2007 Nbs Highway Vibration

[kstell]

Add me to the 70 MPH highway speed vibration, shudder, shake or whatever you call it...

 

Specifics:

 

New to me - owned over 1 month

07 NBS Silverado Ext cab SB 4x4. 28K miles, with 20K on aftermarket rims and tires. No mods except soft tonneau cover Rims are 20" BOSS 315 and tires are Yokohama AVID SUV.

 

I rarely run the truck on the highway, but his past weekend I took a 600 mile trip. At speeds up to 60-62 MPH, the truck runs fairly smooth. As I approach 70, I notice a shudder in the steering wheel and I can also feel it in my seat. If there was milk in my water bottle that was in the console, it would turn to butter.

 

Varying Degrees:

 

Now , the funny thing is it isn't consistent. Sometimes it isn't there and sometimes it gets so bad, that my wife has a big smile on her face. Also, road conditions play a small part, but it doesn't matter if it's concrete or asphalt. A new stretch of asphalt road lessened it and having a light load (<100 lbs) also seemed to help. I also notice that long sweeping turns

help initiate the shudder and once straightened out, it's as if the shudder has to play itself out... Like a frequency decay. Increasing speed to over 75 MPH, only increases the shudder freq and thus it feels like it runs smoother. Anything under 65, and it is almost smooth as glass.

 

I have tried running with the soft tonneau cover rolled up and closed. No change or affect.

There is no shudder when braking and the engine runs smooth. I have AFM and I saw no affect in V4 or V8 modes other than being able to feel the shift between modes which is almost imperceptible.

 

I just got back after having them road forced balanced. The balance was off only very slightly. There were no obvious tire run outs, bulges or egg shape. I haven't had a chance to highway check it out, since the highways around here are all under construction and going 25 MPH is enough of a challenge, let alone 70.

 

In essence, I want to eliminate the wheel/tire combo from the equation.

 

I have not taken it in the dealer yet, as I want to document more data. I see from other posts, that this is not an isolated condition. Some have blamed driveshafts, some frame harmonics and some the rotation of the earth. I want to set up an appointment with the dealer to document my case, before the warranty runs out.

 

Does anyone have any further data on this that I can bring to the service adviser's attention or any hints, tricks or areas to look at?

 

Thanks in advance...

[stadt11]

My sister had a similar problem on her car. I found that it would not shake/shutter until 70+. I found out the rotors were warped. I also had to replace the pads because they were also wearing unevenly.

 

Another thought, if you put the original wheels/tires back on (if you still have them, or can borrow some), you could eliminate your aftermarket wheels/tires.

[asilverblazer]

Bent wheel?

[HawkeyeOC]

This was a major problem on previous GMT-800 trucks. NBS 900 trucks are completely different though. Frame and front suspension are all new. Harmonics shouldn't be a problem.

Switching out the tire/wheel combo would be a likely place to start to eliminate that possibility. Hopefully it wasn't in an accident

[2000DV4.8]

Probably isn't your problem, but just for the hell of it, did you take the clips off of the rear drums? They interfere with some aftermarket wheels and don't let them seat properly, leading to vibrations.

 

They are just there to help hold the drum on during assembly, and isn't needed anymore.

[Silverado4x4]

Could be the driveshaft slung a weight off making it unbalanced have them check it. Warped rotors will only shake under braking.

[kstell]

Yes, the clips were removed as I checked when they had the wheels off.

I thought it felt like a loose belt in a tire that managed to slip back into place. I though this would explain the inconsistency of the shaking. I had them rotate the tires and I will report back after I can get it up to speed. The next step is to re-install the OEM wheels/tires.

 

I have heard reports of bad wheel hub assembles on the 900's from other forums. but I digress. The interior is so damn quite (I have the LTZ) it hard to pick up sounds outside..

 

 

Probably isn't your problem, but just for the hell of it, did you take the clips off of the rear drums? They interfere with some aftermarket wheels and don't let them seat properly, leading to vibrations.

 

They are just there to help hold the drum on during assembly, and isn't needed anymore.

[gvbhunt]

Not that it is really that easy to do but maybe a bent axle? Have someone drive next to/behind you and see if they can notice any wheel "wobble" or if they can see a tire start to bounce when you notice it in the cab.

 

Possibly a failing end link on the steering? They would be greasy on the outside if they were starting to leak.

 

I would have to say probably not brakes as if it was it would be amplified 10x when you were braking.

 

Dumb question but you do not have it in Auto 4x4 do you?

[pm26]

Were the rear drum balancing weight ground off or removed by any chance to acomodate the aftermarket wheels?

 

 

I would first suspect a loose belt in one of the tires. Find a place that has a Hunter 9700 model wheel balancer/road force machine and have all four tires checked for road force variations. They will be able to tell if there is a problem with the tires. The machine simulates on-road tire condition by pressing a pneumatic roller with something like 1,000 lbs of force against a rotating wheel mounted on the machine.

[zxcv]

Probably isn't your problem, but just for the hell of it, did you take the clips off of the rear drums? They interfere with some aftermarket wheels and don't let them seat properly, leading to vibrations.

 

They are just there to help hold the drum on during assembly, and isn't needed anymore.

 

 

+1 This has been the solution to a ton of similar problems, and hopefully it works!