Rioja

I'm on my second set of grooved disks, and have fitted them with the outer edge leading: on my previous set I fitted the outer edge trailing. I haven't noticed any difference in overall performance, although initial bite seems a little better.

Does anyone have any thoughts on a right/wrong way to fit grooved disks, a performance benifits of either?

Cheers

timmyajmy93wrx

iTrader: (27)

i bought the tarox 20 groove they have to be fitted in a set direction, could have something to do with the heat dispersion from the disc/pads?

tim

tath

surely you want the grooves so they take glaze from the disc and 'dump' it at the edge when the wheel is going forwards??? in the same way directional tyres take water from the center and spread it out to the edge?

dazc

The direction of the grooves is largely irelavant, varies with each manufacturer, and even sometimes with the same manufacturer, (AP for instance).

What you should be looking for is the vanes inside the disc if it has them. These should sweep backwards from the middle of the disc effectivley throwing hot air out of the vented part of the disc as it rotates, rather than scooping air in.

If it doesn't have vanes (or fins) inside the disc (some don't) I would agree that having the grooves pointing backwards at the top of the disc is the way to go, throwing the gasses out to the edge as it rotates.

Daz

Rioja

Cheers for the comments guys. The disks are 'Sport Japan' by Tarox, and like I say my second set. I haven't looked at the direction of the internal vanes, but do know that the vanes run through the disk and exit at the centre of the hub ie, not closed. I am now wondering whether the vanes are designed to draw air from the outer edge and vent at the hub, or draw it in at the hub and vent at the edge; as per Dazc's comment: the disks are also cross drilled that may have some effect on the process?

I have always thought the grooves were to de-glaze the pad and allow any gas build-up between pad and disk to vent, so a 'trailing' groove would seem logical. However, I've looked at some compitition cars over the years and the direction seems to vary; some aren't even handed, with trailing and leading on the same axle (although always been rears!)

Chelspeed

Air flow is always in from the hub and out from the outside diameter, as the wheel turns the air is "pumped" through the disc, thrown to the outside by the rotation of the wheel.

What's far more critical than the groove direction is the shape of the air passages thro the disc.

Cheap discs have straight passages with the dividing wall between the centre and outside dividing the disc into triangular sections, sort of like slices of cake. With straight vanes the discs can go either way, this way you can choose whichever groove direction you prefer.

Proper discs have curved passages that act like a cetrifugal pump impellor making the air flow through the disc more efficient. See here for a pickie. With this type the curved passage must sweep backwards from the hub to the outer edge. You must mount them this way for them to stay cool properly, groove direction is then decided by the disc maker.

Rioja

Chhers, that appears to have settled it then.