AP slotted brake discs

[anonymous-user]

Fitting the AP kit to my car - which way around are you supposed to fit slotted/grooved discs?

Taking the drivers side for example - the wheel rotates clockwise - I would assume that as the slot passes over the brake pad, the slot should move from the centre of the disc, towards the outer edge of the disc, so as centrifugal force throws out the brake pad dust. Put another way, if you look at the top of the drivers side disc, the slot will be leaning to the left, moving from the centre of the disc to the outer edge. But i could be wrong - I've tried looking at some web photos of slotted discs - a bit hard to tell, but some of them seem to go the other way. There is no direction of rotation markings on the discs.

Help! I wanna get the job finished tonight!

[i just want one]

You are correct, the groove goes from inner to outer to take dust and air out. All though I have seen so many cars with them going the other way(wrong)way. Remember to bed them in properly.

[pomona]

AP Racing Disc identification publication P14.047/99 shows slots going from OD to ID and cooling slots/vanes opposite to rotation,with vehicle in forward direction.

[anonymous-user]

Yes - if you fit the disc as I said earlier - slot going from inner to outer with rotation - the cooling vents don't look right. If the disc is fitted the other way - the vents will draw in air for cooling. I'm right in the middle of the job now, it's quite easy to swap over the discs - just remove the caliper, so which is the right way around ???

I'll post up some pics of the disc shortly .... I need to make a decision !!

Thanks for your help guys



>> Edited by anonymous-user on Thursday 28th October 21:14

[GreenV8S]

Ignore the grooves, fit it so the vanes are the right way round. If your vanes are not handed (i.e. purely radial rather than angled) it doesn't matter which way round you fit them. With radial vanes the rotors are often not handed i.e. left and right rotors are identical so the grooves go different ways on each side.

[anonymous-user]

frigging' laptop has died and wont power up .... and my office PC wont talk to my sony camera .... aagghh! .. so I can't post pics

The air vents ARE angled, so, unless I hear otherwise, I'm going to fit the discs so that they draw air into the centre of the disc as they rotate. This way around, the grooves run from the outside towards the centre of the disc, as they rotate. Seems strange, I wonder why they are that way around??

Thanks again.

[GreenV8S]

GSE said:

I'm going to fit the discs so that they draw air into the centre of the disc as they rotate.

Not sure if I've misunderstood you, but that seems to be the wrong way round. The vanes should be oriented so that they run from the inside to the outside in the direction of rotation as shown here: www.apracing.com/car/brakedisc/identification.htm

It is not at all important which way the grooves run. They are normally angled to reduce chatter as the leading edge of the pad runs past the groove, but it doesn't matter which way. They are not there to pump air, just to let gas escape from under the pads. I guess there may be structural reasons to have the vents and grooves angled in opposite directions, but there aren't any performance reasons that I'm aware of.

[stevieturbo]

Grooves are irrelevant. Ive just got my new set of AP's for my car, and the grooves are the opposite way round from my old ones.

Fit so the cooling vanes are the correct way round. ie draw air from centre, expelling it on the outside of the disc

My discs were boxed left and right.

[anonymous-user]

Job done - everything has fitted on ok. Just have to bleed the system tomorrow morning, then I'll have the rest of the day to go for a long (gentle) run to bed them in

Stevieturbo & Green V8S - thanks for the info & link - I have one set of discs on one way, and the others on the other way at the moment, so I only have to swap around one pair of discs tomorrow am.

>> Edited by anonymous-user on Friday 29th October 01:02