Brake disc groove?

[MLB]

Just fitting my new discs I noticed a grooved bit on the side of both discs, one slightly longer than the other.

Does it mean anything? Not seen this on Brembo discs I've used before.

 

[MarkCup]

Isn't that where they've machined material away to balance it?

Or is it techincally the 'wear' indicator?

Or both?

Or none?

 

[JackJack]

I bought some discs from godspeed before and they had the same, guess it is a balancing thing.

 

[MLB]

Yep I used the wrong terms in Google.. It is to reduce brake disc imbalance.

Mill Balancing: Why Is There a Notch in My Brake Rotor? | PowerStop

Is there a machined notch in your brake rotor? This is for mill balancing, which can reduce vibration and improve the life of your brake rotor.

www.powerstop.com

 

[PhillipM]

It's both balance, and to break up squeal harmonics (which is why you sometimes see them in 2-3 spots the same depth)

 

[MLB]

Cool, not seen that before.