can you fit grooved discs the wrong way? i have grooved discs on mine but been complaining about them since i got them. my mate has a classic and his (although different discs) seem to spiral the other way?!

does it matter which way they curve?

even if i swapped them over would it not just be a mirror and they would still curve the ssame way??

i hope this all makes sense lol

 

The outer grooves doesn't matter if the vanes between the disc surfaces aren't directional, these do the cooling action of the vented discs.

Grooves simply deglaze the pads, most discs come witha left and right sticker on them.

 

no i mean the groove's that run on the face of the disc

 

As richie says, it doesn't matter about the outer grooves on the face, it's the inner vane direction that matters. If this is directional then they need to be fitted the right way for cooling, if not then you can swap them over.

Maybe your friend has better pads or calipers?