BEAM SHAKE???

[Nitro276]

I purchased an'06 GMC Sierra K2500HD SLE2 Crew Cab with the Duramax in it on 6/19/06. I have approximately 1,800 miles on it now. Somewhere after 1,000 miles, the truck started riding incredibly rough, like an 80,000 lb GVW unloaded tandem dump truck. This is my 6th full size pickup. 4th 3/4-ton 4x4 HD. None ever rode like this. I still have a '90 F-250 4x4 diesel that is softer riding than my new GMC.

 

I had two previous GM products....a '98 Chevy K2500HD Ext. Cab Long Bed and a 1994 Chevy K1500 Ext. Cab Short Bed.....both rode just fine!

 

I have been told by local dealer service departments that there is nothing wrong with this truck, it's how it is supposed to ride..... NO WAY!!!

 

Anyone that drives it says there is a problem even a local Chevy dealer, except if they are employed in some way shape or form by GMC.

 

One dealer said its a "beam shake"....for which there is no repair.

 

This truck had a window MSRP of $45,103.

 

Any thoughts, ideas, suggestions???

[mmmikkke]

Try lowering your tire pressure. Maybe you aired 'em up at 1000 miles, or maybe somebody else did. If you're running 285's, run 45 front, 35 rear.

[Nitro276]

Try lowering your tire pressure.  Maybe you aired 'em up at 1000 miles, or maybe somebody else did.  If you're running 285's, run 45 front, 35 rear.

 

<{POST_SNAPBACK}>

 

 

 

Thanks for the reply....

 

My tires have been lowered to 45 all around....the dealer lowered 'em to 50....then a buddy with an '04 2500HD Sierra said drop em even more

 

I'm running stock Bridgestone V-Steel LT245/75R16 all-season highway tires that look like they belong on a van! I'm already $2K beyond into this truck with a spray in bedliner and a Leer cap, so I'm holding off on Wrangler Silent Armor 265s.

 

Something is wrong here....when I say this truck is rough....IT'S ROUGH!

 

Why did this problem manifest itself after 1,000 miles?

[OFF-RD]

Your problem is VERY common with the new GM trucks. But your question is dead on...why did it not show up until after you had 1,000 miles on the truck??

 

On my test drive I noticed it on mine. Dealer said if I bought the truck they'd have service dept. take care of it. Well, after two trips to the dealership in the first 300 miles it was obvious my new truck was NOT going to be fixed. I test drove another one identical to it off the lot...and it was even worse than mine!

 

So the diagnosis is this...GM trucks ride like SH*T and there is nothing that can be done for them. (Except trading back for a Dodge...which I might do when my lease is up).

 

To minimize the problem...try running lower pressure in the tires. (You probably don't need 40 psi in the tires on a light duty truck even if it is a 1-ton model). Also try aftermarket shocks...some people say it helps. Good luck.

[Nitro276]

Your problem is VERY common with the new GM trucks.  But your question is dead on...why did it not show up until after you had 1,000 miles on the truck??

 

On my test drive I noticed it on mine.  Dealer said if I bought the truck they'd have service dept. take care of it.  Well, after two trips to the dealership in the first 300 miles it was obvious my new truck was NOT going to be fixed.  I test drove another one identical to it off the lot...and it was even worse than mine!

 

So the diagnosis is this...GM trucks ride like SH*T and there is nothing that can be done for them.  (Except trading back for a Dodge...which I might do when my lease is up).

 

To minimize the problem...try running lower pressure in the tires.  (You probably don't need 40 psi in the tires on a light duty truck even if it is a 1-ton model).  Also try aftermarket shocks...some people say it helps.  Good luck. 

 

<{POST_SNAPBACK}>

 

 

 

Thanks for the input.....

 

My tires are between 40 and 45 all the way around.....no help!

 

I have about 300 pounds of dead weight in the back plus a Leer cap....little help in that the shudder has been minimized a bit!

 

Overall, the truck still rides terribly!

 

For further salt in my wounds, two area GMC dealers near me in NJ looked at the truck, and basically said it meets GMC specs--I was left with feeling from one of them that I didn't by the truck from them so get lost.

 

I bought mine in VT because of the particular truck as opposed a better price.

 

The service manager at my local Chevy dealer took it for a 15 mile ride and told me that something was definitely wrong. He said he would try his best to fix it, but is being told by his area Chevy rep not touch it because it's a GMC!

 

We return to VT next week. After a back-breaking 400+ mile ride, it will be dropped off at my home dealer--fix it or give me a new one!

[MS3DALE]

This might help explain things a little for you.....

 

 

Document ID# 1844688

 

 

 

 

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.

 

 

 

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.

 

Document ID# 1844688

[mmmikkke]

Reg Cab trucks have less beam shake because nearly equal percentages of the back of the truck are forward and rearward from the rear axle. With extended cab trucks, the middle of the truck gets longer and the percentage of the truck rearward of the rear axle is less. With crew cab trucks, it's even worse. That is why the bulletin mentions mainly extended cab trucks and crew cab trucks.

 

If you want to get rid of beam shake, buy a regular cab truck.

[OFF-RD]

The odd thing is that extended cab trucks have been around as long as dirt, and this "beam shake" is just now a problem on the 99-07 trucks. Hmmm.. And...how come the Ford and Dodge trucks don't do this now? Basically, GM engineers need to go back to the drawing board and figure out a way to stop this problem on OUR trucks and offer it as a free repair IMO. It sounds like they are working on something by reading that bulletin.

[tlocus]

Hi,

I was wondering about this beam shake. Is it more of an up and down movement?

Like you were driving over small dips and bumps in the concrete? Or side to side movement?

Where I live there is only a 1/2 mile area (concrete) that it does this...could be the road though...

[MS3DALE]

Me and my buddy both have a little bit of "beam shake" with our trucks (His is an '03 Z71 Ext.cab) when we first start out driving.

Its an up-n-down movement on ours.It almost feels like we got "flat spots" on our tires until we drive for a couple miles,then it goes away.

[Nitro276]

****UPDATE****

 

I don't mind starting to reveal more details now that my Sierra is fixed!!!

 

My truck did not have the BEAM SHAKE!!!!!!!!!!!!!!!!!!!!!!!!

 

It had bad shocks. St. Johnsbury GMC in Vermont where I bought my truck put four new shocks on and adjusted the torsion bar. Problem cured.

 

Now, my Sierra does not ride like a Cadillac. Only the GM trucks built between 88-98 (and some 1999-2000) come close to that.

 

But the swaying and boat-like ride is gone!

 

I am much happier and thank you all for your input!

[69supersport]

This problem is a B@#$H!! I live in Los Angeles, most of the freeways are concrete and many times I have apologized to my passengers about the ride. Looks like its time to replace the shocks!! I have heard that this will fix most of my problem.

[mmmikkke]

Hi,

I was wondering about this beam shake.  Is it more of an up and down movement?

Like you were driving over small dips and bumps in the concrete? Or side to side movement?

Where I live there is only a 1/2 mile area (concrete) that it does this...could be the road though...

 

<{POST_SNAPBACK}>

 

 

It's an up-and-down "jiggle".

 

Imagine a tremor in your hand, like maybe you've seen in some movie where somebody shakes as they try to grab something. They're shaking at about 5 Hz (5 cycles/second).

 

Now imagine driving your truck at about 30 mph. You drive over a pavement joint where layers of asphalt cover old, old cement. The pavement joint is kind of like a negative speed bump--the pavement dips and creates a little depression across the pavement at the joint. The depression is about 2" deep maybe, for talking purposes.

 

As your truck crosses the depression the front wheels fall into the depression and then immediately come back up out of it. You feel the bump. Once. And then, half a second later, your rear wheels fall into the depression and then immediately come back up out of it. You feel the bump. But due to beam shake, you feel the bump more than once. It "jiggles" your truck 3 or 4 times before it settles out, at about 5 Hz. That is beam shake.

 

It can also happen at freeway speeds especially if the distance between the pavement joints happens to be happening at about 5-8 cycles per second. Then the frame, which has a natural vibration mode at 8 cycles per second, gets all excited and each new pavement joint builds ontop of the jiggles from the previous one.

 

It's an up-and-down vibration. Nothing side-to-side.

 

Does this sound like your problem?

[ZZebes]

Hell the pierce elevated in houston at 70mph i can actually achieve what i believe to be lift because the timing is apperantley really really close to the resonant frequency of the frame

 

I have a theory on how to eliminate it but i dont have the tools nore the gusto to pursue it right now

[billygoat]

My shake feels more like a side to side movement, and I can see the bed wiggling around in the side view mirror.