Let's inspect the disc rotor first. It should be shiny from the inside to the outer edge, and fairly uniform. Don't worry if you can see slight lines in it, this is normal wear. However, if there are any rough spots or pronounced grooves in the disc, you should replace your brake discs. Brake discs should always be replaced in pairs so that your car's driveability and safety are not compromised.
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Bad Rotor |
Refaced Good Rotor |
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Now take a look at the pads. You'll have to peek up to see them, but if you follow the surface of the disc to the top, you'll see the outside pad touching the disc. If there is 1/8" or less remaining on the pad, it's time for new ones. That's about the height of three pennies stacked.
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