Today were going to review part number 8605001. This is the Demco Surge Brake Actuator for drum brakes. This is a bolt-on installation. As you can see on the side here they have two holes on each side to be mounted. Those holes center-to-center are 3 inches apart. Now this actuator is designed to fit on a 3-inch wide straight-tongue trailer, and basically the channel width right here as you… see more >