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Discussion Starter · #1 ·
Hi everyone, just bought my son his first car for graduation, a 2015 Optima Lx with 44k miles on it.
I have two questions to ask , first one is about brakes. The brakes make a slight scrubbing noise , especially audible at slow speeds, so , I changed all pads with platinum pads even tho the ones on it looked fine and there was no change. Still makes light scrubbing noise. Rotors maybe? Or will certain brand pads work better?
Second question is this, when driving last couple times , the windshield will frost up at bottom some like when defroster has been left on cold for too long. But the defroster is not on. It doesnt go away once it starts. Anyone experience this ? Ideas? Thanks to all.
 

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2012 Kia Optima SX
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For the brakes, do you hear it more from the front or back? Do you notice any vibration in the steering wheel under braking? If the noise is more from the back, your emergency brake may need adjusted, it uses shoes inside the rotor as a drum and it may be rubbing. If there is vibration, you may need new rotors or your rotors to be machined.

For the frost, I got nothin'.
 

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2012 Black SX Prem. & Tech.
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Can you provide more details on what the scrubbing noise is like?

Another possibility is rust accumulation on the rotors, which is to be expected when there is rain. It scrubs off and goes away with normal use.

Does your scrubbing noise ever go away? Does it happen when you are staying still? Or just moving? Does the pitch change with speed?
 

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2015 Optima SXL
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I used to work at a brake shop and have seen the inner splash shield bent enough to contact with the rotor and give a scraping sound. For the rear this is easy to test as you just hand spin them while jacked up. If you have manual E brake this can also test what im_totally_working suggest for the inner drum pads rubbing. It's a pain to get to the rear rotors off so watch a video to help in removing the control arm bolt and shock bolt to get access to the blocked caliper mounting bolt. You will need two jacks. For the front you can chock the rear wheels, jack up one front wheel at a time then put the car in neutral and hand spin to listen for the rubbing.

For the frosting windshield this is due to the system not closing the hatch tight enough to stop cold air from escaping out the dash vent. Try cycling the venting from dash to front many times and see if it frees it up some. Only other option is get into the dash and check the seal. May have kinked or smashed flat to allow the air escape. I sure hope that's not the case as getting in there I bet is a real chore. I had a Chevy Volt that did the exact same thing and drove me crazy! I hate to admit but I actually taped over the dash vent until I eventually sold the car.
 

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Discussion Starter · #5 ·
Hi, yes the scrubbing noise only happens when you press brake pedal, its not really loud and actually its not hardly audible at all outside car , just i cabin. Its definitely when brakes are applied.
Its not worn pads , not wear sensor. Rotors are smooth but didnt know if could be back ones are warped. No real shaking when you brake hard so guessing front ones are ok.
Didnt know if it was normal in these cars to hear a little brake noise or are most dead quiet?
 

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Good description. I do hear some very slight rubbing on mine so probably just something to get used to. I know KIA uses Ceramic pads with a diagonal groove which amazingly helps keep sound down, did you replace with that type?
 

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Discussion Starter · #7 ·
These had vertical groove as did the ones I removed from it. Its really not that bad , just little annoying, the dang frosting on windshield is more annoying. I figured kinda what you said, the defrost door not closing up all the way.
 
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