I know this might sound like a stupid question but which way round do you fit grooved discs?

pics would help

 

Grooved goes on outside i would think mate,unless grooves are on both sides but i wouldnt know as never had a set,but you can see grooved disks through wheels so id say outside.

 

As supplied by Godspeed

 

Look at the above. Imagine those discs whirling round on the sides shown.
The one on the left moves clockwise, the other anti-clockwise.

Now imagine the groove is a jet of water, or sparks from a catherine wheel: what would they do? They would bend as the grooves do.

That's how I remember it.

 

Think there is two options actually. One way prolongs disc life , the other prolongs pad life.

 

Some manufacturers specify different ways,my front K sports go against the wheel direction and my rears from godspeed go with the wheel direction,both specified by the makers.

 

i thought if it went against wheel direction it would be better braking, thats why i asked, does it really matter which way round they go?

 

It depends on the vanes inside the disk:

 

As above. Groves can run either way. Its the central vanes that are inportant

 

oh ok now i get it cheers