If when handling the rubber your hand gets stained black, replace it.

If it looks like mine (soft, sagging, etc.), then replace it. Some stores sell the rubber separately.

OK so the rubber comes out of the metal drain part but the metal part can be re-used...I have never replaced a sink before, I am sure I can figure it out be taking it step by step but I wanted to try and get all the parts I might need before I start - so I can avoid multiple trips out to the hardware store in the middle of the job!

The sink is a single bowl with disposal, and the dishwasher drain/air gap is also involved. I am hoping I can just detached the whole assembly from the old sink and then re-attach to the new sink.

The sink is old but the disposal is newer.

Are there any other parts I am likely to need to replace?

All the online guides I can find refer either to replacing a plain sink with no disposal or to replacing a disposal but not the sink. If anyone has links to a guide on replacing a sink but keeping the disposal (and preferably involving a dishwasher hookup too) I would much appreciate it!

Well, if you're keeping the old one, I would just go to HD or Lowes and buy the kit. This is usually a new shiny mounting flange, rubber parts and perhaps the mounting 'clamp' stuff.

Cast iron is heavy. You'll need a friend to help you lift it out.

You're pretty much correct about the order of things. Remove the old GD first, disconnecting the drain and the DW/airgap hose and electrical. Set the GD aside. Then remove the old sink.

Assuming your old faucet is not part of the sink, you put the new sink back in. If the faucet is involved, you would usually attach the new faucet (or the old one) onto the new sink before putting it into the cabinet.

put the new flange in the sink with plumber's putty.

OK I bought a p-trap and drain kit just in case, and a gasket/baffle pack to replace the rubber parts which are probably degraded somewhat. Hopefully I can simply re-use the entire thing including the metal flange and only replace the gaskets.

I'll tackle the job tomorrow - not really looking forward to it as it is a tiled in sink and I'll be chiseling out the tile before I can get that 30 year old thing out.

If I get stumped I'll be back here tomorrow with my questions!

Well, the only thing I would say about the flange is that a new one will look better and they don't cost that much.

I have the old sink out, the disposal detached easily from the collar/flange. The hard part was chiseling the tiled-in sink out, tok me 2 hours with breaks and a lot of sweat. But it's out faucet and all! The disposal and all plumbing seems to be in good shape, I put a box under the disposal to avoid putting its weight on the pipe and just left all that stuff hooked up.

So the old flange collar thing is worn and scratched and I can't figure out how to remove it anyway. I loosened the screws on the bottom and the triangular part turns but doesn't unscrew.

I know I can buy a new flange/collar but this does not appear to come with the lock mount collar that remains attached to mine (see link below), is that another part I need to buy as an assembly?

Here is a link that might be useful: Lock Mount

There is a spring retainer ring you need to remove. Push up the loose triangle, , then remove the ring with a screwdriver (catch it with the screwdriver where there's a break in it).

Also, you need to disconnect the disposer and lay it down. Later, hang it, and then connect the plumbing afterward. Right now it's just in the way.

When when you reinstall the flange to the new sink, be sure to use plumber's putty and get that triangle tight. (When you reinstall the spring retainer ring, have another person above to push down on the flange as you install the ring. (Newbees have a hard time with this.)

Good luck.

homebound , thanks so much - I will try to remove the quick-release collar fro the old sink. I am probably going to replace it anyway since a new one is only $15 but I thought I might need the triangular collar.

When you say push down on the flange do you mean from inside the sink, or when I have it upside down? And when you say get that triangle tight, tight up against the sink? And one more question if it's not to annoying - have another person push down on the flange as I install the ring onto the disposal, or just onto the sink? Is that to ensure it doesn't pop up out of place?

Sorry for the confusion. Push flange from inside the sink. You need an extra pair of hands to hold it in place while the other person snaps the ring back in place. Otherwise, as you try to put it on you might push the whole thing upward before you get the ring on.

Tightening pushes the triangle against the sink bottom as you turn the thing with the three screws (also triangular, maybe?). The screws push against the triangle. (the snap ring keeps both rings from falling off). Don't forget the cardboard (?) ring that goes on before the other parts - that should be against the sink bottom when it's all tight.

This post was edited by homebound on Fri, Feb 15, 13 at 20:42

Here's a video to look at.

Here is a link that might be useful: Disposer video

That makes sense, thanks! I just wanted to be sure I wasn't pushing the wrong way. Off to Lowes to get a new flange. Thanks for all your help and support!

After this, the bathroom sinks will be easy when I get around to them :)

Just came back to say thanks for the help! I got the new sink installed and the disposal hooked back up. I ended up replacing the flange and the collar because the whole assembly Insinkerator brand was $15 vs $25 for a flange alone from Kohler etc. Getting the ring back on was tricky, in fact I ended up pulling the sink back out and doing it upside down rather than trying to do it under the cabinet. It was easy that way.

No problem. Glad it worked out. Kudos for your efforts.

Before:

{{!gwi}}

During:
{{!gwi}}

Almost-after (concrete countertop not finished/sealed yet, backsplash obviously... but new sink and faucet look nice!)

{{!gwi}}

Your new sink looks to be much smaller than the old one. The small size may be a problem if that's the only sink in the kitchen.