Why are secondary brake linings longer and thicker than the primary linings?

Prepare for the Automotive Service Technician Period 1 exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

The key idea is that the secondary brake shoe takes on more braking force due to the servo-action mechanism. That action multiplies the force applied to the secondary shoe, so it experiences higher friction, more heat, and greater wear than the primary shoe. To handle that extra load, the secondary lining is made longer in its contact arc and thicker, providing more surface area to share wear and more material to absorb heat, which helps prevent fade and premature failure. The other reasons don’t fit the behavior of a servo-assisted system: heat buildup isn’t reduced by having thinner lining, and mounting position doesn’t change the force distribution—what matters is the greater force applied to the secondary.