I'm trying to remove a freewheel cassette. It's the Suntour two-notch kind that should open with a Park Tool FR-2. I've got the tool, but that notched ring vetoes my most muscular pleas for withdrawal.
Here's a pic of a FR-2 freewheel:
To get to my situation, picture the cog stack protruding about 1cm further out than the freewheel body; then imagine an 18-spline lockring on the surface of the outer edge of the freewheel body. What the heck is that? It resembles a BB lockring. Diameter ~31 mm. It can't be holding the cogs together because it's deep inside and doesn't even ratchet with the cog assembly. Whatever it is, Park Tool doesn't make a tool for it. Do I need to open that lockring in order to get the notched ring to unscrew, or is it irrelevant for my task?