A wheel cylinder is just a cast iron piece with a precision-bored hole, with aluminum pistons and rubber seals to receive the pressurized fluid and transmit the force to the brake shoes. Start by removing the shoes, and pulling the rubber dust boots off. Don't worry about saving them, the rebuild kit will have new ones. Some dust boots are a press fit into the cylinder, others overlap the outside diameter. There should be NO fluid inside the dust boot, it's only there to protect the piston. Push the pistons and seals out, clean up the cylinder bore with alcohol and a clean rag, and inspect the bore for rust pits. Sometimes, the cylinder will be too badly pitted to recondition. There is a brake cylinder hone available to polish the inside of the cylinder, but if you don't have one, use a piece of wet-or-dry sandpaper and some brake fluid for a lubricant, and polish the inside of the cylinder. Use a rotating motion, so you don't create lengthwise scratches in the cylinder bore. Wash thoroughly with alcohol to remove all the polishing grit. Clean up any rust or corrosion on the pistons with the same fluid-lubricated sandpaper, and wash thoroughly. Reassemble with the new seals (cups) and the old pistons, with the sealing lips of the cups pointing inward. Lubricate the cups with fresh brake fluid during the reassembly. Most wheel cylinders have a spring with a cup expander on both ends to help the cup keep a tight seal against the cylinder wall. Snap the dust boots on, install the pushrods that mate with the brake shoes, and reinstall the shoes. Be sure to get all the springs and other parts back in the right place. Some guys like to leave one side assembled while working on the other, for a reference, but remember each brake will be a mirror image of the other side!
Simpler, and quicker method: Buy new wheel cylinders, and bolt 'em on! Bleed the brakes, and you're done!
Jerry
