Re-arcing
Before 1984, it was common to re-arc brake shoes to match the arc within brake drums. This practice, however, was controversial, as it removed friction material from the brakes and reduced the life of the shoes as well as created hazardous asbestos dust. Current design theory is to use shoes for the proper diameter drum, and to simply replace the brake drum when necessary, rather than re-arcing shoes.
Read more about this topic: Drum Brake