Should I resurface or replace a scored brake disc rotor?
To make the job easy (if you are doing it yourself) replace the scored side rotor. Then take it down and have it resurfaced. This way you have a spare if you need one next time. If you are having a shop do the work, it will cost just about the same because of the cost of labor. So I would just have them replace it.
If you try to resurface the scored rotor you will have to cut it thinner than 8mm to get all the score marks out of it. It’s not good to use rotors that thin….. they heat up very easily and will warp, leaving you to replace it anyway. Save yourself the headache and replace both rear rotors at the same time, along with new pads. You must be really hard on brakes if rear pads only last 20k miles. Almost all the braking effort is done by the fronts, and in a lot of cases, you can usually get 40k from the fronts, and 60-80k from the rears, unless you are extremely hard on the brakes.
