Organizational issues: Filing

How do you file warranty and instruction books? Years ago, I bought an alphabetical expanding file, and it's served me well. But it is stuffed so full (even after cleaning it out) that it's tearing out at the bottom. Problem is some extra-large instruction books that came with power tools, pellet stove, etc. If I take them out and do something else with them, I've defeated the whole idea of having everything in one place. Do you have a "one place" idea that might work for me?

Also, my 2 drawer file cabinet, in which I keep all important papers, is letter size. But I own 3 properties with legal size closing documents. Any ideas? I wouldn't mind a portable file box for just those things, but don't recall seeing anything very portable that would accommodate legal size. It doesn't need to be very big, which is why I haven't bought a legal size file box.