I'm replacing some old Shimano cantilever brakes with Tektro CR-720s. The old ones had a plastic spring housing (that is apparently hard to find now); the new ones do not. Am I just supposed to install the spring without anything around it? Is this OK? It seems odd in that the springs are around a painted boss (wouldn't it rub?) and there's a bit of room fore/aft of the spring coils when installed.
I haven't inspected any cantilever brakes without any housing in the wild, so I don't know what they're supposed to look like.