what causes this on brake discs
the marks are on the inside disc of my ap discs
there pitted in and not raised,car gets used daily and is running ds2500 pads

it looks to me like the disc has rotted away and the brown bits are like rust which is indented into the disc.the outer disc is perfect.all 6 pistons move freely in the caliper

 

Looks like its been stood for ages then put to use

 

car has been used everyday since i bought it over 2 years ago.
its not been off the road for any length of time. at most its been stood for 12-15hrs when i finish work one day to using it the next day for work.but generally i use it at night aswell so most nights its lucky to be sitting 10 hours overnight.

 

It looks like the disc surface is glazed, some of the glaze has come off, revealing the rusty disc surface underneath. I had a set of rear discs do it when running DS2000 pads. It took ages to get the glaze off with a flap wheel, only for me to discover a crack on one disc.

 

would getting the brake disc skimmed solve the problem?

 

What diameter are those discs?? They don't look like AP rotors to me but maybe the photo is deceiving me!

 

must be poor quality metal then for them to rot like that if its used daily how deep are the pits? you may have to bin them for new!

 

there the 356mm x 32mm ap's
genuine ap kit not the ggr ones

heres a full pic