Clear enough space under the sink for the garbage disposal. Measure the height and width of the disposal and all connections. The disposal system should not touch any other objects under the sink.
Remove the drain from the sink. Unscrew the nuts of the P-trap--the curved pipe under the sink, the top of the extension pipe and the bottom of the flange. Push the flange upward and out of the sink. Clean the area with a dry rag.
Take apart the mounting assembly for the garbage disposal. Lower the mounting ring by putting a screwdriver in one of the mounting lugs and pressing the ring down. Use your hand to turn the mounting assembly counterclockwise while you hold down the mounting ring. Remove the mounting screws from the bottom of the mounting assembly. Pry off the flange of the garbage disposal with a screwdriver.
Install the garbage disposal's flange in the drain hole of the sink. Apply a ring of plumber's putty around the perimeter of the drain hole. Sit the flange on top of the ring and press it downward into the putty until it rests on the surface of the sink. Scrape away the putty overflow with a putty knife.
Connect the mounting assembly of the garbage disposal to the flange in the sink. Place the backup-ring fiber gasket and the mounting ring over the flange from the underside of the sink. Secure them in place by sliding the snap ring in place. It will click when pressed upward into the mounting ring. Align the mounting screw holes of all the rings. Install mounting bolts into the holes and tighten them into place by turning them clockwise with an adjustable wrench.
Connect the garbage disposer to an electrical source. Remove the screws from the electrical plate on the side of the disposer. Pull the cover and the black and white wires from the disposal. Run the black and white electrical wires from your electrical source through the access door on the bottom of the disposer. Strip back a 1/2 inch of insulation from the disposer's wires. Connect the black and white wires from your electrical source to the black and white wires from the disposal. Twist the exposed wires together. Wrap the connection in electrical tape, and slide a wire cap over the electrical tape. Run the ground wire (bare copper) from your home to the ground wire (bare copper) of the disposal.
Attach the disposer to the mounting assembly in the sink. Slide a rubber flange and then a metal flange over the discharge tube of the disposer. Line up the holes of the two flanges. Install bolts in the holes on the rings and tighten them by turning them clockwise. Turn the disposer until its discharge tube is lined up with the P-trap of the sink's drain pipe. Install a beveled washer followed by the P-trap nut to the bottom of the P-trap. Secure them in place by turning the nut clockwise with an adjustable wrench.
Label the disposer. Apply the supplied specifications label to a place on the side of the disposer where it can be seen easily. This label contains information for future repairs and service.