Direction of grooves on discs

[markCSC]

Was at a local PH hoon yesterday and the conversation got around to grooved discs (sad I know). Mine have curved grooves and point backwards (arrows were drawn on the discs went bought).

like this (car pointing left)




Another guy had straight grooves and these pointed forwards.
like this (car pointing left)



So after a bit of Googling see seems to be the case (curved go backwards and straight go forward). However the new Merc C63 Black has straight grooves going backwards!!

(car pointing left)



Does anybody know why grooves go in different directions?

Thanks

Mark

[edited to pictures so cars are all pointing the same way]

Edited by markCSC on Monday 26th September 15:04

[kambites]

Those grooves all go in the same direction, assuming they're from the same side of the cars.

[rhinochopig]

The Merc has the same direction as yours

[Stu R]

The direction of the vanes in the centre are far more important than the grooves on the surface. Quite often the case where folks fit them the wrong way round.

[h0b0]

walk around to the other side of your car and see which way the grooves point

[TheEnd]

Going backwards seems to be the most preferred style, but it might be mainly for looks as I have seen grooved brake kits which aren't sided, so left goes forward, right goes back.

If a brake company is happy doing that, then there can't be much of a difference apart from aesthetics.

I have heard people say they are supposed to go in a certain direction to help clear water or something...

[markCSC]

kambites said:

Those grooves all go in the same direction, assuming they're from the same side of the cars.

The cars are pointing in different directions. I've labeled the pics now

[kambites]

markCSC said:

kambites said:

Those grooves all go in the same direction, assuming they're from the same side of the cars.

The cars are pointing in different directions. I've labeled the pics now

But the first and last pictures are still the same.

What does the other side of your car look like. Are the discs the same, or symmetrical?

[KevF]

Mark,

Ahh now I see what you mean thanks for sorting the images

Kev

Edited by KevF on Monday 26th September 15:28

[markCSC]

First pic curved grooves going backwards
Second pic straight grooves going fowards
Third pic straight grooves going backwards

The question is is there a technical reason for the dirction based on the shape of the grooves

[kambites]

I suspect (although this is only a guess) that each disc type only has groves going one way, so they'll be different on opposite sides of the car?

[AllNines]

Just had new discs on my car, and the grooves all point backwards. The vanes, however, differ from side to side. It appeared odd to my garage, but the discs they removed were exactly the same.

[markCSC]

kambites said:

I suspect (although this is only a guess) that each disc type only has groves going one way, so they'll be different on opposite sides of the car?

Mine go backwards on both sides.

[kambites]

Fair enough, I thought the direction of the veins was important, and the grooves didn't matter.

[Corsair7]

Stu R said:

The direction of the vanes in the centre are far more important than the grooves on the surface. Quite often the case where folks fit them the wrong way round.

This.

The direction the 'vented' grooves between the two disks matters, not the grooves etched on the disk.

[Arun_D]

Unless you buy a Lotus, where the discs often aren't handed, so the centre vents point in different directions from left to right!

[irf]

i've been told that when the grooves are facing the way of the second pic that this is more aggressive for performance, increased wear and slightly more noise. how true this is, i don't know.

[AllNines]

Arun_D said:

Unless you buy a Lotus, where the discs often aren't handed, so the centre vents point in different directions from left to right!

As I've just found out (see a few posts above).