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Car: 2006 Saturn Ion, front wheel drive.

Symptoms

A steady friction sound, like loud road noise (not a scraping, not metallic), comes from the front end, audible starting around 20 MPH, and getting louder with increasing road speed (unaffected by rev count). The sound basically goes away when going around a right bend (even a small turn of the steering wheel to the right drastically reduces the sound), and gets louder when going around a left bend. Turning the engine off while traveling has no affect on the noise. With the car parked and in neutral, no noise is generated.

I put the front-end up on jacks and removed the front right tire. With the car idling in 1st gear, the left tire turned but the right didn't. The front end would still generate the noise. I removed the brake, and the hub + rotor (secured with the lug-nuts) would turn in 1st with the gear idling. Also, no noise generated. The hub wouldn't wobble, and turned by hand without any noise and felt smooth (no gritty/sandy feeling). The hub would turn with less than around 1 ft-lb of force (checked by setting a click torque wrench to 1 ft-lb & placing it on the hub nut; it would turned the wheel before clicking).

The brake pads are still quite thick, and were replaced professionally about 1.5 years ago, along with the rotors.

Steps Taken

  • Swapping the front wheels had no affect on the noise.
  • I tried out a new hub, and (with the wheel reassembled) the sound remained.
  • In the process of putting the break back on, I recompressed the piston (with a c-clamp) and drained a little of the break fluid (and then topped off the reservoir), which ran clear.
  • I cleaned and lubricated the brake pad clips (they were quite dirty). This may have decreased the noise at faster speeds, but it's still quite present (especially when bearing left). (I'll likely end up replacing the clips.)

From what I can see (and have read), the calipers are auto-adjusting (which is to say, not adjustable).

Questions

What other diagnostic steps can I take? Given the above information, what are the likely culprits, and what can be done?

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  • This sounded like a wheel bearing the entire question until I read that you checked it. Very strange. Have you tried checking CV on the bad side? If not swap the two front wheels and see if it moves to the other side, perhaps it's a wheel/tire issue
    – Chris
    Commented Dec 6, 2020 at 22:22
  • I thought it was the bearing at first, too. Swapping the tires was the first thing I did (as a quick, no-cost check); I hadn't bothered mentioning it as I figured the detail of the noise existing with the car jacked up made that a moot point (I'll add it now). The CV on the left side definitely needs replacing, but (since the noise went away with the right brake off) it seems unlikely to be related. Still, I'm planning on replacing both front axles when the weather gets better.
    – outis
    Commented Dec 7, 2020 at 3:28

1 Answer 1

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Sounds like the only remaining possibility is the brake dragging. The caliper piston may be failing, or the pads themselves may be sticking. The pads basically float along a low-friction surface (those metal clips that usually come with new pads that snap onto the caliper). If those clips corrode, go missing, or otherwise lose their low-friction properties, the pads may not release fully.

Also check the caliper pins which allow the entire caliper to float and adjust as the pads and rotor wear down. This can cause a similar symptom if they do not move freely and easily.

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  • The piston was my primary suspect, until you mentioned the pins. There are 2 screws that attach the caliper to the bracket. Are the pins what these screw into (under small rubber boots)?
    – outis
    Commented Dec 7, 2020 at 3:32
  • That's right, the rubber boots keep grime away from the (hopefully) lubricated pins.
    – masospaghetti
    Commented Dec 7, 2020 at 3:34
  • Replacing the pins (one of which only slid out with great effort) took care of the road noise & wheel not turning while idling, but now I also have a scraping noise from the middle of the front-end, even when the brakes aren't connected. I think it's a different issue, though, so more troubleshooting (and another hub-swap), then another question.
    – outis
    Commented Dec 24, 2020 at 1:14

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