nut on flywheel removal

get a flywheel holder and use an impact wrench to drive the nut off. Then you have to use a flywheel puller to get the flywheel off
 
If in desperation one can use a hexagonal socket coupled with a breaker bar.

Get a buddie to hold the flywheel whilst you support the breaker bar, and smack it with a lump of 2x4 hardwood.

Had to use this system when I lent my holder to a guy who wanted it more than I did. Needless to say, he don't get to borrow any more tools.
 
You can make one, its pretty easy if you have some sturdy metal/steal, a drill and 3/8 in drill bit, and 3 3/8 in bolt with nuts. Google " home flywheel holder " and it'll bring you to a thread on here with pictures. You should check it out ! I made one and it worked pretty good, I think I spent $2 or $3 cause I didn't have the nuts/bolts.
 
You can wrap a ratchet strap around the flywheel in the opposite direction you will be wrenching, then hook the strap to the frame. When you start to wrench on it the strap will tighten on itself and hold the flywheel for you. Don't need the ratcheting part just the strap with the hook.
 
You can wrap a ratchet strap around the flywheel in the opposite direction you will be wrenching, then hook the strap to the frame. When you start to wrench on it the strap will tighten on itself and hold the flywheel for you. Don't need the ratcheting part just the strap with the hook.
that worked and saved me the money buying a flywheel holder