Can and how do you replace the metal floor flange? The one I have has rusted through and one side of the toilet won't tighted.

Try a flange repair kit. Ace - Ace Tree: Plumbing: Toilets & Toilet Seats: Toliet Repair Parts: Toilet Repair Kits: Ace Toilet Flange Repair Kit (014703) (http://www.acehardware.com/sm-ace-toilet-flange-repair-kit-014703--pi-1272614.html)

Hey Guys!

Bob showed you the correct spanner flange to use in your situation.

If want to "step it up a notch"... could also use a new closet ring (see pic. #1) or could cut the old metal ring off with tin snips and use the CLAMSHELL (click on theclam2.pdf... the clamshell slides under/into plastic... like making a completely new flange)... sold at most PLUMBING supply stores.

But if only one side of flange defective... try the spanner flange Bob showed you... should do the trick.

Mark