Oversized Kohler Clearpass Tub Drain - What are my options?

[BikeNHV]

I'm about to do a tile job in my bathroom, and trying to finalize the decision about the tub - keep or replace. It's a kohler cast iron tub in refinishable condition. I would prefer to leave it in place due to the hassle of removal, and it just seems right in an older building.

The one sticking point is the tub drain. It's larger than standard size, see below. What I'm hoping to do is take it all out and replace it with a newer drain assembly, this will be easy since the walls will be open. But I don't know if there's enough "meat" on the tub to seat the smaller OD drain.
If the upgrade is not possible, I'll have to piece together the repair parts for a cosmetic repair, and also address why water pours into the basement when the water level reaches the overflow (bad gasket I'm assuming).

Good discussion about this drain/tub type here:
https://www.plbg.com/forum/read.php?1,335384

Which led me to this diagram, which I think is what I have now. Kohler's site says its all discontinued but I believe service parts are available:
https://www.guillens.com/kohler/Kohler SP4 (D)/svcparts/pdf/087926_8.pdf

What I'm hoping to install is a typical Gerber drain. The flange diameter looks to be 2 3/4:
https://s3.amazonaws.com/gerber-gh/579a4f24818af64912fbbb79/41-813.pdf

Because this is the only bathroom in that unit, I don't want to take the drain apart, possibly breaking something, then end up having to wait weeks for my supply house to get the repair parts (if they exist).

Any thoughts?

 

[Jadnashua]

Unless you actually remove the tub and then they can sandblast then refire a new porcelain coating on it, none of the things they can do in your home will last anywhere near as long as a new CI tub. That's not a cheap endeavor, and may cost nearly as much as a new tub (but I'm not sure on that!). There's evidence of damaged finish as seen by the rust spots.

If you're going to be spending a lot of money redoing the bathroom, I'd seriously consider replacing the tub.

 

[Sponsor]

 

[BikeNHV]

I got a quote from someone who's been doing refinishing for many decades, which I think is my best option. Lots of good feedback from other customers. I do understand that it isn't the perfect solution.

There are quite a few reasons that I'd like to keep the existing tub. It's an old 2-family house in a neighborhood mostly full of grad students and young professionals. I can't justify the cost of a new cast iron tub, yet it seems like a shame to stick a plastic tub in a house that retains much of its historic charm.
Also, the unique geometry of the existing tub preserves walking space in a narrow bathroom (1872 house, definitely shoehorned in after), while also being compatible with standard shower doors (not a "curved" tub). If I replaced it, I would have to step down to some odd small width and lose bathing space, or get a normal 30" tub which would put it annoyingly close to the toilet.
Refinishing over replacing also reduces downtime of the bathroom. Given the odd geometry, I'd definitely end up with a bunch of framing and drywall work if I tried to stick in a new tub.

 

[Marlinman]

Look for Watco 38390W. This will give you a 3" wide flange and 2.11" thread for the Kohler tub shoe. This has a push/pull stopper and a blank face plate. The kit will give you a bar at the top for the overflow plate to adapt to. You will need 2 each #10-24 screws to attach the bar to the overflow.

 

[BikeNHV]

I did see the Watco options, but if I was to go with something like that I think I'd just try to get the Kohler replacements so I could keep the trip lever functionality (it does work, just needs new gaskets).

But really I'd rather replace the entire drain assembly with a standard size Gerber unit linked in the first post. But I don't know if there is enough "meat" on the tub to seat the smaller 2 3/4" standard size drain.

 

[Marlinman]

The trim parts are still available. This is the Kohler link and go to the 2nd "Drains Interactive Diagram"

https://www.us.kohler.com/us/carmon...419717/419717.htm?skuId=360222&brandId=empty&