Chapter 12 Disc Brake System Components and Operation 187 Copyright by Goodheart-Willcox Co., Inc. caliper mounting and lining. Some shoes have alignment dowels stamped into the metal. Anti-rattle springs or clips that reduce brake squeal may be riveted or welded to the shoe. Some clips are snapped on the shoe, and must be installed or transferred from the old shoes when new shoes are installed. Lining-to-Shoe Attachment Th e lining is attached to the shoe in one of two ways. One method is riveting. Brass rivets are used to attach the lining to the shoe. Th e lining and shoe are made with a number of matching holes, with the rivets installed through the holes. Th e rivets are then secured tightly using the proper riveting tools. Brass rivets are used since they will not cause as much damage if the lining wears down until they contact the rotor. A riveted shoe can have anywhere from two to eight rivets. Th e second method of lining attachment is called bond- ing. Bonding is a process that glues the lining to the shoe. A special high-temperature cement or epoxy resin is placed between the lining and shoe. Th en the lining and shoe are pressed together until the cement is thoroughly dried or cured. Some cements require heat to properly dry and hold. Noise Reduction Devices Common brake noises are squeaks and squeals from brake shoe and rotor contact, and clicks and knocks from loose pad to caliper contact. Various clips, springs, and other devices are attached to the brake pad shoe to reduce noise. When the pad is installed on the vehicle, these form a ten- sion fi t with the pad and other parts of the brake assem- bly. Th e springs and clips absorb some of the vibrations and noise from the pad as it rubs against the rotor. Other designs use a piece of fl exible heat resistant material, sometimes called an insulator, installed on the back of the pad. Th is material also absorbs noise and vibra- tion. When used, they are installed on the outboard pad, against the caliper housing. Some designs have insulators on both pads, while others use a fl at metal plate called an anti-rattle clip, plate, or shim. Figure 12-22 shows diff erent noise reducing clips, springs, and shims. Anti-rattle springs Anti-rattle springs Anti-rattle springs Caliper carrier Anti-squeal shim (outboard) Anti-squeal shim (inboard) Anti-squeal shim (inner outboard) Anti-squeal shim (inner inboard) Brake pads A B C Anti-squeal springs Anti-squeal springs Chevrolet Figure 12-22. An assortment of noise-reducing items. A—Shims and springs. B—Four anti-rattle springs. C—Anti-squeal springs in their mounting position.