issue Vibration in Floorboard, Not Speed/Tire Related

[VMaxtastic]

I get a pretty good vibrating under harder acceleration. it seems to travel through the floorboard from the front to the back. I am going to wait a while to take in to dealer so they can try and iron the others first. maybe come up with a proper fix.

I get the exact same vibration under heavy acceleration.

[rjhdakota]

Just wanted to post an update. Took it to the dealer today to get the exhaust/heat recall done, took them 2.5 hours to do this, said they had laptop problems. They took it for a drive and said it was normal. I was out of time to go out with them so I did not pursue further. I only have 800 miles on it, so I will wait until I have 2-3K miles on it and see if it goes away. I think its the exhaust mounting as you can hear the exhaust change tone when it happens so its resonating. A shame though as its so smooth at 50 and 70mph, buzzy at 60-65. Fix for now is to move my foot as far to the left as I can!

 

-Rich

[brendon444]

I get the exact same vibration under heavy acceleration.

Got the same viberation in my denali at full throttle say when passing. And to top it off my screen just quit on intellink like someone else mentioned in this thread! Bought a new truck to be reliable.

[VMaxtastic]

Got the same viberation in my denali at full throttle say when passing. And to top it off my screen just quit on intellink like someone else mentioned in this thread! Bought a new truck to be reliable.

How many miles does yours have? So far my screen still works. It has 1500 miles.

[bigsapper]

There is a PI out that addresses vibrations in the 30-35 mph range that is related to the driveshaft. Generally when we see a u-joint or driveshaft issue you will feel it in the floor and it can be more or less noticeable with a load on the drive train. Could be what is causing the issue for you.

 

Craig

 

What is a "PI"?

 

[1kwik72]

What is a "PI"?

Preliminary Information bulletin. Basically the first round of Technical Service Bulletins

[kazaman]

Preliminary Information bulletin. Basically the first round of Technical Service Bulletins

I also have the same vibration under full throttle and slightly at idle. If I accelerate hard from a stop feels like the gears have marbles in it. Original dealer tells me vibration is normal. Spoke to GM and they advised to visit another dealer. Traded a 99 Z-71 which was smooth as glass. Hoping GM comes with a TSB soon, as this is annoying.

[Aaron1085]

I've had similar issues. I thought it was perhaps snow in the wheels and it being cold / icy....then I thought maybe an odd balanced tire. But it persists ever so slightly at medium speed.

 

Sent from my DROID RAZR HD

 

 

[TxTruckMan]

I've been monitoring my problem for a couple of weeks now in preparation for bringing it to the dealership. My problem is the worst at 1750 rpm with a slight load on the throttle. I did a 700 mile trip this weekens and my left foot was tingling the whole time. At highway speeds (75-85) I'm right around that rpm. My problem also feels worse around the dead pedal. If I keep my foot off of it it helped.

[14SLTZ71]

I've been monitoring my problem for a couple of weeks now in preparation for bringing it to the dealership. My problem is the worst at 1750 rpm with a slight load on the throttle. I did a 700 mile trip this weekens and my left foot was tingling the whole time. At highway speeds (75-85) I'm right around that rpm. My problem also feels worse around the dead pedal. If I keep my foot off of it it helped.

Any updates? I have the same problem. Pretty sure it is resonance from the exhaust. Probably because there is a cat directly under the gas pedal.

I installed Dynamat Xtreme and Dynapad in the driver's floorboard, it didn't help, just a waste of time and money.

The adjustable pedal doesn't help either because the accelerator pedal sits loose in the mount and it makes the pedal vibrate/resonate worse.

They also ran the shift cable thru the floor under the drivers floorboard carpet but I'm not sure if this contributes to the problem?

Edited March 16, 2014 by 14LTZZ71

[rjhdakota]

Has.any one checked the exhaust mounts under the floorboard? I will check as soon as it warms up here! If there is a mount close by, a good test would be to remove it, or loosen it, and see if makes any difference. That would rule out the exhaust. But I agree, I bet its the exhaust.

[14SLTZ71]

I think the exhaust causes the floorboard to resonate because they are making the floorboards with thinner and cheaper materials to save money. If you get underneath and tap on the floorboard you will see what I mean.

Edited April 3, 2014 by 14LTZZ71

[Bobtorious]

Hi guys,

 

I was having the exact same problem with my Denali. I took it to the dealer explaining it felt like a very, very bad imbalance in the rear wheels and told them to keep it until they figured it out. It took them a few days, and I just got the truck back today. The rears had gone out of balance and they couldn't get them to balance. They replaced them and the vibrations got better, but they are still there. Although, I know you mentioned it didn't feel like a balance issue, I wanted to chime in.

Edited April 11, 2014 by Furynation

[2doorpost]

At 1K miles....Getting a really slight drone/vibration at 40 mph at certain pedel pressure- let off and it goes away. Not a huge problem but with the truck being so quiet otherwise, I notice it.

 

Made an appointment for next week for the dealership to check it out and well see what happens.

[14SLTZ71]

I have managed to get rid of about 90% of the exhaust resonance vibration in the floorboard and accelerator pedal.

This is what I have done so far;

Installed the Range V8 which helped some by keeping the engine out of V4 mode.

I Clamped weights to the pipe after the muffler but before the resonator which made a big difference (see pics below). This was done mainly to determine which area of the exhaust was generating the resonance.

I think the bent portion of the pipe going over the rear axle in the spare tire area is causing most of the resonance. The resonator right before the exhaust outlet may have something to do with it as well, but it's definitely being generated after the muffler.

 

Next step will be to install a helmholtz resonator like the one in the pic below. I will make it adjustable until I determine the correct length needed to cancel out the resonance, then it will become permanent.

 

I DID NOT WEIGH the WEIGHTS before mounting.

Edited April 12, 2014 by 14LTZZ71