Don't know exactly what you mean by notching the new nuts. After they have been tightened down and torqued to spec, you lock them to the axle by hammering the lip into the two notches that already exist on the axle. It's steel - they take a swift whack with a metal punch and a good size hammer.

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David.X5
2001 X5 4.4i Sport
SOLD! at 160k miles