Mechanics

CHEVY NEW VIBRATIONS

2003 Chevrolet Avalanche

Drive Train Axles Bearings problem
2003 Chevy Avalanche V8 Four Wheel Drive Automatic 100000 miles

Few months ago had what sounded like a rock in the break shield or input shield when I would back up in gear (only while in gear, and only in reverse). Since then the squeak has gone away, but now I have a vibration when driving forward (two events possibly unrelated).

Whole truck vibrates, really noticeable when over 55mph, and even more so when accelerating (the more aggressive the acceleration, the worse the vibration) over 55mph, makes no difference if in drive or neutral, 2wd or 4wd.

Just had new rear tires put on 15,000 miles ago, fronts are little worn 50,000 on those. Camber is out on both fronts, but that has not changed, has always been like that.

Have not hit anything or had any other drive problems. Checked the drive line, u-joints, and everything else I can visually check, nothing really unusual.

My thoughts. Transfer case, input, rear differential, or something as simple as a tire balance.

Any thoughts would help.
Avatar
Thing_2
December 5, 2008.



Check front tires for belt slip and balance. Did you check front wheel bearings? Does the seats shake more than wheel or dash?

Docfixit
Dec 6, 2008.
Without pulling the tire off, I pulled and pushed and twisted on the tire and everything feels firm. So I tried to rule out the wheel bearings.

The two spots I really feel the vibrating are the gas peddle, and the rear view mirror. I would have to say that the seats do more than the wheel. There is little to no vibration or shake in the steering wheel.

I was looking today and it looks like the inside of the drivers side tire is wearing very unevenly. I knew the camber was off so the toe was out a little, and that accounts for the uneven tread wear, but the the tread is wearing patchy, and I think that is the vibration.

However, would that account for the vibration getting worse as I accelerate? The more aggressive the acceleration, the worse the vibration, then when I let off the gas peddle, it lessens.

Like when I stand on it while moving at any speed over about 30mph, it's like I am riding a 2 stroke go cart. Then when I let up, it dies down, but does not entirely go away.

Tiny
Thing_2
Dec 6, 2008.
If tire is cupping yes that will vibrate increase in speed would vibrate more. Also two vibs seem to be occuring front and rear at high speed. Get some tires and alignment and you will feel great improvement.

Docfixit
Dec 7, 2008.
I do need new tires; And here is something new. Yesterday I pulled into a hotel for a minute, and as I went to leave (moving forward), there was a squeak and a clunk (in that order) from what sounded like the differential. I stopped and started again and same thing, a squeak and a clunk. I started moving forward again and the squeak went away at 30mph. I tried it again today, and it was gone.

I heard it last week for the first time, but just over looked it. Now it seems to be getting quit frequent.

Are we still thinking tires, or two different problems?

Tiny
Thing_2
Dec 9, 2008.
I am now thinking drive train vibration. Need to get on lift and check entire drive train before the squeak clunk leaves you stranded.

Docfixit
Dec 10, 2008.
So I was driving in today, and playing with the speed to see if I can find where this is happening more, and come to find out, it is only when I am accelerating. When I am coasting, no vibration, and it is at it's worst when I am accelerating between 30 and 45.

I drove through a tunnel today and was stopping and starting to see if I could make the noise happen, and sure enough, I did. When I am accelerating, it almost sounds like there is something rattling around my drive shaft, like a rock or something, but the sound is definattly coming between the middle and rear of the truck.

Tiny
Thing_2
Dec 10, 2008.
You found it need U-joints Classic 30-40mph vib. And on acceleration. Needle bearings bad and joint rattles the hollow shaft echos sound.

Docfixit
Dec 11, 2008.
Took it to a local shop the other day. Tell me if this sounds right, the pinion gear in the differential. It was diagnosed by the ability to turn the rear wheels a fair amount with the truck on jacks and in park.

He further said I have to have change the pinion gear set and the " differential gear set" (which are two separate items).

Tiny
Thing_2
Dec 15, 2008.
They are two seperate gears but are usually sold as a set. Ring and pinion check it out with parts house.
Wheel backlash is good test for excessive gear play but only if drive shaft is held not just in park. Grab D shaft see if it moves in park and wheels on ground. Then jack up rear and move wheel if it moves and D shaft does not then play is in diff.

Docfixit
Dec 15, 2008.
That is more or less what he said he did and sure enough, there was play.

Well, thanks for all of your help. I will post one more after this if it fixes the problem.

Tiny
Thing_2
Dec 15, 2008.
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