Quote Originally Posted by jyh888 View Post
Question - my mates STi recently bought new DBA4000 rotors and he is getting brake shudder after the track day, could they possibly be warped?? How can you tell and is it advisable to get them machined or will it affect the heat treatment on the rotor?
Were the rotors brand new just installed when he ran them on the track? Or have they been driven around with for a few thousand km? The DBA4000 needs a few thermal cycles to avoid warping, hence the reason why it has temperature indicator marks on the edge of the rotor. Heat treatment is throughout the disc, so machining it shouuldn't affect it. Get the place to check the runout (amount of warp) before he machines it.