The hydraulic pressure provided by the Chrysler Drum Brake Wheel Cylinder against the shoes is what creates the friction so the vehicle can be brought to a standstill. The drum brake wheel cylinder is the component in your rear braking system of your Chrysler that coverts the hydraulic pressure to mechanical motion so force can be applied to the drums.
There is a drum brake wheel cylinder on each rear wheel brake assembly on all rear wheel driven Chryslers. Each one is mounted to the top center section of the backing plate of this assembly. The top end of the brake shoes is fitted into the openings and is how the hydraulic pressure is transferred to them. Inside of the Chrysler drum brake wheel cylinders are two pistons sitting opposing each other. These pistons are forced out in opposite directions by the force of the hydraulic fluid entering the cylinder.
To hold then hydraulic fluid in place in the drum brake wheel cylinders is a set of polymer seals that cover the ends of the opposing pistons. It is these polymer seals that dry out in time and is the source of any hydraulic fluid leak in the drum braking system. Once there is a rupture here, each time the brake pedal is pushed, a portion of brake fluid will leak out and when released, air will replace the lost hydraulic fluid in the rear braking system on your Chrysler. This air will result in the brake pedal feeling soft and squishy when pressure is being applied.
The replacement of the drum brake wheel cylinder is the same process are replacing the shoes only the cylinder will have to be included in this repair procedure. Before removing the mounting bolts, loosen the brake line so it does not become damaged in the repair procedure.