3 new lemons in a row ( vibrations)

[Silverado Steve]

Yeah, i think i would look elsewhere if i were you OP...you gave it your all. Maybe GM will refuse to sell you a truck because they keep losing money with all these buybacks with you...lol

[Spurshot]

Is this a 1500 problem in the extreme sense? The 2500 seems to be less problematic. I had 104k on the Sierra with zero shaking/vibration issues. I beat that thing senseless at times too. Seems that most of the big issues surround the 1500 platform. Maybe underdesigned?

 

 

They have to put good tires on a 2500.

[Silver16]

They have to put good tires on a 2500.

 

So tires are the issue? That is an easy fix for GM. Wonder what thier thinking or not.

[Spurshot]

So tires are the issue? That is an easy fix for GM. Wonder what thier thinking or not.

 

Tires are one of the most frequent issues, from what I've read. Some guys go thru more than one set of factory fleet tires before they get good ones. I found I never liked the 1500 fleet tires in the 2 1500's I've owned, and just gave them away and went right to LR E tires for my off-roading. I never had an issue with my 1999 1/2 2500 OEM tires. They were LR E. I think some tires are just not going to maintain their roundness and balance.

[O_J_Simpson]

Sure sounds like you keep repeating the same purchase but expect different results...

[KARNUT]

My wife's 11 Genesis had three sets of tires before road noise and vibrations quit. The first two sets where rotated every 3700 miles with oil changes. Usually at 10K miles it would start with noise then vibrations would set in and get worse with each mile. The last set have gone 50K miles no problems. The first set wore out quick, the second set discount tire warranty and gave me 4 tires for the price of two. It's the wife's car and she didn't mind the noise and used mostly in town, I would have traded it.

[abominable z71]

It's clear you have a technical background and you identified the vibe frequency. You undoubtedly know 40 htz is too high for tires at the speeds you mentioned. I'd suspect the driveshaft going through a natural frequency resonance.

While 40 hz is too high for a first order tire vibration at about 12-13 HZ at freeway speeds, it is right on the money for a third order tire vibration at about 75 MPH. Generally 2nd, 3rd and higher order harmonics are ignored because the amplitude diminishes, unfortunately if you have designed a truck with a natural frequency around 40 hz you have the perfect recipe for resonance and that's the underlying issue with this platform. Unfortunately there are a lot of other items with the same frequency as the tires that can be the source as well. (hubs, rotors front drive shafts, rear axle shafts, ring gear and so on) First order vibrations are usually mass imbalances and easy to correct, harmonics are another story altogether and why after 4 years this problem still persists on this platform. A redesign of the body mounts to prevent the transmission of the vibrations from the chassis to the cab would be the easy fix but I'm sure the numbers have been run and GM has deemed this to expensive to pursue, Their stance is likely "so we loose a few customers, oh well"

[Spurshot]

While 40 hz is too high for a first order tire vibration at about 12-13 HZ at freeway speeds, it is right on the money for a third order tire vibration at about 75 MPH. Generally 2nd, 3rd and higher order harmonics are ignored because the amplitude diminishes, unfortunately if you have designed a truck with a natural frequency around 40 hz you have the perfect recipe for resonance and that's the underlying issue with this platform. Unfortunately there are a lot of other items with the same frequency as the tires that can be the source as well. (hubs, rotors front drive shafts, rear axle shafts, ring gear and so on) First order vibrations are usually mass imbalances and easy to correct, harmonics are another story altogether and why after 4 years this problem still persists on this platform. A redesign of the body mounts to prevent the transmission of the vibrations from the chassis to the cab would be the easy fix but I'm sure the numbers have been run and GM has deemed this to expensive to pursue, Their stance is likely "so we loose a few customers, oh well"

 

I haven't experienced the vibe in a K2, so I don't have an inclination that the frame natural frequency is an issue. But if it is an issue, a simple large change in the frame natural frequency by adding mass might be confirm it as a problem.

[SierraRover]

The comments in this thread make sense. I am NOT an engineer, but have read enough on this problem to think the basic vibration can come from tires, driveshaft, etc. Then the frame of the truck resonates, vibrating at 38-40 Herz, which is probably a harmonic of the basic source vibration. So balancing or even replacing tires is sometimes successful in solving or mitigating the overall truck vibration. And some GM trucks don't have a noticeable problem at all.

 

My truck -- a short wheelbase, regular cab Sierra 1500 -- probably has may have less potential for vibration than a long bed -- because there is less frame length to flex, a shorter drive shaft, etc. But it still vibrates. I can live with it around town. This is terrible truck to take on a highway trip, however.

 

The amplitude goes up the faster I go, but the rate of vibration (the frequency) stays the same. Sometimes it rises and falls in amplitude, creating almost a buffeting effect, perhaps indicating two sources or a source plus a harmonic of another source are reaching the frame at the same time.

 

Here is a video of what it looks like at 68 mph: https://youtu.be/lYtORlwqddw

[SouthernSilveradoGuy85]

The comments in this thread make sense. I am NOT an engineer, but have read enough on this problem to think the basic vibration can come from tires, driveshaft, etc. And then the frame of the truck resonates to that frequency or at one of the harmonics (e.g., double or triple the frequency). So balancing or even replacing tires is sometimes successful in solving or mitigating the truck vibrations. And some GM trucks don't have the problem at all.

 

My truck -- a short wheelbase, regular cab Sierra 1500 -- probably has less potential for vibration than a long bed -- because there is less frame length to flex, a shorter drive shaft, etc. But it still vibrates. I can live with it around town. This is terrible truck to take on a highway trip, however. (I really like this 2014 GMC in almost every other way).

 

My vibration starts around 30 or 35 mph and continues up from there. It is really bad over 65. It may have multiple causes -- sometimes it rises and falls, creating almost a buffeting effect, perhaps indicating two sources or a source plus a harmonic of another source are reaching the frame at the same time.

 

A short wheel base truck may vibrate less from the frame or components themselves. But, from my understanding being a shorter frame and all the truck tends to feel the bumps more than a longer frame truck. Think of it as seeing that a long wheelbase truck can flex more and easier than a short wheelbase. So your vibrations could be more of just the truck feeling the bumps more. Same as a small tire sidewall will make you feel the bumps more because the sidewall flexes less than a tire with a lot of sidewall. I could be wrong, just what I'm thinking. I've never had a reg cab short bed, but going off what others on this forum has said. At least it's how I remember what I've read.

[SierraRover]

It's true that the regular cab/short bed is a bumpy ride!

[SouthernSilveradoGuy85]

I'm starting to think that maybe it has something to do with the driveline. Maybe the mounting plates on the rear axle for the leaf springs on the rear axle are in the wrong place which is putting the driveshaft u-joints of each end at different angles. The angle from the transfer case or transmission should mirror the angle of the axle to cancel out the vibrating of each end.

[SierraRover]

The shaking cup video is at:

[kthomas72]

It is most definitely not the tires. My factory driveshaft was not straight, out of round and unbalanced and there was no way to fix it so i had a reputable shop build me a new one.

 

Also look at the rear axles, mine were out of round at the flange and the studs.

 

Also look at front axles ( if 4x4 ) as for mine again were not straight from the factory.

 

Multiple sets of wheels and tires with no fix, still vibrates and grinds like it has 200k + miles on it.

 

(2015 Crew 6.5 Bed 4x4)

[SierraRover]

I fixed my vibration problem in my 2014 GMC Sierra. I traded it in on a new vehicle -- not a GM -- on 20 Aug 17.