correct the problem, how can one deem it safe to drive?

[pm26]

Is this problem still present in the new Denali's with magnetic suspension? Eye on 2016 Denali but am hesitant a little.

I would not buy one if they claimed that it floats on a cushion of air like a hovercraft.

Edited March 3, 2016 by pm26

[rpoffen]

Is this problem still present in the new Denali's with magnetic suspension? Eye on 2016 Denali but am hesitant a little.

Supposedly, yes. There are a couple posts back from someone who has a vibration on a 2016 Denali. But it is hard to says since there are likely not too many on the road yet.

[johnrunner89]

I would not buy one if they claimed that it floats on a cushion of air like a hovercraft.

Why's that?