There has been a lot of talk about lightweight rotors. Some rotor manufacturers have been taking steel out of the plates and fins to keep their costs low.

For technicians, these lightweight rotors can result in comebacks due to noise and overheating. For consumers, it could be a serious safety issue.

Here is a great article from Import Car Magazine on the Topic

Tech Tip: Lower Mass Brake Rotor Causing Noise, Fade and Failure Problems