Rhythmic grinding noise 2001 1500

[aspenpup]

Re 2001 Suburban 5.3 2 wheel drive 160k miles

I am getting a rhythmic grinding noise that seems to be consistent with the rotation of the wheels. It sounds very similar to a brake pad that has worn down to metal and hitting a warped drum but depressing the peddle makes no difference in the sound.

I inspected the pads and they looked fine. I took the burb to dealer to fix a trans leak and asked them to figure out the source of the noise. They told me it was my front hub wheel assembly and they wanted to replace both for $950. I told them to hold off and I ended up purchasing 2 hubs for $189 on eBay and replaced myself in 1 hour (pretty easy job). That did not solve the problem, I am VERY thankful that I did not have the dealer work on this.

While doing the hub replacement, it looked like there was the possibility of one of the pads wear sensor (metal finger thing) was close to hitting so I went ahead and replaced the pads and turn the rotors. After this brake replacement (front only), I still get the noise.

I am running out of options. Any suggestions? One guy suggested the drive shaft but doesn't that turn faster than the wheels? Seems like the sound would be higher revs but my sound seems to tied to the rotation speed of the tires (if rolling slow, the sound is slow; moving fast, the sound is fast).

Anybody have some diagnotics steps I can take to isolate? Seems like the next step is to look towards the rear. What do I look for? I have no experience with working on the dif so I hope I do not have to go there (i.e., big parts = high $$)

[aspenpup]

Still a mystery. I had a friend sit in back seat to see if he could determine the source of the noise. He thought it sounded like a tire separating yet could not determine which side. Willing to explore this ideal, I substitute the back wheels with some spare wheels I happen to have but the noise did not go away.

While removing the wheels, I tried to see if there was play in the rear wheels. I did not detect any 'wiggle' but I was able to 'pull' the wheel out about 1/4". I would not exactly classify this as 'loose' to point to a bearing problem but I was concerned about the movement. When I went to the other side, I detect the same movement when I pulled on it but it probably was only 1/8" of movement.

Anybody care to comment on this type of movement? Since both sides are doing it, I have a feeling that this is normal but welcome any comments.