I think I read every topic on this sight about these,anyways I have two questions, I have a 2001 Ranger trail with the big sight glass COOL.
Question #1. As I drain them the sight glass seems to suck in as the oil drains,I`ve read that they are spring loaded? When you refill the hub is it supposed to come back out or does it stay in?
Question #2. How much oil? I`ve read,fill them til the sight glass is completely full,this still allows room for more oil back at the fill plug.
I have also read fill them to the bottom threads on the fill plug,because you don`t want any air in them,which is it?

Thanks