Well ok, time for back to basics. Do not hammer on the flywheel nut, which probably damage the shaft threads. Use a flywheel knocker. It will remove it without damage. You can buy them, or make your own for less than a buck. Find two nuts, same thread as the flywheel nut, and a short bolt, the shorter the better. Screw one nut onto the bolt, then the other one on only a couple of threads. Run the first nut down to jam against the second one. You have just made a special tool.
To use, hand tighten the tool onto the shaft. Lift or pry the flywheel upward. Give the tool a rap or two with a hammer, and the flywheel will pop loose. Put the sledge away, and use a hammer 12 oz or 16 oz at the most. It is the shock that does the job, not the bash.
