Strange vibration/reverbration - slight drvshft play. (video inc.)

[BA.]

I just noticed today that I somehow posted this in the wrong vehicle year forum. (smack forehead)

I've been plodding away at trying to pinpoint the cause of my 2003 Tahoe Z71 vibration.
It's most noticeable between 25mph and 60mph where it starts to trail off. Keeping 70mph+ seems a good alternative for now. It also causes a bit of a resonance between 40mph-55mph. Sort of a WAH-WAH-WAH low resonance.
I've owned the truck for just over 2 years / 20,000 miles and this just spontaneously started about a month ago when we had a brief cold-snap of 15-20 degrees. Nothing new for this truck though.

After hoping and checking on the easier things.....
-New tank of fresh gas. Too easy.
-Spark plugs and wires checked.....
-Happens in OD,.....and 3rd gear and 2nd gear at the MPH's noted above.
-GOES AWAY with the very slightest of deceleration! Consistently, no matter the speed where decel is started.
-Slightly less noticeable under heavy acceleration over moderate acceleration.
-Happens under steady-state speed at the speeds noted above.
-Wheels & Tires removed and balanced and checked for separated belts. (Firestone)
(only 1 year, 10k miles, stock sz)
-added a can of transmission (converter) anti-shudder.
-happens in either 4-Auto or 2WD. (4WD button function inoperative for long time)
-have not had opportunity to swap wheels with anyone.
-was going to swap rear U-Joint but the shop had driveshaft out and said it didn't need it.
when on a lift, the rear of the driveshaft was rock solid, wouldn't move.
-The rear driveshaft yoke where it goes into the transfer-case moves a little and clunks a little.
IS THAT NORMAL? The U-joint itself seems fine and the noise seems to be inside the transfer case.


So, here is the VIDEO, even though it's as much about the AUDIO!
23Mb - may take a few seconds to download.
http://www.media-swap.com/2003_Tahoe_driveshaft.mp4

 

[SLCHOE]

Sounds like a wheel bearing.

When it makes the noise is it front or rear of where you sit?

Now you can elimanate half of the vehicle.

Drive the truck down a straight empty piece of road and get up to 45 mph. Then swerve left and then right and back again. If you hear the noise when you turn the wheel to the left, it's the right wheel bearing. If hear the noise when you turn the wheel to the right it's the left wheel bearing.

Just as your body is affected by inertia and wants to go in the opposite direction as you turn the wheel, the vehicle is also putting more of it's weight on that same side. If a bearing is bad, you will know it.

 

[tlang]

I agree with slchoe. I would say that amount of play out the front of the DL is pretty normal. Definitely sounds like a wheel bearing. Can you have a passenger sit in the back seat to get a second opinion if its in the front or rear?

If its hard to pinpoint the noise, you can put it on a lift, put it into 4wd, run it at about 40mph and put a stethoscope on each bearing. Just had to do this on my wifes Denali, she flipped when I told her she was going to drive it in the air.

 

[BA.]

Thanks for the replies.
Getting the vehicle up in the air and in gear did seem like a logical next step so I will definitely be doing that.
I should have mentioned that the reverberation sound is really in a narrow mile per hour band around 45-55mph not constant.

It may very well be a bearing, it just doesn't sound like any failed bearing I've heard before. I think getting a 2nd person in the truck is a great idea, I'll try to get that done too.

I have not noticed any change in the vibration or noise when turning left or right yet.




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[tlang]

Keep us updated, post a fix when you get there.

 

[SLCHOE]

Thanks for the replies.
Getting the vehicle up in the air and in gear did seem like a logical next step so I will definitely be doing that.
I should have mentioned that the reverberation sound is really in a narrow mile per hour band around 45-55mph not constant.

It may very well be a bearing, it just doesn't sound like any failed bearing I've heard before. I think getting a 2nd person in the truck is a great idea, I'll try to get that done too.

I have not noticed any change in the vibration or noise when turning left or right yet.




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If it's between 40-60 mph i'd look at the wheel balance and then drive-line balance.

 

[BA.]

UPDATE: We had some 65-70/degree weather and the vibration is basically gone.
Recall that this vibration started when we had a plunge to 15 degrees or so.

I thought I've heard that separated belts can cause this. Is that a possibility given the change with temperature?



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