i routinely clean and lube my caliper slides when i change my brake pads (i'm on my 3rd set of pads as i do lots of stop 'n' go traffic). i noticed that the little rubber piece that fits over one of the sliders was torn and corroded. not the accordion boot....the rubber piece on the actual slide.

i reinstalled the slide without it until i can get to the dealership, but my question is why does only 1 slide per caliper have this little 'booty' on it?

without it on there, it seems the pistons are dragging a bit on that side as i'm getting a 'brake smell' from that wheel.

any ideas on that?