grinding/buzzing noise when driving

[CrashTestDummy]

We've been making some longer trips in the car lately, and at highway speeds, I'm hearing what seems to be a grinding or buzzing noise that seems to me to be coming from the front of the car. The noise varies with vehicle speed, so should be something front wheel or rear drivetrain related. The car tracks and handles fine.

I've jacked the corners off the ground, and given the wheels a check, and all 4 corners feel smooth and tight when hand-spinning. I even jacked the back of the car off the ground and ran it in gear a bit, but still heard nothing.

Is it possible we have a bad hub bearing that's bad enough to be noisy, but still feels smooth when spun and doesn't have any play in it? I've led a sheltered life, and haven't ever experienced issues with these self-contained hubs. Thanks for any pointers.

[Sanford]

Does the noise change any if you turn the wheel a little while driving? If there is a bad spot on a race, it may unload it enough when turning to make the noise change or go away. Then it is a guessing game as to which side is the bad one.

[CrashTestDummy]

No notable change in noise when I turn. I may 'rotate' tires this weekend, going front to rear and rear to front, to see if that changes anything. With that, I can also get closer to the hubs/calipers/axles, too.

[CrashTestDummy]

Right side tires swapped front-to-back. Checked in and around both hubs and no oddities seen. The front hub spun freely with no noise or wobble. I didn't spin the back hub, as the left side was still on the. ground, but last time I had the back end off the ground, everything felt smooth and no noises.

So far, no notable change in sounds, but I've only been to about 45 MPH.

[JoeR]

Although this sounds crazy, try it anyway. LOL.

If it's a bad wheel bearing, it's unlikely that you can feel it by shaking the wheel. So jack the wheel off the ground. Put one hand on the strut spring and spin the wheel. If the bearing is bad, you'll feel "roughness" in the spring as the wheel spins. If it's bad enough to be audible, then it's bad enough to be felt in the spring. You'll be able to feel the difference from one side to the other.
If you can't feel it in the spring, it's unlikely that the bearing is bad.

I know it sounds goofy, but it's free to try.

Joe

[CrashTestDummy]

Thanks for the tip. I'll try that. Yes, it's bad enough I can hear it, even at ~40-45 MPH. Gets quite loud on the freeway!

[CrashTestDummy]

Although this sounds crazy, try it anyway. LOL.

If it's a bad wheel bearing, it's unlikely that you can feel it by shaking the wheel. So jack the wheel off the ground. Put one hand on the strut spring and spin the wheel. If the bearing is bad, you'll feel "roughness" in the spring as the wheel spins. If it's bad enough to be audible, then it's bad enough to be felt in the spring. You'll be able to feel the difference from one side to the other.
If you can't feel it in the spring, it's unlikely that the bearing is bad.

I know it sounds goofy, but it's free to try.

Joe

Son off a bisch!! Put the front end in the air, and gave each wheel a spin while holding the spring. Sure enough, I could feel some rattling in the spring on. the front right. The front left felt smooth. Replacement Delco unit has been ordered from RO. We'll soon verify this theory!!

[JoeR]

Sounds like you're making progress. I spent a few years as a Chevy Tech, but more importantly, I did stay at a Holiday Inn Express last night, LOL.
Joe

[Pursuit]

Joe,
Great observation on the NVH that is caused by mechanical items in motion. Makes sense that the springs would amplify the roughness of the bearings. Thanks for sharing your insight!

Maurice

[JoeR]

Joe,
Great observation on the NVH that is caused by mechanical items in motion. Makes sense that the springs would amplify the roughness of the bearings. Thanks for sharing your insight!

Maurice

Ever since GM started making Front wheel Drive cars in the 80s, I've never been good at telling which side wheel bearing is making the noise. This method has made me look way better at it than I am. Now that I have a bunch of hearing loss I REALLY appreciate being able to do it this way.

A short while ago I got to play with an acoustic imager. It'd be a seriously helpful tool to use on cars, but the $15k price tag makes it not worth it. You can see the sound in the springs with it, and in the wheel too, but you'd never be able to feel it there. It's also pretty impractical when you have to drive the car to reproduce the noise or harmonic. A chassis ear of some sort is still the better tool for cars.

Joe