s4one

Slit in the rotor?

s4one

daberlin

Bunch of holes as well.

s4one

Lol I've never noticed this. What's the purpose of it?

FrenchToast

While I've never seen them contoured to the rotor like that, typically that is done to balance the rotor. In other words, it's a little heavy on that side, they grind down a bit to balance it out. Usually they grind it flat though, don't contour it.

The holes are usually for water escape. Their original use (decades ago) as ventilation has been proven to be negligible.

Sidvicious7

s4one

Interesting, never seen it.

Guards_Red_991

This is how my brain works... "Hmmm that looks odd and never seen it before, maybe I should get girodiscs and be done with it... Honey have you seen my laptop?" Any excuse...