Adapting hydraulic brakes to 34 spindle

[Ken/Alabama]

I’m adapting 46-48 brakes to 34 spindles. Bought a kit that came with two spacers and two cast piston rings. Even though the piston ring fits nicely inside the backing plate and registers nice on the spindle I just don’t like that idea much so I modified the backing plates to fit the spindles. More work but I feel better. So the next issue is the small ring that fits over the spindle. Is this supposed to be a tight fit so it can’t rotate ? These are definitely not, I can spin it with my finger. And what exactly is the purpose of this ring, spacer. First time dealing with this .