@Kornsteven,
(pls see pics) the big 39mm nut I do as hard as I can on this flat piece without stripping the flange, holding the clutch pulley with an oil-filter spanner (belt type).
The assambly nut , 17mm, I fasten to 90nm with a torque. Both nuts get a few drops of blue Loctite 243 on it just in case.