Basic Repair: Swap the Drain Piece for Sink Swap?

I am swapping out a rusted sink for a new sink, but I need to take the drain piece off the existing and transfer to the new. The bottom of the drain piece (below the sink) has a nut, plastic washer, and rubber washer. The top of the drain piece (brass inset piece to make the drain hole look finished and aesthetic) seems to simply rest in place - totally fastened from the bottom (per hardware mentioned).

After unscrewing the nut and sliding the plastic washer out of the way, do I use the shank of a screwdriver to nudge the (tight-fitting) rubber washer down the drain pipe? And, is something more is holding this whole assembly together? Do I need a strap wrench to unscrew the drain assembly? Is it really two halves mated with screw threads? I do not see anything obvious that would release, unscrew, etc.

Also, once I disturb the (tight-fitting) rubber washer, is it reusable or a gonner? if a gonner, is it sold separately? (Someone said to me the whole drain assembly is sold with the faucet. Is that correct?)

Those willing to share their experience here, greatly appreciated.

I replaced the drain piece on my sink. It was just a few bucks, and sold separately. Mine was steel, not brass, so yours might cost more.

You need plumber’s putty, another couple bucks, to make a water-tight seal.

If your brass piece still looks nice, and is in good shape, you could reuse it. I was not able to reuse my steel one, because I damaged it removing the nut below the sink. There was so much corrosion, unscrewing it was impossible, and the threads were damaged while prying/cutting it off.

I would not try to reuse the rubber washer, just because they’re so cheap, why use an old one.

So, bottom line, don’t plan on reusing any of it, maybe you’ll get lucky with the brass part, and it’s not the end of the world if you don’t.

ETA for FYI: I didn’t change the sink. The “plastic washer” was paperboard in my case, and was leaking. I was just going to replace the washers and nut, but the corrosion made it a bigger job. Still no big deal.

ETA2: The hardest part of the job was getting the nut off the drain piece. If you’re replacing the sink anyway, unless your really attached to the existing drain piece for sentimental reasons, the extra ten dollars will be more than worth skipping the aggravation of disassembling the drain piece, IMHO.

One other thing, do you have a wrench large enough to use to tighten the drain plug nut? I didn’t, and had to make do with a clamp. It was a pain.

Thanks the pointers. The drain plug nut (under the sink) wasn’t hard to loosen with channel locks and minimal effort. I found a video online that shows how to put in the drain assembly, and how the flange piece (on the top side of the sink) screws into the stem (below the sink), but there is little to grip. For me, getting the flange off is next to impossible. I could be fighting some rust or corrosion in the threads, too. The exsiting is all brass. $100 bucks at Home Depot (online)! Crazy!

If anyone has tips to loosen the flange, feel free to share.

Well, the saga ends here: I found a new drain assembly with brass flange with the rest all chrome for $25. The $100 brass one mentioned earlier was all brass. So, $25 will save me a lot of headache. Thanks again, all!