honing/vibration at 60mph+

[hoorders]

My truck has developed a honing noise/vibration that you can feel on the floor board while at highway speeds......60mph+.

 

Seems to be worse if I don't accelerate and just maintain speed....almost just backing off the throttle a touch at speed. If I get on the throttle it seems to go away some. I checked the wheel bearings and they seem fine.I also grabbed hold of the front drive shaft to check the u-joints and I think they are ok as well. I did notice a couple of things when checking the front drive shaft. One, is I can't spin the drive shaft by hand....feels like its engaged......I don't know if this is normal and if maybe the vibration is the front axel engaged. Secondly I noticed there is some play up and down and side to side on the front out put shaft of the transfer case. I can wiggle the back of the front drive shaft enough to make some noise.....is there supposed to be play there?

 

I was going to test drive the truck with no front drive shaft in it....will I will damage anything if I test drive my truck with no front drive shaft??

 

I've got the auto trac system.

 

Sorry to be rather long winded.......just wnated to try and explain what is going on.

 

Thanks......

[ChevyTech007]

I hate to say it but it sounds like a frame beaming concern. I have been round and round with one. We actually had to call a GM engineer in to help. He advised that nothing could be done to fix it. Below is a bulletin to describe the condition.

 

 

Subject: Suspension Vibration or Frame Beaming at 40-60 MPH - keywords chuggle rear shake shock spring TCC tire #PIT3009C - (06/28/2006)

 

 

 

Models: 1999-2007 Chevrolet Silverado Classic

 

1999-2007 GMC Sierra Classic

 

 

 

 

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This PI is being updated to add 2007 model and to advise that no more FPR are needed. Please discard PIT3009B.

 

 

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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

 

Condition/Concern:

Beam shake vibration is usually felt in the seat and occurring between 40-50 mph. Hertz readings using an EVA tool are normally between 8-24 Hz. This condition is most common on extended cab and crew cab models but has also been noted in other models.

 

Recommendation/Instructions:

The severity of beam shake may vary from vehicle to vehicle. To determine if the concern is beam shake, please perform the following:

 

Test drive vehicle to confirm the condition. A beam shake condition will usually respond to concrete type pavements more than asphalt, so the vehicle should be driven over both surfaces if possible.

Place 200-500 pounds in the pickup bed between the closed tailgate and the wheel wells. A beaming condition should dissipate.

If the concern is determined to be beam shake, this is a characteristic of the vehicle and currently no repair attempts should be made. With your help in the use of the Field Product Reporting process GM Engineering is currently developing a enhancement to the body mounts to reduce this concern on the 1500 Models and should be available shortly. There will be no enhancement made to the 2500 and 3500 models. At this point no more Field Product Reports are needed and Thanks for your help.

 

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

[hoorders]

I hate to say it but it sounds like a frame beaming concern. I have been round and round with one. We actually had to call a GM engineer in to help. He advised that nothing could be done to fix it. Below is a bulletin to describe the condition.

 

 

Subject: Suspension Vibration or Frame Beaming at 40-60 MPH - keywords chuggle rear shake shock spring TCC tire #PIT3009C - (06/28/2006)

 

 

 

Models: 1999-2007 Chevrolet Silverado Classic 

 

1999-2007 GMC Sierra Classic 

 

 

 

 

--------------------------------------------------------------------------------

 

This PI is being updated to add 2007 model and to advise that no more FPR are needed. Please discard PIT3009B.

 

 

--------------------------------------------------------------------------------

 

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

 

Condition/Concern:

Beam shake vibration is usually felt in the seat and occurring between 40-50 mph. Hertz readings using an EVA tool are normally between 8-24 Hz. This condition is most common on extended cab and crew cab models but has also been noted in other models.

 

Recommendation/Instructions:

The severity of beam shake may vary from vehicle to vehicle. To determine if the concern is beam shake, please perform the following:

 

Test drive vehicle to confirm the condition. A beam shake condition will usually respond to concrete type pavements more than asphalt, so the vehicle should be driven over both surfaces if possible.

Place 200-500 pounds in the pickup bed between the closed tailgate and the wheel wells. A beaming condition should dissipate.

If the concern is determined to be beam shake, this is a characteristic of the vehicle and currently no repair attempts should be made. With your help in the use of the Field Product Reporting process GM Engineering is currently developing a enhancement to the body mounts to reduce this concern on the 1500 Models and should be available shortly. There will be no enhancement made to the 2500 and 3500 models. At this point no more Field Product Reports are needed and Thanks for your help.

 

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

<{POST_SNAPBACK}>

 

 

 

Im not so sure its beam shake.

 

I just pulled the front drive shaft out and went for a little stroll down the road. Its much better. While I was under the truck I was trying to figure out why I could not spin the drive shaft by hand. I dropped the front of the drive shaft off the front diff and I could spin the shaft no problem while it was still on the transfer case.....which means the transfer case end is spinning freely. I grabbed hold of the front diff (where the drive shaft bolts on to) and I could not turn it......so my front diff is engaged which leads me to beleive the vibration i was getting is because my front axel is engaged and with my drive shaft in, its spinning not only the front axel but also the transfer case.

 

So I just need to figure out why my front diff is engaged.

[Raymond S.]

ChevyTech007,

What do you do if it is determined to be beam shake? My dealer is telling me it the body mount where the step bar is located on the Left front of the cab mount. Is there anything that can be done or are we stuck w/ what we got?