Humming Sound Similar to Wheel Bearing, but Possibly Not
 

Good afternoon all,

Here's a rundown:

2013 Scion FR-S, about 166k miles, mostly smooth highway miles, manual of course
South Florida, so far South that Broward is considered Central Florida
recently started making a humming noise at 40+ MPH, speed related
swayed left and right while driving, sound does not favor a side
no play in wheel, suspension is tight, no rubbing
recently did SS lines / rotors / pads, however no rubbing or other issues
diff and trans fluid changed 10k miles ago w/ new TOB
I do run spacers, furthering my worry of the wheel bearing
tires seem good, even wear, no high/low spots, still fairly soft
never tracked, but did go down an 1/8 mile a few times and I do like taking turns a little quicker than I should

Bottom line to this query I guess: is there anything that would cause similar noise to a bad wheel bearing? Any known issues with the trans/diff/shaft that could cause this noise?

Any help is appreciated. I'm fairly good with cars and am always on top of maintenance. Other than the sound, the car drives like new and has never given me a single issue.

Welcome, Boosh. I hear ya. These can be tough. In my experience, weird tire wear can mimic shot wheel bearings. Sometimes tire noise doesn't change in response to changes in load.


Maybe something behind transmission is going by way of Sugarloaf or further.

Maybe you've got a snapped belt in one of your tires? Hit any hard bumps lately?

Here's a photo of a tire I switched for my father in law. "There's a loud hum" is how he described it. Sorry for sideways photo, this uploader sucks ass

Tire wear is kinda what I was thinking too, but the tires seem pretty good, alignment is on point. Tires are about 18 months old I think, so they're a little old, maybe slightly dry tread is causing the sound? I have new tires and wheels to be put on this coming week, so i'll update if that fixes the issue, but still tinkering to see if I can find any other culprits.

Come to think of it, rear end noise comes and goes with changes in load pretty dramatically. You'd have figured that out already. Good luck. Keep us posted.

Could be a lot of things unfortunately. Diff bearings maybe? The pinion bearings would be more obvious under accel or deccel. If its carrier bearings it would be a steady sound. Prop shaft support bearing is another option. That is a hard one to isolate.

Did you put slotted rotors on with your recent brake work? Sometimes that can create a hum as the pads rest against the rotors.

Yeah, slotted rotors, but I think the sound was there before. I could be wrong though. Sound is not dependent on load, it's consistent with speed only.

Anyways, new tires and wheels feel great, but sound is still there. Sound hasn't gotten worse, but hasn't gotten better. For now i'll ride it out assuming it's a muffler bearing or paranoia of the car falling apart.

Thanks for yalls assistance. If I ever do find out what it is i'll be sure to post it somewhere.

Did you ever find out what it was? I've got a similar issue.

Same sounding issue on my 2014 if anyone has fixed this, I would like to know.

OP hasn't logged in for a couple years. Can you record the sound or describe details?

When driving could hear a new kind of light rumble or vibration sound throughout the car that was not the usual car sounds. Hard to locate it in any one spot from inside. Noticeable on highway speeds if I recall correctly and noticeable when driving around 40-50mph steadily on back roads. Some might miss the sound, but I could tell it was not usual. The sound would only change with rolling speed change, not if I changed gear, etc. 100% tying it to the speed of something. Similarly, no issues with wobble test of the wheels.

Ultimately, I replaced both of my rear wheel bearing assemblies and the sound went away so it seems like that was what the issue was.

Side note, a couple years prior, a Subaru dealer 'service' center (which damaged my car in another way as well), come to find out also had tightened one of my lugs so hard that I had to get a new one when I was getting the wheel bearing assemblies replaced at a different service center this time, and that (memory's a bit fuzzy now on this) may have begun to damage my rotors in some way. I also got the rotors replaced at the same time as getting my wheel bearing assemblies changed. Not sure if either of those were related, but I recall all the research and testing I and the technicians did pointing to the wheel bearing assemblies being the main issue causing the sound.

When I lifted the car up and hand spun the wheels, the suspect wheel had a wss wss wss sound and a 'knocking' sound maybe like a muted / softer sound like what you hear in a paint spray can when shaking it / the mixing ball.

I have some videos of all this, but my old YouTube account for this stuff is lost to me so I couldn't upload it.