Grooved Discs Rotation Pattern

[james.l]

Got some new EBC grooved discs today from CRN, just wondering, is there a specific way to mount these, i.e whcih way the groove rotates, my cars grooves currently go \ that way going forward, i thought they where meant to go / that way going forward.

Any ideas?

 

[JamJay]

I recently put new EBC discs on mine and they were labelled 'left' & 'right' on the boxes. This is how they instructed to mount mine:

So the grooves are going / this way.

 

[james.l]

well that means that both the front & the back of mine are on the wrong way! grrr

 

[D_O_U_G_I_E]

On a slightly different note....what are the EBC grooved discs like? Worth purchasing? Any issues?

l need to replace mine and have been looking at these over the past couple of days, but some reassurance from other LCR drivers is always good before parting with cash!

 

[ibizacupra]

On normal vented road disks usually groove leans back against direction of rotation

eg: on my 8 groove badger disks below would be OS disks

NOT always the case on performance rotors however, where cooling vane direction sets the orientation

 

[JamJay]

I'm not sure if there are negative effects to how you have them fitted, maybe just more disc noise.

This comes from the EBC site:

The way I understood it is that that inside of the grooved (nearest hub) should touch the brake pads first so that excess dust is pulled through the groove and off of the outer edge of the disc as it rotates.

Edit: This is for Turbo Groove discs by the way so Ultimax discs (assuming that's what you have) may be different.

 

[Dyscontinued]

When I got my grooved discs I thought they went with the groove angled forwards, but when I came to fit them one of the 5 wheel nuts wouldn't fit as the holes didn't align.

They were labelled Left and Right but I though I knew better lol.

 

[james.l]

dammit, more work for me at the weekend swapping all four corners round then. grrr

 

[JamJay]

Not necessarily james, see Bill's post, his are designed to run the opposite way around to mine. He uses EBC plain discs and grooves them himself, you may have the same thing but from CRN.

 

[james.l]

i have ordered EBC plain that have been grooved by CRN, couldn't afford the ultimax discs and have already got the CRn on the car, isn't bill saying that same as you though that the groove should go in teh direction of travel?

 

[DPJ]

When we bought a group buy of Galfer grooved disks, there was the option to fit them 'agressively' ie with the grooves sloping towards the direction of rotation.

As Bill says, you should look at the ventilated slots in the middle of the disk - these should slope forward to 'scoop' air into them.

 

[Slimy]

There's no consistent way round, it is how the disc is manufactured as a unit that determines whether they're backwards or not. Both the grooves and the vents work together to deliver the best braking and cooling ability that the disc can deliver. I did think they were meant to 'sweep' inside to outside, but that theory was disposed of when I went to see the BTCC a few years ago and saw their discs apparently on backwards!!

EBC brakes (from what I remember) sweep from inside to outside, and the vents are also designed to work the same way round. But I remember an old manufacturer who made black discs and they were meant to mount 'backwards'.

Dyscontinued, your bolt alignment can't have been caused by the orientation of the disc. Every wheel has equal spacing between their bolts, whether they're left or right. If your discs had a 4 bolt and a 5 bolt pattern on them (as alot of discs do, like the left one of ibizacupra's picture), you might find rotating them a hole would have given you your fifth hole.

James.l, check with the disc manufacturers before you go to the effort of swapping them?

 

[Slimy]

As Bill says, you should look at the ventilated slots in the middle of the disk - these should slope forward to 'scoop' air into them.

Not necessarily always the case, the disc could be designed to use rotational force to suck in air from the centre and disperse it outwards.

 

[Dyscontinued]

Dyscontinued, your bolt alignment can't have been caused by the orientation of the disc. Every wheel has equal spacing between their bolts, whether they're left or right. If your discs had a 4 bolt and a 5 bolt pattern on them (as alot of discs do, like the left one of ibizacupra's picture), you might find rotating them a hole would have given you your fifth hole.

There were a lot of holes! They did all seem evenly spaced, maybe I just needed to rotate more or something. Alas, it does not matter now!

 

[DPJ]

Not necessarily always the case, the disc could be designed to use rotational force to suck in air from the centre and disperse it outwards.

Interesting. Please expand.

 

[Ruddmeister]

Interesting. Please expand.

I will grab a mug of tea and hopefully learn something new too.....can't wait

 

[Slimy]

OK, I did write an overly complex description, then looked at it and thought 'I sound like a pratt'... so here's the edited version.

It is simply a case of centrifugal force, anything turning around a pivot will tend to be forced outwards. In this case, air.

The same theory works with Whirlies, http://www.exo.net/~pauld/summer_institute/summer_day13music/Whirly.html

 

[DPJ]

I could see that a disc would suck air in at the centre and blow it out at the circumference if there were fan type blades at the centre - but I havent seen any that have that.....

A wing creates lift because the air has further to travel over the top than underneath, but I'm struggling to see how there is high pressure at the circumference of disc and low pressure at the middle simply because the disc spinning.............

 

[DPJ]

Ok, I'll buy the Whirly explanation........ but if that was the main way the disc was cooled, why wouldn't the cooling channels be angled so as not to 'scoop' air' ..... ?

 

[Paul D]

That's actually correct, as most modern fans draw air through from the centre and collect it at the outer edge - so long as their is space for the air to enter/leave the disc at inner and outer edges it shouldn't matter.

I had a set of 3G discs on a previous car and was told by them that they could be mounted either way, but the curving forward would be a little more aggressive and would wear the pads faster, plus would be slightly noisier.