04 suburban loud noise

I have a noise that has been driving me crazy for a week now. After some investigation I have discounted a few things. To sum up the noise, it seems to be coming from under the vehicle, maybe the passenger rear. It sounds kinda like a jack hammer and it is loud. People on the street can hear it well! There is no consistency in it. I do not here it standing still and it only appears when I am driving. The speed does not matter. While driving, it will come and go, it will last from 5 seconds to up to 30 seconds. While driving along, it starts, then stops abruptly without dying down. The speed of the "knocking" will follow the speed of the vehicle. If Im going slow (20 mph) it will knock at a slower pace, thus going 65, it is 2 a second. There is nothing loose, I have ruled that out. Although it does sound like something loose and hitting. I can feel it slightly on the floorboard under the pedals and passenger side. I have to believe it is the rear u-joint? but that was replaced 2 years ago, and I have never heard of a u-joint making this noise. Please, please help! Thank you.:banghead:

Pull the driveshaft and inspect the u-joints. It sounds like you are describing a rotatoinal noise, if so, inspect anything that rotates with vehicle speed. It sounds like a rapid type of noise, so I'm leaning to a u-joint issue.

Checked u joints, all is well there. Lifted vehicle before that and let rear wheels drive for thirty minutes and nothing. Couldn't get it to make noise!

Have you had any AC problems? That sounds like the AC belt tensioner going bad. It might sound like from the middle or rear of the vehicle, but actually is coming from the front of the vehicle.

Found the noise. It ended up being the right rear parking brake shoes. The pad had come off the shoe and the show itself was loose banging on the inside of the rotor. Replaced shoe and cylinder. Problem resolved. Thanks to those who tried to help!

Found the noise. It ended up being the right rear parking brake shoes. The pad had come off the shoe and the show itself was loose banging on the inside of the rotor. Replaced shoe and cylinder. Problem resolved. Thanks to those who tried to help!

make sure you have the new shoe hold down clip. this keeps the shoes from moving as your operating the vehicle. the originals on my 2000 caused this to occur.

make sure you have the new shoe hold down clip. this keeps the shoes from moving as your operating the vehicle. the originals on my 2000 caused this to occur.

Do you think the light rotational "pinging" I am getting from the right rear of my 2005 might also be caused by this component? I had the entire rear e-brake cable assembly replaced about 10K ago, and had no issues until the last hundred miles or so. No marks on ther rotor indications of main brake wear.

Do you think the light rotational "pinging" I am getting from the right rear of my 2005 might also be caused by this component? I had the entire rear e-brake cable assembly replaced about 10K ago, and had no issues until the last hundred miles or so. No marks on ther rotor indications of main brake wear.

I would remove the rotor and inspect the inner park brake drum. if the drum shows signs of wear [clean/shinny] then the clip is not working.

the shoes should be difficult to move fwd/aft .

replacing the shoes the clip need replacing also.

removal of both rotors and compare them also ..you should not have any wear on these park brake shoes if so the clip is wrong/defective or your driving around with the park brake on..

also check that the pad clips on the calipers are not touching the rotor. this can occur/ not properly set into position/bent.