I had a stem that was super rusted in a fork that I really wanted to save. I cut the stem off above the fork nut so I could get it out of the frame. I had heard that heating rusted parts red hot and dousing them with cold water will cause them to shrink enough to break the rust bond. I don't have a big acetylene torch, but I do have one of those little single burner camp stoves that screws on top of a little propane bottle like for a Bernzomatic torch. So, that's what I did. Roasted that fork and stem like a hot dog and plunged it into a bucket of water a couple times, clamped it in the vise, snapped on the vise grips and voila - out it came!!
