Thank you very much for the answers.

There is a special nut for the crankshaft. I know that. But my question was if i could find a similar nut in a ordinary ironshop. But probably I can’t. It’s just that 10 € for a nut is kind of expensive.

I have a question about the Malossi MHR nut which includes with the malossi crankshaft. The one I have is torn and come loose when I drive. SO my question is if I must buy a new one from for example Mopshop, or if I can find it in a oridinary ironshop. Do somebody know?