That would be the clutch throw out bearing if it goes away when you push the clutch because it puts pressure on the bearing to stop the noise.

 

There is a low frequency hum in the chassy that is normal. Mine had it from new 0 miles. There was a video from the factory that came with the new car saying that was normal. When you push the clutch in you change the harmonic and the sound quits.

Doesn't mean you have a problem.

 

I see there are a few different threads over this issue and most replies seemed to have gone to this particular thread that I am now reviving.

I never saw any definitive fix to this issue and I rarely ever post.

Just a few days ago this noise began for me as well; pretty much like OP described. However, absolutely nothing was changed on the car; no intrusive work has been done and the tires are the same as they have been since I have had it. The noise is a dull - yet pervasive - "whomp whomp whomp" which changes it's pattern depending on the speed of the vehicle and it *seems* to be coming from the rear end somewhere. The slower the vehicle is moving, the slower the noise is, the faster the vehicle is moving the more frequent the noise is. The noise itself is a lower frequency noise and does not have a high pitch nor make any 'whining' type noises.
I moved my mirrors in while driving at low speed in order to visually check the wheels are not wobbling in motion. I suspected all the usual things that have been mentioned in both this thread and all others I've seen and I am about to go out into the garage and begin inspecting components. Hopefully we can get an answer to this.

I have a modded 98' base model C5 with 130,xxx on the clock, this issue began about 5 days ago for me and it seemed that it began after I was fishtailing around with it.

Cheers gentlemen.

 

"whomp whomp whomp" without hearing sounds like wheel bearing noise. That would be my first place to look the 2nd would be cv joints on the half shaft. My $$ is on wheel bearing.

Does the noise change in a turn left or right louder or quitter? That is also an indicator of wheel bearing.

If it is just one rolling element there may be no noticeable play. You could try jacking the car and at 12 and 6 o'clock position pull / push to see if there is noticeable play. There should be NONE.

 

I did some slalom driving to check the noise under different turning conditions but it was consistent no matter which direction I turned.

So I did a little basic inspection earlier just after the post. I jacked the rear up, checked the wheel bearings for play; they were solid as could be.
I also tried moving all the joints I could reach to see if any of them had play. Nothing came from that. CV joints didn't have play and looked good, bushings are all good. I stethoscoped the diff while rotating one rear wheel, then the other. I heard no noises out of the ordinary. Although, there is no way I could rotate the tires fast enough to simulate above 20 MPH, which is about when the noise becomes audible in the car.

I'll see if I can't get a video.

 

For closure's sake, and for others that will have this problem in the future, you were right Jim.

Noise didn't change when cornering because mine was a rear right bearing. Got it fixed about two days ago. I can hear myself think while driving again and it's so smooth.

Thank you vette forum.

 

Glad you found the problem. I have only been building and driving Vets since 1967.

 

I appreciate it Jim. I'll seek you out personally next time when a search comes up with no info.

 

Notices you are in FW. We are working a move to Longview. Don't know if it will work out but working hard to make it happen.

 

Glad you found the issue with the right rear bearing. For those owners who haven't messed with their suspension, check the condition of your end links which hold the sway bar. From 97-03 (can't remember exactly) GM used plastic end links. They switched to steel because they were stiffer and more durable. If you have squeaks or creaks (especially over bumps) it may because the end links in the front and rear are toast and need replacing. It's also a good time to replace the sway bar bushings. You'll find your car handles better with better stiffness and a lot of those squeaks disappear. It's a fairly easy install but kind of a PIA to do because it's tight quarters with no lift.