Just took Centa out of a b128cu/in engined m3w - 10,000 miles - rollers shredded to pieces.
Nut on tight.
Pulled Centa housing off by hand.
Splines are perfect condition.
So although the splines might be a factor in the issue with the nut undoing - personally I think the splines are not as super critical as made out to be - the nut tightness is as important or more than likely more important.
I still think the rollers are the main culprit as Laurens explained earlier.
