Check the wheel liners and other plastic bits that are in the airflow. Sometimes these get loose and vibrate in the wind ant particular speeds, e.g., pan shrouds, belt guards, etc.
P.S. Try changing the tire pressures, e.g. a short test run at max tire pressure printed on the sidewall. If you get a major change in the sound with a temporary change in tire pressure, it's likely the tire are the culprit, even if you have tried two sets.
Hey everybody, I started a thread called "growling noise" to see what the responses would be and at the same time I figured I might as well check out old threads and came across this one. The problem here sounds similar to what I'm experiencing with my 2000 ZX3. Tires are Michelin Destiny's with approx. 15,000-20,000mi., both on front are wearing evenly. The noise started 6-8mos. ago, a lite growling noise, kinda like the noise 4x4 tires make. Now its deeper and louder, around 60mph I notice a slight vibration in gas pedal and steering wheel. Replaced right(passengers) side axle after car broke a spring on drivers side and the dealership noted on the paperwork that the center support bearing and left wheel bearing were bad. Talked to tech that worked on my car and he said it was one or the other, after hearing the growling noise when he test drove the car. Checked wheel bearings, could not feel any play, felt smooth when spinning tire. So I went with the center support bearing going bad. Pulled old one out, compared the feel of spinning the old compared to the new. Did not feel smooth, felt kinda dry. I thought cool, this is the culprit. It seemed to quiet down for a while, but the noise is back and now it changes pitch and loudness when I turn wheel to the right. When I turn to the left, it is unchanged from the noise it makes going straight. I have checked the bearings on both sides since the noise returned, still the same. Doesn't seem to be getting any hotter than normal.
Downloader, you said if the noise gets louder on one side, its the wheel bearing. Have you had this same experience and did changing the bearing on the side that makes noise when you steer in that direction solve the problem? Just trying to get some personal experiences and solutions before I waste money(and time) trying to figure this thing out. Thanks, Mike
I did the right - left turn test and found it to be the bearing on the opposite side of the turn that was loudest. Loud when turning right = left bearing. Vise versa...I could tell it was the rear so i went there first. Right rear bearing was toast already. I had the same vibration issues as you describe above.
2000 Zx3 too. When you get the new one - make sure you pack the hell out of it with grease.
Ford just puts a dap of whale snot in there and thats it.
My bearing was DRY when I cracked the OE one open.
I did not do the other side and I have not had any issues since.
Yes my car does a a very low humming noise at 70 but as soon as you let off the gas it stops. The cat converter bracket was broke we changed that and it got a bit better. My guy thinks it is in the exhaust because of the fact it stops when you get off the gas and since it got a bit better when the bracket was fixxed. please let me know if you get it fixed.
I'm still trying to figure out what my noise is. I checked the rear wheel bearings(grabbing top & bottom of wheel, pushing & pulling and then spinning wheel), no movement or running hot, everything seems ok. The noise I hear isn't a humming noise, its a growling noise comparable to 4x4 truck tires with deep lugs(tread) running down the road. It starts at around 25-30 mph. and gets progressively louder up to 60-70 mph., also developing a vibration in the gas pedal with a slight shimmy/vibration in the steering wheel. I have a man. tranny and thought maybe that is where the noise is coming from, but when I push in the clutch and coast, its still there. Changed fluid in tranny when I replaced seal/axle shaft on the right side, it seemed a little dark, but didn't smell burnt. It also sounds like it might be coming from drivers side but its hard to tell. I'm not sure if this may be the cause, but I'll run it by you guys and see what you think. When I replaced the axle on the right side, I had the car on jack stands, letting the front tires hang, started the car, run it through the gears to see if the noise was still there. Didn't run it for very long and it seemed like the noise was gone, but then it came back a few days later, soft at first and finally where it is now. The service CD I have for the car said not to free wheel the car with the suspension past a certain degree of angle/pitch or damage to the CV joint will occur. I had mine dangling when it was on jack stands(stupid me, read this after the fact). Think its possible that I damaged an already ailing CV joint?
I don't believe its any of the plastic panels or the cat convert. bracket, because its there from low to high speed, push the clutch in and coast, makes no difference.
I'm still [?|] and ready to[whip] something or somebody(nobody in this forum, of course)  .