I had a chance to lift all 4 tires off the ground and see where the problem is. I first started with the rear. It doesn't really vibrate at all, there is a little bit of vibration but I would imagine the weight of the vehicle would counter act them.

Then I did the front via 4wd. There is a vibration that is constant, but doesn't happening constantly. It's like dud-dud-dud-dud fine fine dud-dud-dud-dud fine fine for a lack of any other way to describe it.

It's fairly strong, but not in the floor, but I suspect that's because it's off the ground.

It can't be the engine, transmission, rear driveshaft, or anything on the rear axle. But it could be the front axle shafts, tires, wheels, or front driveshaft. It could also only exist when the vehicle is in 4wd and is in the transfer case.

Does anyone have any suggestions on where to look first?

 

I'd pull the front tires and inspect your front CV shafts.

 

It does seem like the best place to look. I will note that the suburban on both sides makes a light clicking sound when you rotate either of the front tires while off the ground. It's something like click-click-click-click-quiet-quiet-click-click....

Both does do it exactly the same and it's really not loud. I wouldn't be able to hear it while driving or with the vehicle running. My cobalt also does the same thing, but I believe it's only on one side. It has also done this since new. Does that sound like they're going bad or would you expect a light clicking from them?

 

I'd look for worn or torn boots that would let grease out or water in. how do they look?

if you spin the front end with the engine off, and tires off the ground, literally grab a wheel and spin it, what happens?

 

The boots look intact and are still fairly flexible. The undercarriage of the whole Suburban is very very clean (part of the reason I bought it).

If I grab the tire and spin it it's fairly easy to spin, although there is a bit of resistance from having to move that cv axle. It makes those 4 very quiet clicks as it goes around on both sides. Nothing appears to be messed up from an initial inspection.

 

So, I had the truck lifted up and noticed that BOTH driveshafts look bent. I also took the rear tires off and noticed absolutely no difference in the vibration.

This wouldn't be the first time GM dealerships have been less than helpful and keep making me pay for "diagnosis" and they claim it's the tires. Now I'm going to have to pay for this out of pocket where GM should be paying for replacement driveshafts.

 

why won't the cover the driveshaft if it's bent?

 

If you bought it used the PO could have been a little rough on the off-roading and bent them...why would GM be responsible for miss-use of the vehicle?
Unless you can show/prove that they were bent from the day it rolled of the assembly line its buyer beware.....

 

was this a CPO? I think you mentioned it may have been?

if it was, then they should have found this at their 'inspection' which is really just a line item to add $2k to the bill and they hope nothing goes wrong with it...

on my old Jeep (talking high school here) I diagnosed a vibration by REMOVING the front driveshaft... when I took it for a test drive... no vibration.

turns out I bent it off road...

Who takes a Tahoe so far off road it would bend a driveshaft?

Anyway, if you are handy w/a wrench you could start pulling parts... you'd lose 4WD obviously...

 

Just a quick question since I think it applies here. Is it ok to remove the front axles and drive around? I'm planning on doing my axles soon (07 tahoe), and I was thinking of doing this to see if there is any difference prior to putting on the new ones.

Though removing the front coil over shock twice does not sound appealing lol...