Depends what mood I'm in and whether they are gas charged dampers as to the method I use. A grinder is good, just a simple verticle cut up the middle of the shaft/nut (if the nuts are stuck on then the damper is probably had it anyway), but its no good for the bottom of the front dampers as its surrounded by bracket and axle. I have split the front nut using a big hammer (cut the hand of a sledge hammer short so it can be swung one handed) and chisel, but because of the bush the nut bounces back and is a right PITA to split that way.
Going back to the damper not being gas charged bit, the next time I have a lower nut stuck on a condemded front damper it will most likely get cut of with the oxy-acetaline, its very satisfying when your problems just melt away in to a blob of liquid metal.
Depending just how stuck the nut is stilsons work well (but fitting them between the coils on the front can be interesting) at stopping the damper turning and if the nut is only slightly stuck then a rubber strap wrench doesn't damage the damper. I dislike the 8mm flats on the ends of dmaper threads, there better than nothing, but only just.
