Changing the drain fitting on a bathtub may become necessary at one time or another. The old drain may rust out, discolor or leak with time and use. The process for replacing a tub drain described here is for a garden tub in a mobile home. In mobile home plumbing, there are often differences in bathtub drains, because these tubs do not always have an overflow tube. In this type, the tub drain may be just a seal and nut that you tighten onto the tub itself.
In a standard site-built home, by comparison, the drain assembly is usually a threaded insert onto which a mounting nut is screwed from below.
Removing the old tub drain is the first step in changing a tub drain. You will have to look under the tub to determine how to do this. In some tubs, the drain fitting is removed from the top of the tub, while in others there is a retaining nut that will have to be removed from underneath. The directions that follow are for the type that is unscrewed from the top.
If there are crosshairs in the tub drain, then you can use tub drain wrench (sometimes called a Dumbell wrench) to unscrew the drain fitting counterclockwise. Since most tub drains have been in the tub for a long time, the chance of getting the drain out in one piece can be slim. If the crosshairs break off, you will have to get the drain out using another means.
If the crosshairs on the drain break cut the fitting with a mini hacksaw or hacksaw blade. Cut down the threads and through the rim, but not deep enough to go into the tub itself. Then, make a second cut about a 1/2″ away from the first cut. With a flat screwdriver, you can lever the cut segment out. Once the cut section is removed, use the flat screwdriver to pry up one of the edges of the drain fitting and unscrew it in the direction you would normally. The fitting should come out with a little work.
Next, prepare the new drain fitting and the drain pipes for installation. Beneath the tub, you will find a trap secured by a nut. Unscrew the trap and move the drain pipes out of the way to make room for the installation of the new tub drain.