bathroom-fixturesshowertools
Underneath the shower handle I've found this interesting design where there's a cover or shroud encapsulating the cartridge. The threading on it is interesting: the threading isn't required for the handle and there are two flat areas near the end. I'm guessing there's a special tool I should use to get access to the cartridge. (No, I don't think I'm referring to a cartridge puller.)
How would I find this tool? Or can anybody identify the manufacturer?
The next step secret to getting more of this faucet apart are the two slots cut across the cupped part. See the arrows in the following picture.
It looks to me as that the cupped part is threaded down inside the larger diameter part that sticks up from the hole in the sink. There is probably a special tool used to engage these slots to thread the part out. It may be possible to lay a piece of metal bar stock across these slots as a tool. If you do that make sure that it has nice square corners.
That appears to be intended to pry out with a screwdriver or similar flat tool at the indents a little past 6 o'clock and a little past 12 o'clock as pictured.
Best Answer
Does not appear to be any "special" tool requirement per these pictures.
Put a strap wrench on the outermost silver bit and unscrew, or (judging the beat-up look it already has) just scar it up some more with slip joint pliers like the last guy did, at a guess. If the central part turns when you do that, put a wrench on the flats to prevent it from turning as you unscrew the silver part. If the silver bits are more conjoined than it appears, you might need to take the screw(s) in the wall out too.