Shake or Vibration Issues

[LongrangeLauber]

I think torque converter would be more related to it shuddering while driving. Well, I guess if it's out of balance it could cause vibration too

[Severado]

I think torque converter would be more related to it shuddering while driving. Well, I guess if it's out of balance it could cause vibration too

I'm sure we're referring to the same thing. Truck moves in ways it shouldn't under your behind.

[LongrangeLauber]

I'm sure we're referring to the same thing. Truck moves in ways it shouldn't under your behind.

Yeah basically, feels like it's throwing you back and forth

[Severado]

So after taking my wife's car to the shop, we find out that she has a cracked motor mount, two more are worn out, and a transmission mount is bad too. 84K on it. She has good tires, no issues with the suspension, and no alignment problems. In comparison, the rough ride, shudder, vibration, etc.. is mighty similar to these new trucks. Maybe they need to start replacing mounts. If this was covered somewhere in this thread please correct me. Any thoughts?

[C6Bill]

Lots of talk about the newly designed cab and or motor mounts early on. I don't remember it leading anywhere. I think some noticed improvements by backing off the bolts that hold the cab to the frame then torquing them again.

[Severado]

Lots of talk about the newly designed cab and or motor mounts early on. I don't remember it leading anywhere. I think some noticed improvements by backing off the bolts that hold the cab to the frame then torquing them again.

I remember the body mount talk. I remember the motor mount shim TSB. They performed that "fix" on my truck.

 

Friend of mine said my truck rides smooth. I must be sitting in the wrong seat if that's the case. Maybe my expectations are not set low enough .......

[mgoodling44]

Agreed sounds like like there's too much backlash. The carrier bearing preload may have been to loose letting the backlash open up when the load is removed.

Interesting. I was leaning towards hitting the torque converter up next. I have to take the truck into the dealer to have the hitch replaced (recall), and I think I'm going to ask them to validate a few things while I'm in there.

- Drive shaft balance

- Pinion angle check

- Rear shocks set up (there's a 'knock' in the rear when hitting bumps in the road).

 

Is there a way to test / diagnose the carrier bearing? Anything else that I can have them validate while it's at the dealership?

[Severado]

So I've been trying to correlate the collective symptoms reported in this forum by possible failing parts that cause it. I'm not a mechanic, just a guy with a truck thinking out loud through my keyboard.

 

1. Out of balance tires seems to be the favorite fall back of the service department. Masks the problem when you can get 4 good ones. But causes more of a hard wobble than a shake or shudder.

2. Motor vibrations amplified by the stiff frame. Mostly felt through the steering wheel when moving and when idling in gear. Feels like a misfire, definite vibration not a shudder/shake. Shims band-aid the vibe for a while but this is not a fix.

3. Sub-par shocks and struts don't buffer normal road vibrations and get amplified. I have to separate this into it's own bullet point. Replacing them with known better parts is noticeable right away. I've read or watched how a new set will do wonders. Drive-ability was improved.

 

That leaves us with parts that require more diagnosis from service centers.

 

4. Torque converter. The main symptoms of a bad torque converter is shuddering, slipping(gears), and poor gear engagement. How many of you experience shuddering/shaking between 30 - 45 MPH? I know I do. They'll try to update\reset or it will actually force them to look at the rest of your transmission before replacing the torque converter. I'm sure the warranty covers this, but they don't want to pay the dealers for the hours it takes.

5. Driveshaft. This has been explained to death and you can find video. Shaky driveshaft, shaky truck.

6 Axle problems. This doesn't apply to every configuration. I've seen the posts about some being bent. And others where the ring and pinion are damaged.

 

Living with the "shake" forces me to ramble about it. If they say anything else about out of balance tire(s), I'm going to get GM involved in getting another brand. I have the Continental LX20, which is best suited for SUVs (Tahoe) with air ride or magnetic ride control. Maybe I may have to buy my own tires to get something better. But not until they check out my torque converter and drive shaft.

[mgoodling44]

So I've been trying to correlate the collective symptoms reported in this forum by possible failing parts that cause it. I'm not a mechanic, just a guy with a truck thinking out loud through my keyboard.

 

1. Out of balance tires seems to be the favorite fall back of the service department. Masks the problem when you can get 4 good ones. But causes more of a hard wobble than a shake or shudder.

2. Motor vibrations amplified by the stiff frame. Mostly felt through the steering wheel when moving and when idling in gear. Feels like a misfire, definite vibration not a shudder/shake. Shims band-aid the vibe for a while but this is not a fix.

3. Sub-par shocks and struts don't buffer normal road vibrations and get amplified. I have to separate this into it's own bullet point. Replacing them with known better parts is noticeable right away. I've read or watched how a new set will do wonders. Drive-ability was improved.

 

That leaves us with parts that require more diagnosis from service centers.

 

4. Torque converter. The main symptoms of a bad torque converter is shuddering, slipping(gears), and poor gear engagement. How many of you experience shuddering/shaking between 30 - 45 MPH? I know I do. They'll try to update\reset or it will actually force them to look at the rest of your transmission before replacing the torque converter. I'm sure the warranty covers this, but they don't want to pay the dealers for the hours it takes.

5. Driveshaft. This has been explained to death and you can find video. Shaky driveshaft, shaky truck.

6 Axle problems. This doesn't apply to every configuration. I've seen the posts about some being bent. And others where the ring and pinion are damaged.

 

Living with the "shake" forces me to ramble about it. If they say anything else about out of balance tire(s), I'm going to get GM involved in getting another brand. I have the Continental LX20, which is best suited for SUVs (Tahoe) with air ride or magnetic ride control. Maybe I may have to buy my own tires to get something better. But not until they check out my torque converter and drive shaft.

Well said. And I agree with everything that you've said. I, too, and not a mechanic, but fairly mechanically inclined. However, after reading the feedback from the post, and documenting all my issues in a log (trans temp, outside temp, vibration speeds, etc), my approach is simply this. GM/Dealerships will have a protocol to follow in diagnosis. We have to accept that. I get it. We have to be diligent, and demand with the dealership that the issues are not resolved, and document concerns on the service records. Enact Lemon Law when eligible, if desired. Or continue to self diagnose and try to find a fix for this. I'm leaning towards the latter. As baffling as it is, it is a challenge.

 

Here is where I'm at in the game:

Dealership said it was 100% tire related. I bought new LTX AT/2's. Still have vibration.

Going back into the dealership tomorrow.

Requesting to have drive shaft validated (balanced)

Requesting to have pinion angle validated

Requesting to have shocks inspected and tested.

 

Here's what I think (logically), at least for my particular truck.

* The ring and pinion are a very sensitive set up. My symptoms are leaning that way (more of a vibration with decelerating/coasting, 45-55 mph.) Could be the carrier bearing (thanks to the forum for the education). Upon deeper investigation, this appears to be the obvious target.

 

The question is how do I get the dealership onboard?

 

Torque converter would be my next option (this is what I originally thought it was). Now I'm leaning towards the ring/pinion/carrier bearing.

[abominable z71]

Interesting. I was leaning towards hitting the torque converter up next. I have to take the truck into the dealer to have the hitch replaced (recall), and I think I'm going to ask them to validate a few things while I'm in there.

- Drive shaft balance

- Pinion angle check

- Rear shocks set up (there's a 'knock' in the rear when hitting bumps in the road).

 

Is there a way to test / diagnose the carrier bearing? Anything else that I can have them validate while it's at the dealership?

The only way to check it is to open up the rear end and check the backlash. GM has a procedure that walks the technician through the process and tells them exactly what tools to use. IMHO this is work better suited for a shop that specializes in rear end work, they do it all day everyday and setup a R&P in their sleep. The dealership not so much. Unfortunately warranty only covers the dealership to perform it. in my experience when they do find rear end issues it's a bout 50/50 between swapping gears and installing a complete rear end and also 50/50 it fixing the issue. Some say new rear end...problem solved others say better but not gone. Good Luck

[abominable z71]

So I've been trying to correlate the collective symptoms reported in this forum by possible failing parts that cause it. I'm not a mechanic, just a guy with a truck thinking out loud through my keyboard.

 

1. Out of balance tires seems to be the favorite fall back of the service department. Masks the problem when you can get 4 good ones. But causes more of a hard wobble than a shake or shudder.

2. Motor vibrations amplified by the stiff frame. Mostly felt through the steering wheel when moving and when idling in gear. Feels like a misfire, definite vibration not a shudder/shake. Shims band-aid the vibe for a while but this is not a fix.

3. Sub-par shocks and struts don't buffer normal road vibrations and get amplified. I have to separate this into it's own bullet point. Replacing them with known better parts is noticeable right away. I've read or watched how a new set will do wonders. Drive-ability was improved.

 

That leaves us with parts that require more diagnosis from service centers.

 

4. Torque converter. The main symptoms of a bad torque converter is shuddering, slipping(gears), and poor gear engagement. How many of you experience shuddering/shaking between 30 - 45 MPH? I know I do. They'll try to update\reset or it will actually force them to look at the rest of your transmission before replacing the torque converter. I'm sure the warranty covers this, but they don't want to pay the dealers for the hours it takes.

5. Driveshaft. This has been explained to death and you can find video. Shaky driveshaft, shaky truck.

6 Axle problems. This doesn't apply to every configuration. I've seen the posts about some being bent. And others where the ring and pinion are damaged.

 

Living with the "shake" forces me to ramble about it. If they say anything else about out of balance tire(s), I'm going to get GM involved in getting another brand. I have the Continental LX20, which is best suited for SUVs (Tahoe) with air ride or magnetic ride control. Maybe I may have to buy my own tires to get something better. But not until they check out my torque converter and drive shaft.

Every model year that comes out new people come here with the same problem and GM still hasn't come up with a fix. As far as trying to figure out what part is contributing to the vibe, if the dealership puts the truck on the PICO scope you need to get a copy of the results. Different components will have different frequencies at whatever speed you feel the vibration. The 70+ vibration is typically T3 vibration on the scope. This is not a tire balance issue. A tire balance issue would be a T1 meaning that their is an unbalanced mass in the tire and wheel assembly that causes a one "disturbance" per rotation. A T3 vibration is where things get tricky. This is a third order vibration meaning that for every rotation of the tire there is 3 disturbances. This kind of problem cannot be a mass imbalance and they assume the issue is out of round tires or force variation in the sidewalls or a combination. This is where the road force comes into play. It measures the variation in the stiffness of the sidewalls of the tire. These are the road force numbers that people talk about. So when they say 25 lbs what they mean is that stiffness of the sidewall varies by 25 lbs as the tire rotates, this variation is felt as a vibration. So they force match the tire to the wheel, they basically rotate the tire on the rim to try and minimize the variation, if they can get the numbers low enough they then balance the tire and this what the Road Force Balance is. It is 2 separate unrelated processes that get rolled into 1. Many people myself included have noticed the vibration is better or gone for a while but comes back. After it comes back they check the force variation again and it's different. Too many variables to account for, Tire pressure, temperature, tire break in, etc. the spring rate of rubber is constantly changing with these variables. The kicker is that this happens with every tire on every truck but only some have the vibration issues. many have swapped tires from trucks that do not vibrate and still have the vibration so whats the issue. 1 of 2 things. Either the vibration source is not the tires, possible, The hubs, rotors, axles all turn at the same speed as the tire. Or there is a resonance issue meaning that the vibrations from the tires are always there on every truck but only make their way into the cab on some trucks. This can be as simple as the body mounts which to my knowledge no one has tried replacing on a vibrator to date. This is what I would really like to see. Take the body mounts off of a truck that does not vibrate and install on a truck that does. Or it can be as complex as the metallurgy of the frame itself is just the right ratio of stiffness to mass that its natural frequency matches a third order tire vibration at 72 mph and shakes. Either way it has proven itself to be unfixable for almost all trucks that experience the 70-80 MPH vibration.

 

Motor mounts, torque converters and so on. Try the truck at the same speed in different gears. 72 mph in 4th 5th and 6th gear if the vibration frequency is unchanged these are not your source if they were the vibration you feel you should feel significantly different because their rotational speed will be different. Example for a truck with 3.42 rear end and factory 275 55 20 tires at 72 mph the tire rotates at 759 rpm or 12.65 Hz. A first order tire vibration would be 12.65 Hz second order would be 25.3 Hz and third would be 37.95 Hz. At this speed in 6th gear the engine and torque converter is 1731 rpm or 28.85 Hz. 5th gear would be 36.85 Hz and 4th gear would be 49.81 Hz. If the vibration source was the motor or torque converter the vibration you feel should match those frequencies.

 

Drive shaft: This is directly proportional to tire frequency by whatever rear end the truck has. 3.42 rear end would have a frequency of 3.42 times the tire. Same example as above, tire at 72 mph rotates at 12.65 Hz so the drive shaft rotates at 43.26 Hz. A drive shaft vibration due to out of balance would vibrate at 43.26 Hz at 72 mph. Bad pinion angle is a little different because the drive shaft is speeding up and slowing down as it rotates. Typically pinion angle causes a second order drive line vibration or a vibration of 86.2 Hz at 72 mph. These frequencies are speed related and would be lower at slower driving speeds I'm just using 72 mph for examples.

 

The rear end. Vibrations from the rear end have been linked to the vibration in the 45-55 mph range and typically show as a 1st order tire vibration. This requires them to check the pitch line runout which is the backlash variation from tooth to tooth. It could also be excessive backlash between the coast side of the ring gear teeth and pinion gear which is why you feel it when you let off of the gas.

 

The fact is GM knows there is an issue with this platform because there is a TSB addressing these issues with a bunch of band aids to try and fix it. But no definitive fix and often they'll go through the whole thing accomplish nothing other than having your truck in their service department for months usually you get your truck back in worse condition, meaning you hear many stories about scratches, dings and dents that were not there when you took it in, you made one or 2 truck payments on a vehicle you didn't drive for that time that has acquired an additional 500 miles or more, you're now in the same vibrating POS and all GM has to say is "operating within spec". Then begins the BBB or lemon law procedure, more attempted repairs, arbitration, shitty offers from GM like 1 months payment for a truck you haven't been able to drive for 3 or a few grand in trade assist but even the dealership doesn't want to give you decent value on your vibrating POS, then after many months and lost $$$ hopefully some sort of solution. Good looking trucks though, LOL.

[BIGDOGx]

Lots of talk about the newly designed cab and or motor mounts early on. I don't remember it leading anywhere. I think some noticed improvements by backing off the bolts that hold the cab to the frame then torquing them again.

 

A tech at my dealer a few months ago stated those motor mounts are the true reason for the odd tunes that these trucks come loaded with. He says that gm was having issues with the mounts basically snapping off the frame, and is the true reason for the detuned feeling in our engines and horrible shift patterns. Whether that has any truth to it i don't know but it sounds plausible imo.

[Harmholland]

the deal is they take mine and give me a new 2017. whether I keep it or not is another story, not sure what Ill do at the moment, I'm terrified to have the vibration come back, and I already know that it is very very slight on the 2017 denali's I tested. im trying to get them to put better tires on before I accept.. If its gone I'll consider keeping it, if its still there I'm going straight to Ford or Toyota... I think

So in 2017 we still shaking? Has GM fired all engineers.

[14silverado4.3]

I will just leave this here.

 

My buddy and I went on a trip in his 2016 Silverado. I felt the same seat vibrations and the shaky center console. Boy she is really wobbly today was the comment from him.

 

My buddy is service manager for Chevrolet who has done everything he can do for my truck.

 

He can't or won't even acknowledge that there is a fix or that any of this is normal. It is like totally not phased by the problem.

[Jesse Davidson]

So in 2017 we still shaking? Has GM fired all engineers.

That is correct 2017's have the same vibration, even the Denali's that I test drove. they were no where near as bad, but it was sill there.