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I recently purchased a car with 135k miles on it and I have no idea when the brakes were last replaced. I've done work on my cars before but never have changed the brakes, so I'm not sure how to tell if the brakes or rotors need to be replaced. What are the indications that the brakes or rotors are bad?

Also, a slightly different but somewhat related question: when I lightly used the brakes I hear a sort of "click click click" or "clack clack clack" noise that seems to come from the left front brake. It doesn't happen if I brake hard. What does this mean?

Thanks for your advice!

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2 Answers 2

up vote 5 down vote accepted

Usually you check for the following:

  • Brake disk thickness. All disks have a minimum thickness and when they reach it they need to be changed. Normally the minimum thickness should be marked on the disk itself, but you should find it stated in the workshop manual for your car as well
  • Same for the brake pads, they should exceed a certain minimum thickness
  • You also should check the condition of the friction surface and check that the whole pad sweep area is in good condition and not corroded. On some cars the calipers can corrode and you suddenly get the pad applied to only one side of the disk, for example
  • Condition of the brake fluid. Normal fluid[1] should be roughly the color of cheap honey (light amber), if it's dark you want to change it. In fact, you should normally change it every two years anyway as it's hygroscopic.
  • Check the condition of the brake hoses. Unless someone already fitted braided hoses, check that the rubber on the hoses isn't cracked.

All that said, if you haven't worked on brakes before it might be better to either have a pro work on them or get someone who knows what they're doing to help you. Brakes aren't really something you want to have fail on you...

[1] There are a couple of exceptions like the ATE blue stuff but people who put that sort of fluid into their cars tend to remember when they worked on the brakes last.

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Thanks for your answer! Is a "Brake disk" the same thing as a rotor? –  Nate Apr 19 '12 at 0:10
    
@Nate, yes, disk = rotor. –  Bob Cross Apr 19 '12 at 0:26
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Perhaps this can be a bit of help:

Brake squeal that goes away when you apply the brakes and comes back when you release them is the wear indicators meaning that your brake pads need to be replaced.

Source: Squeaky Brakes: How much of a concern are they? answered Mar 21 '11 at 3:03 by Larry

Also this video provides some good information on what to look for: http://www.ehow.com/video_5225926_car-brakes-need-replacing.html

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