Drum System Backing Plate
Steel plate backing plates are used to assemble wheel cylinders, brake shoes, and other related hardware onto a drum brake unit. Disc brakes have backing plates as well. If either backing plate gets bent of damaged during a brake job, a squeaking sound will be noticed as the vehicle pulls away. Just straighten the plate to repair the squeal. Rear drum brakes have pads that must be level with each other. Care should be taken to ensure that the brake shoes are running parallel to the drum surface. These plates are also vital in keeping elements such as water, dirt and debris away from system components.
Wheel cylinders, springs, and other hardware are fastened to the backing plate in a drum brake system. The shoe pads on a drum brake systems backing plate can become scuffed and grooved as the shoes move back and forth on its surface. These pads can be sanded or filed smooth to restore surface integrity. When finished, apply a specially formulated high temperature grease to these pads to protect and reduce brake squeal.
Brake shoes are held in position by springs and clips. These springs create pressure, resulting in grooves and scratches in the plate. Use high temperature brake lubricant that can withstand the high temperatures generated by drum braking systems to protect these pads. Avoid petroleum based greases that can swell rubber parts and chassis greases that burn off and evaporate.
There are actually two types of lubricants used in automotive braking systems. Silicon based lubricants work well on rubber and plastic parts and there are lubricants used for hardware components like the shoe to backing plate area. These are hardware lubes made of synthetic, graphite, or silicon dry film lubricants formulated for high temperature brake systems.