Hello,

Background: 2010 Mazda 3. I just got new tires (the old ones were cupped galore). Then a humming noise appeared. Tire person rotated tires, and hum persisted. Gets louder when turning LEFT, and is quiet, but still there, while straight; goes away when turning RIGHT. We both agreed it was the FRONT RIGHT bearing.

So! I replaced the FRONT RIGHT bearing (just the bearing, not the hub). The hum is still there, but it's cleaner (if that makes sense?).

I've read all over that it could actually be the FRONT LEFT bearing, which seems so counter intuitive as the load goes on the FRONT RIGHT when I turn LEFT.

I've had the front end up and pushed/pulled on the tires. I feel (although it could be a placebo effect) that the FRONT RIGHT moves a little bit more. I spun the wheels, and the rotor on the FRONT RIGHT hits the brake pad as the wheel spins in a periodic sense (scrape, quiet, scrape, quiet). Either the rotor is warped (no vibration while braking, not that I've notice anyways) or the wheel is spinning not smoothly. Persistent noise of brake pad on rotor on LEFT side. No play in back end either. I've never picked up a car and wiggled the wheels when it's new, so I don't know what an acceptable "wiggle" is, but since (I think) that the FRONT RIGHT wiggles more than the FRONT LEFT, I should replace the hub/bearing assembly in total.

Any thoughts? Thanks for your help.

 

Jack it up, put it on axle stands, get someone to drive the car at 60mph while someone lies under the car & listens for bearing noise, even use a long screw driver as a stethoscope.

Also jack up the rear, support on axle stands & spin the rear wheels by hand & get someone underneath to listen.

& run your hand on the tyres while turning them by hand & feel for lumps, bumps, & any other variations.

 

Anything a little safer?

Tires were just replaced and rotated twice at the shop when I first heard the noise. The noise location/amplification didn't change after the rotations.

 

Safer option is take it to your local Mazda dealer.

I've lost count of the times customers have complained about a noisy wheel bearing only for me to find a scoloped tyre.