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Discussion Starter · #1 ·
I had new tires put on my car yesterday. The owner told me that they also checked my brakes and alignment. Everything is good. So on my drive home I started to slow down to turn down my road and noticed a thumping noise coming from the front passenger tire. I drove home and it continued to make this noise when I started to slow down, but once I pressed down on the brake pedal alittle more the noise would stop. I took it back to the shop, they took it for a drive and said that something it wrong with the brakes. Now it didn't make this noise before I took it there. I'm leaving for vacation next Saturday and I'm taking my car. Any thoughts on what might be going on?
 

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2011 Kia Optima
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Probably brakes if noise dies when applying brakes, but if still making noise, put the front tire(s) on the rear and see if the noise changes. If it does, tires, if not better check the brake system.
Why it would change after new tires installed, really don't know unless they looked at the pad thickness with a brake package sale in mind.
 

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2012 Black SX Prem. & Tech.
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Here's a wild theory: somehow your brake disc received a bend, bump, or wave in it when your tires were serviced. So when the wheel rotates, the disc has a little jiggle every rotation, and bumps into the brake caliper or brake pad, to make them shift side-to-side once per rotation of the wheel. When you press the brake pedal, the noise would go away because that removes the air gap between the brake pad and the disc, so they don't bump together, and instead the caliper just shifts side to side on the pins.

Do you know if the sound is periodic and the rate increases with speed? Do you feel any pulsing or warping in the disc when you brake?

Now, the disc could have been "flattened" on the edge, like having the bare disc fall onto the ground and making a "flat" spot in the disc that is thicker, so it's not warping back and forth, but making a thick spot that bumps into the brake pads.

You can remove the wheel, and look closely where the brake pads meet the disc. Then rotate the disc and see if the disc weaves closer or farther to the pad as the disc rotates.

A similar approach is used to diagnose and fix bicycle rims that are bent out of true, where you see the disc moving back and forth while it spins. See this bicycle video tagged to the time 1:27:



Conspiracy theory time: the shop wanted to get more money from you by replacing your brake pads and discs, but you declined the brakes and just wanted the tires. So, while working on your tires, the shop "accidentally" hit your disc with a hammer to put a bend in it or a nick or flat spot to make this noise.

More likely: your discs are worn too thin (you can check this by measuring how thick the disc is), and susceptible to warping, and you happened to brake heavily by habit, and this is just the first disc to warp enough to cause a noise.

Totally speculation on my part to try to spark more ideas for looking at the components and seeing what is making the sound.
 

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Discussion Starter · #5 ·
I still have the noise, but its slowly going away. My boyfriend and I pulled the tires off and saw what looked like grease on the rotor. We tried to wipe it off but no luck. I took my nail across one of the lines and it caught. So here is what we are thinking......they purposely scratched my rotors so I would get new ones. Well their loss car is under warranty. Hahaha
 

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Doubt that they would scratch the rotor(s), a lot or work to do that, and if they did it still wouldn't cause a thumbing noise. As far as warranty, certainly depends on mileage as brake components are normal wear items.
 
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