3500 Dually - Distinct Vibration at 35-45 mph

[davereid]

2006 K3500 D/A DRW Crew Cab 12,500 miles - Vibrates at moderate speeds.

 

I first noticed a vibration during around town driving the day after I took delivery.

It was probably already there but it's only noticeable in a particular window, 35-45 mph, and coincidently, at about double that speed only it's much more rapid and less annoying at higher speed.

 

The vibration is distinct to the point that inside a cab with windows up, it produces an annoying fluttering sound at it's worst, right about 38 mph. At its' worst, the empty passenger seat next to me shakes visibly and constantly.

 

The vibration happens at that speed no matter what the circumstances are, I have tried accelerating, braking, coasting through, and coasting in nuetral, and using all gears in that range, the only common denominator is the speed, however it seems worse at the moment when I let off the pedal if I'm at that speed under throttle. It has never not vibrated at that speed. At other speeds it seems normal, after 45mph it goes away but at a little over 70 mph the ride becomes rough again up to around 80-85.

 

It's not bad at all if I'm not at those speeds, but it's bad enough every time I feel it I know there is something wrong with this truck. Both the service manager and general manager at my dealership agree.

 

Corrective actions to date:

Balance all six tires. No improvement. 1000 Miles

Balance and road force all tires, replace two. No improvement. 1500 Miles

Balance and road force all tires, replace two. No improvement. 9000 Miles

Replace with Michelin LTX, balance, roadforce, index, etc, same result, no improvement. Go back to stock tires - Wrangler AT/S from factory, balanced, indexed, same vibration remains. 10,500 Miles (never thought I'd return LTXs)

Balance front and rear driveshafts. No improvement. 10,500 Miles

 

This seems like a no brainer, if the vehicle shakes while rolling, it's tires or wheels. So far a total of 16 tires have been introduced, all balanced and indexed by the dealer. The dealer says the wheels are checked at the factory, so they must be perfect, and at this point all wheels are balanced to within acceptable tolerances. I have to say at all other speeds the ride is excellent. Has all this work on wheels and tires proved it ISN'T that or should the wheels still be measured somehow. Or does this sound like something else to you?

 

The dealer has been very cooperative in attempting to locate and repair the problem, and remains eager to solve it, but obviously we are missing something, where should they go from here?

[GM-Tech]

Subject: Suspension Vibration or Frame Beaming at 40-60 MPH (64-80 km/h) - keywords front rear shake shock spring tire #PIT3009D - (09/14/2006)

 

 

Models: 1999-2007 Chevrolet Silverado Classic

 

1999-2007 GMC Sierra Classic

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This PI is being updated to provide additional fix information and parts available. Please discard PIT3009C.

 

 

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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 at speeds between 40-50 mph (64 - 80 km/h). 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.

 

Note: Tires with excessive Radial Force Variation (RFV) or out-of-roundness can intensify the frame beaming concern. The following radial force variation numbers should be used as a guide:

 

P-Metric tires (2WD 1500)

12 lbs or less

 

P-Metric tires (all others)

24 lbs or less

 

LT-tires

30 lbs or less

 

 

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 an enhancement to the body mounts to reduce this concern on the 1500 Models. On going testing has pushed the timing of these mounts to the first half of 2007. 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.

 

 

 

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

 

 

© Copyright General Motors Corporation. All Rights Reserved.

[pm26]

Just a few other possibilities:

 

Do you have disc brakes in the back? sometimes brake rotors or drums are not properly balanced. I assume that the wheels were always balanced off the vehicle.

 

About balancing the wheels: I am not sure if it applies to this particular truck, but some vehicles have wheels that require special wheel balancer adapters because they are lug centric only, i.e. they must be mounted on the balancer the same way they are bolted on the vehicle to be properly centered. The dealer should be aware of this and should use proper balancing adapters. the word is "SHOULD". I have read of cases where Toyota 4 runner tires were not hub centric and the delaer consistently balanced the wheels wrong. Same for some Ford duallie trucks.

 

Haweka makes a set of wheel balancer adaptors that will blance non-centric wheels properly.

 

http//:www.haweka.com

 

 

The fact that there was no improvement after installing Michelim LTX tires has me somewhat suspicious that they may be balancing the wheels wrong.

 

I would try the following: Mark where the wheel weighs are on both sides of all wheels and what size. then remove them all with wheel weight pliers gently and then drive the truck. See if anything changes. If not, hammer the respective weights in the marked locations.

 

You may think that it is not possible to repeatedly balance the wheesl wrong. It is. I have seen it done repeatedly at a Dodge dealerhips. i would look for a good tire shop with a Hunter 9700 road force wheel balancer and have them check all wheels.

[GM-Tech]

Just a few other possibilities:

 

All good suggestions but this frame beaming problem is common and we deal with it all the time, so don't ignore it.

 

Try the part where it says to throw 200-500 pounds in the bed and drive it. That's a definitive test of frame beaming. If the vibration is gone, that's your "problem" and there is nothing the dealer can do to eliminate it.