Lester,
I am new at mower racing as you can probably tell. when you write ''easy to modify the steel hub'', from what l can see the steel hub is just the inner part of the billet flywheel, that sits over the end of the crank, with the o/d much smaller than the flywheel's o/d. Am l looking at a different type of steel hub to the one you are writing about?
neil.