Knocking going over bumps - NOT ISS

[Yelf]

2004 Avalanche Z66 105K

I'm the original owner and have had this issue to some degree since new. Dealer greased ISS, replaced ISS, and I have replaced ISS twice. I've replaced the shocks and sway bar links with no change. Sound seems to come from driver side under feet or firewall. I've inspected front end parts, put a go pro under the hood and around various parts of the under side. Very noticeable over parking lot bumps or bumpy streets even at highways speeds. Truck still handles good.
I'm at a loss, I even took it to a dealer and they wanted to replace the ISS AGAIN. Not going to do that after putting in 2 new revision GM ISS parts.

 

 

Here is the sound

http://vid73.photobucket.com/albums/i204/tul9033/My%20Movie_zpsof4q2fpb.mp4

 

Thanks for any help!

[Brianibew]

I had a 2003 1500 that had a front end knock as well going over speed bumps or anything that would cause the front end to travel more than usual. I owned it for 10 years. The ISS got replaced twice and would fix it for a while then return. Finally decided to live with it...it never got any worse.

[Yelf]

Thanks for your reply. I just replaced the ISS last weekend hoping for some resolution, but no change. I'm convinced this is something other than ISS, but meets the TBS and others descriptions near perfectly.

[kstruckcountry]

Have you checked the torsion bar crossmember mounts? Happened on my pickup, exact symptoms you're describing.

 

Edit: Sounded pretty much exactly like your video too...

[Yelf]

I've looked at the area. I did not look at the mounts specifically, but I will now. Something that did catch my eye was one side of torsion adjustment bolts was nearly all the way in while the other side was just a few threads in.

Did you replace the mounts or just tighten?

 

Is this the repair you made? How did you identify the problem?

 

[kstruckcountry]

I was sick of the noise and layed down and started wiggling everything, I noticed the crossmember had some play. What had happened was over time, the inner metal sleeve detached from the rubber bushing. It was pretty beat up. I replaced both sides, and it's been good since then.

 

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[Yelf]

It was not the cross member bushings, mine are still in great shape. Which in one sense is a good thing since mine are welded to the frame.

I may bite the bullet and take it to the dealer. No one, including me has been able to identify the problem.