How can I tell if I need new brake pads? My car is squeaking when I brake so my first guess is that it is the pads. Do I have to take them off to read them or can you just look at them with an s2000? Also, How can I tell if I need new callipers or rotors? I have been told that my rotors are supposed to be smooth but there are definately scratches. Unfortunately, I cannot afford to replace them right now. How much does the fact that it is not perfectly smooth really affect the brakes?

 

if you remove the whell you can see the thickness of the pads.
the service limit IIRC is 1.2 mm.

small groves on the rotors are OK.
there is a service limit on the rotor thickness - check service manual.