humming (sometimes) noise after replacing pads and rotors

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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danmac01
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humming (sometimes) noise after replacing pads and rotors

Post by danmac01 »

Okay. Replaced the pads and rotors on all four wheels yesterday. actually found some useful write-up on the forum to help with the steps.

here's the issue. when driving there is a humming sound that goes in and out (it appears to be coming from the rear). the sound goes away when the brakes are applied, and is worse when brakes are just let off. the sound begins to occur after a few minutes of driving and is at complete random. It however is not loud enough when traveling above 40mph. sound could possibly dissapear at that point. I've driven about 50 miles since I changed out the rotors and pads.

I have read (dont ask where) that it may take awhile for the "adjustment" to occur with new pads and rotors. Also found that applying the parking brake numerous times may help adjust everything.

how concerned should i be? I am ruling out wheel bearings because its not all the time. also, the Mazda 3 is only a 2007 with 55,000miles.

should i get it back on the jack and take a look? or should I wait to see if the "adjustment of the brakes" occurs.
danmac01
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Re: humming (sometimes) noise after replacing pads and rotor

Post by danmac01 »

also, there are no smells of anything burning or anything, after city braking and after highway driving.
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Re: humming (sometimes) noise after replacing pads and rotor

Post by watkins »

Did you bed them in properly?
danmac01
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Re: humming (sometimes) noise after replacing pads and rotor

Post by danmac01 »

watkins wrote:Did you bed them in properly?

Do you mean the pads? I think so, they were different than the OEM, had a different spring style, but they clipped around the cylinder just fine.
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Re: humming (sometimes) noise after replacing pads and rotor

Post by 94Corolla5Speed »

I think he means did you use the proper procedure when first using the brake pads, usually it's 10-15 repeated stops from about 60-15 MPH, with 30 seconds in between.
danmac01
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Re: humming (sometimes) noise after replacing pads and rotor

Post by danmac01 »

yeah, did the stops.... from 40mph. noise started happening about 5 minutes after driving with the new sets.
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Re: humming (sometimes) noise after replacing pads and rotor

Post by theholycow »

danmac01 wrote:I am ruling out wheel bearings because its not all the time. also, the Mazda 3 is only a 2007 with 55,000miles.
That's a mistake.

Wheel bearings can present any of a million different symptoms. Unfortunately some of the symptoms are impossible to test for; you try everything else that could be the problem then you throw some new wheel bearings at it to see if that helps. The usual wobble test can tell you they're bad but it can't tell you they're good. They do weird stuff depending on exactly how they're loaded and other conditions (weight bearing only, accelerating, braking, engine braking, turning, hot, cold, humid, dry, etc).

If they pass the wobble test and the spindown test then continue diagnosing elsewhere, but remember that wheel bearings could still end up being the problem. :(
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danmac01
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Re: humming (sometimes) noise after replacing pads and rotor

Post by danmac01 »

If it's a bearing, then why wouldn't the noise have been noticable right before the pad/rotor replacement, it was only noticable immediately afterwards?
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Re: humming (sometimes) noise after replacing pads and rotor

Post by theholycow »

I suppose it could have been fine until it got disturbed by the work.
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Re: humming (sometimes) noise after replacing pads and rotor

Post by Rope-Pusher »

watkins wrote:Did you bed them in properly?
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Re: humming (sometimes) noise after replacing pads and rotors

Post by RayWillz25 »

Hey I'm having the same exact issue with my vehicle, did you ever find a solution to what was causing the noise?
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Re: humming (sometimes) noise after replacing pads and rotors

Post by ClutchFork »

maybe Alvin and the Chipmunks took up residence in the undercarriage while it sat on blocks wasting for the brake pad install.
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Re: humming (sometimes) noise after replacing pads and rotors

Post by Rope-Pusher »

I've heard wheel bearing noise that changes as the brakes are applied. I'm guessing the brake rotor pulled the hub into alignment as the caliper squeezed on it. Also, wheel bearing noise tend to be sensitive to which way you steer the car, but eventually progresses to where you hear it going straight as well.

I've also heard noise where the rotors weren't replaced, only the pads, and the new pads rubbed on the rusty portion of the rotor that the previous rotors didn't touch. This was more of a hissing noise. When I knocked the rust back from the edges of the pad contact area the noise went away.
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