When do I need to replace my Porsche Rotors?

I just purchased a 1999 Porsche 911 (996) with 65k miles. The brake light is on and I am replacing my brake pads and I need to know if the rotors need to be replaced too. How do I know? I enjoy working on these myself, but never done rotors. They do have a small lip on the outer and inner edge, but I dont know if that necessarily means they need to be replaced. Please help!


Thanks!|||The main reasons to replace rotors are that they are worn or warped. If neither of these are the case, then it's a matter of if it's something you normally do when replacing pads (which some do, if the need is close enough), or because of too much pad transfer (ie, not really warped, but out of shape enough from the transfer to make a difference, and too worn of a rotor to resurface).





I think that new 996 brakes are 28mm in the front and 24mm in the back (check your manual), and the wear spec is up to 2mm... so get out the measuring calipers and if you are nearing 22mm in the back, then it's time to replace them. If you have reason to believe they may be warped, then lay a straight edge on them and see how straight they are.|||If the brake pedal does not vibrate, then the rotors are not warped, and should be left alone.


A lip on the outer edge that was not worn down by the pads, is perfectly fine.


The only time you need to measure the thickness is when you have allowed the pads to wear down to metal on metal, and have to decide if it is worth machining or not.


Normal use will never cause the rotors to wear out.