bathtub
Is there a smaller size that's standard? I pulled out a broken bathtub drain insert because it was broken, and the standard 1-1/2 inch size does not fit. Is there another standard size that fits maybe older homes? The house was built in 2002, but it looks to be a pretty standard shower/tub insert.
The thing is the 1-1/2 inch tub stopper DOES fit through the hole in the tub but not in the actual pipe below (it's too big to thread in). Any ideas?
While caulk is fairly elastic, it handles better under compression than tension. By filling the tub all the way, you expand the gap quite a bit. Once the caulk is applied and the tub drained, the caulk compresses. During normal use, the caulk will likely never be in tension. As you'd have to add more weight than a tub full of water, before the caulk had to fill a gap larger than when it was applied.
Also, there's an old saying. "Happy wife, happy life" - Unknown
I have to comment that that tub structure is not really designed for a shower. You would have to install a shower curtain that draped into the tub on at least three sides to prevent water accumulation along the walls beyond the lip of the tub.
As a suggestion you could look into a shower kit designed to convert an old style free standing tub into a shower but personally I think it would really uglify your bath area.
Best Answer
You also find drain assemblies with 1-1/4" tailpieces, but they're almost exclusively used for sinks. They're used with a 1-1/2" to 1-1-/4" reducer since the PVC drain plumbing usually won't be smaller than 1-1/2".
The diameter of the actual threaded drain assembly isn't smaller in these cases. They fit the sink/tub the same way. Just the tailpiece is smaller.
Post photos of your situation for more specific advice.