Grooved discs, which way round??

[mcbutler]

So guys,

Got a pair of grooves discs, I need to know which side they go on as the grooves run in a different direction depending which side I put them on!
So, which side does the disc pictured go on?
No guessing please If you know, you know.

 

[GuidoK]

Don't look at the grooves but look at the vanes inside the vented disc.
Those have to be correct (scooping in air when going forward)
Way way more important.

The grooves are there to relieve possible gasses coming out of the brake pad. That's very minimal.

 

[flybobbie]

They cool via centripetal force throwing air out from the hub, not by scooping up air. They are a sort of impeller like inside hoovers or turbo charger.
https://www.youtube.com/watch?v=krLOy90KrvY

 

[Gazza51]

I’ve just fitted discs to a classic Mustang and the instructions state the grooves should go from centre to outside if rotated clockwise, so your pic would be drivers side.

 

[Leek78]

see, https://www.mtecbrakes.com/brake_disc_fitting_bedding_in

 

[mcbutler]

Thanks guys, so much info on this its all confusing.
The direction of the inside cooling vanes is apparently of primary importance, if they are 'scooped' they lean to the rear. If the internal vanes are simply inside to outside then direction of groves is irrelevant, like mine and BMW OEM
Some, for example 'MTEC' say grooves leaning to rear others 'Brembo' say grooves leaning forward.
I have gone with grooves leaning forward, any snags like squeaking and I will swap them over.

Thanks for all the advice

 

[flybobbie]

https://www.bremboparts.com/europe/en/products/brembo-max/the-perfect-response#:~:text=Brembo%20Max%20features%20exclusive%20grooves,)%2C%20preventing%20pad%20surface%20glazing.&text=One%20of%20the%20Brembo%20Max,the%20brake%20disc%20wear%20conditions.

For those that are totally confused.