Cast iron provides a durable material for shower drains and other plumbing fixtures. If you need to replace your old cast iron drain for a new one, removing the drain body from the shower floor as well as the drainpipe requires you to use specific tools. With the proper tools, removing the old drain and installing a replacement should take you no longer than an hour.
Remove the screws holding the shower's drain cover in place with a screwdriver. Insert a skinny screwdriver into the drain cover's opening to lift it out of the drain body.
Insert a drain key into the drain body, then turn the dial on the drain key to expand it. Stop turning the drain key's dial once the drain key fits firmly inside the drain body.
Clamp an adjustable wrench to the textured top of the drain key. Use the wrench to turn the drain key and the drain body counterclockwise, unthreading the drain body from the drainpipe below.
Move the drainpipe below the shower to the side slightly using your fingers, then pull out the rubber gasket. Insert a new rubber gasket into the space between the bottom of the shower pan and the drainpipe.
Spread silicone caulk around the underside of the new drain's lip. Thread the drain body into the drainpipe, expand the drain key into the drain body, and use an adjustable wrench to tighten the drain body in the drainpipe. Remove the drain body, position the drain cover and drive the screws through the cover to secure it in place.