You can leave them together but they will unscrew, just make sure they're totally empty and clean inside. The heat will cook the crap left in there and will be impossible to remove then. If you're getting the entire fork PC'd, I sure wouldn't bother separating them. If only the bottom, still OK to leave them together, just make sure the inside is clean as mentioned. I've seen them separated but only after a lot of effort, the locking goo they use on the threads is something to behold. A fellow at the plant told me they use that stuff " 'cuz we just as soon you didn't take them apart." That was good enough for me.
