tub drain replacement

[eVwWt3Y3daHm47mT5XmU6w47]

I'm replacing the tub drain part as shown in photo #1. The old part was broken and I had to destroy it for removal so I can't use it as a decent reference for a new part. The problem I'm having is that the mating female threaded part below the tub is smaller or has a different thread pitch than any of the drain parts I have on hand or have found in stores. Based on the attached photo #2, it looks to me like the original plumber installed a smaller diameter ABS fitting into the pipe below - a bushing, an adapter - what's the proper name for that part? I don't know if that part is threaded in or glued in. I'm wondering if that part can be removed with some careful dremel or chisel work, and that would then reveal either larger diameter threads or an ABS inner surface I could clean up for glueing in a larger diameter ABS bushing/adapter that is the correct size for my new strainer part.

 

[Geofd]

Do you have access to underneath and and behind????? Can you change the whole waste and over flow,usually those sizes are pretty common/standard

 

[eVwWt3Y3daHm47mT5XmU6w47]

Unfortunately, no access under/behind, so no, can't easily change the whole assembly or would gladly do so. Yes, I thought the sizing should be standard but none of the standard parts I've tried have fit. I've tried two standard Moen parts that I found at local stores and they seem to be the right diameter but they don't thread into the female part so I believe the thread pitch is different. A Moen M8649 is the latest part I've tried.

 

[GReynolds929]

Its probably a fine thread shoe, we use AB&A 1658CP for most replacements and never had a problem. I would try one of those.

https://ipsplumbingproducts.com/bra...-conversion-finish-kits-push-en-lift-stopper/