The power behind the movement of the Plymouth drum brake wheel cylinder is the pressure being applied by the driver to the brake pedal. This process takes mechanical movement and converts it to hydraulic pressure which transforms it back to mechanical movement. This is the reason why the drum brake wheel cylinder can push out against the drum brakes shoes and create the friction necessary to stop your Plymouth. Today, the drum brake wheel cylinders can only be found on the rear wheel assemblies of Plymouth models. In the past, they can be found on all four wheels of a Plymouth. When the drum style of braking system is on a wheel assembly, the drum brake wheel cylinder is located in the center upper portion of the backing plate. It is mounted with two hold down bolts. There are two pistons on its interior that push outward against the forward and rear brake shoes. It is this action that creates the friction against the drum brakes that slows the vehicle down. The Plymouth drum brake wheel cylinders are made out of metal just like the brake calipers except for the seals holding in the hydraulic fluid around the pistons. It is these polymer braking components that crack and split over time and use causing hydraulic fluid to leak from the system. When this happens there will be a puddle of brake fluid on the pavement and in the drum of the wheel assembly where the leak occurs. The only solution to the failure of the drum brake wheel cylinder's seals is the replacement of the component. It is the same procedure as a typical brake job with the added step of removing the wheel cylinder before the new brake shoes are put into place.