I changed the rear rotors of my A4 over the weekend and I did not changed the pads. This morning I noticed that there are some traces of rust where it should normally be shiny (where the pads meet the rotor). What do you think the problem is?

 

If the car isn't driven over time, this can occur.

 

totally normal - however whenever you change your rotors you should always change pads.

 

Happens with all brake discs or rotors as you guys call them, they are after all just steel.

 

ya no worries, my rotors were rusty also bc before i bought my car it sat outside in the rain and **** at the dealership, u mgiht hear some squeek while breaking but it should wear off soon, or at least mine squeeked

 

Rotors can rust practically overnight in humid conditions. You can buy rotors that are treated (cadmium plated) so they don't rust as easily. Eventually though, they all rust.

 

just drive it will go away after a while

 

It was still there after driving for a while. I will try to check the seating of the pads.

 

If it is rusty where your pads are supposed to press, either your pads are not seated correctly, your calipers are binding, or your pads are shot. Did you try to bed your pads to the new rotors?

You should always change pads with new rotors anyway.

 

The pads are still a lot of meat on it. Do you know what the thickness should be for a new pad vs. worn?