slotted or crossed drilled A8 discs wanted

[bertman]

Well some interesting reading there on this thread,sounds like I will stick with the standard A8 discs I have and save myself some money,which really should go towards paying off my huge bar tab
Been looking at various discs on the interweb and jeeezz there expensive,be even more expensive if they munch through the DS2500's I have on the car quickly

[stiglet]

I 100% agree with the above. Half the cars you see on track do not use cross drilled brakes.

Plus, now this may come as a shock to some, but Bugattis and Lambos aren't purchased by racing drivers. They are infact purchased by posers who like to talk about cross-drilled ceramic brake discs in the pub.

[coolhand]

Good to see some healthy banter and certainly for most daily drivers,non slotted or cast/drilled rotors will be superfluous.
It's true that pad outgassing isn't so much a problem with carbon-carbon brakes such as found on F1 cars (which aren't perforated axially, but ARE perforated radially) but a moreso a problem with metallic rotor/composition pad combinations.
The rotor gets hot enough under continual hard braking to literally vaporize the pad surface. Imagine an air hockey table and the puck floating on a cushion of air.
This type of process occurs when brakes get hot enough to vaporize the pad. To combat this slots are cut, or holes are drilled to bleed the gasses off before they can "float" a pad.

The distinct preference is for slotted rotors on high performance brake systems, to quote a couple of brake design engineers:

AP Racing
"Grooves improve 'cleaning' of the pad surfaces (anti-glazing) and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs."

Stop Tech:
"StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors."

There is a pretty informative and concise F.A.Q in the link below:

http://www.dba.com.au/2006/consdocs/C006.asp

From personal experience I would say that having my A8 rotors professionally slotted improved the braking feel/ability under repeated hard usage, but ultimately I went to the Porsche cast (not drilled) perforated rotors which were a much bigger improvement again, but I wont argue that it was the holes more than the fact that the rotors were considerably larger in both their diameter and width thus providing much greater braking ability on several accounts, and the bonus is that they are substantially lighter, again contributing very significantly !

[anton]

Good to see some healthy banter and certainly for most daily drivers,non slotted or cast/drilled rotors will be superfluous.
It's true that pad outgassing isn't so much a problem with carbon-carbon brakes such as found on F1 cars (which aren't perforated axially, but ARE perforated radially) but a moreso a problem with metallic rotor/composition pad combinations.
The rotor gets hot enough under continual hard braking to literally vaporize the pad surface. Imagine an air hockey table and the puck floating on a cushion of air.
This type of process occurs when brakes get hot enough to vaporize the pad. To combat this slots are cut, or holes are drilled to bleed the gasses off before they can "float" a pad.

The distinct preference is for slotted rotors on high performance brake systems, to quote a couple of brake design engineers:

AP Racing
"Grooves improve 'cleaning' of the pad surfaces (anti-glazing) and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs."

Stop Tech:
"StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors."

There is a pretty informative and concise F.A.Q in the link below:

http://www.dba.com.au/2006/consdocs/C006.asp

From personal experience I would say that having my A8 rotors professionally slotted improved the braking feel/ability under repeated hard usage, but ultimately I went to the Porsche cast (not drilled) perforated rotors which were a much bigger improvement again, but I wont argue that it was the holes more than the fact that the rotors were considerably larger in both their diameter and width thus providing much greater braking ability on several accounts, and the bonus is that they are substantially lighter, again contributing very significantly !

I can see what your getting at here but i'm almost cirtain the temperature at which vaporisation can occur will far exceed the temperature most street or track pads can get to, you would need race spec pads to acheive these temperatures. And then the pads should be able to withstand these temperatures. remember that the metal or ceramic pads, which is what is used today, when they 'vaporise' they will essentially be burning and giving off obvious smoke. obviously if your brake temps are at this level then you have bigger problems than the brakes 'floating'. Basically your trying to counteract something that should NEVER occur in normal use anyway. As for the the grooved discs reducing glazing, this is because the groove essentially works a a blade taking of a fine layer of the pad material which takes off the glazed layer, and yes this can improve the friction coefitient but will loose controll and give a more 'on' 'off' feel. also The more material it takes off(and therefore more friction) the more pad wear, to get a noticable improvement you would need to bring in conciderable pad wear, and this obviously isnt a solution as if your pads are glazing then more cooling is needed no matter what, grooved disc are simply delaying the effect of brake fade.

By the way the Radial perforations your talking about on the formula 1 carbon fibre discs are for cooling and cooling only as they are internal to the disc, they are there because conventional 'ventilated' type cooliing is not allowed.

as for those liks you ou posted need to read between the lines and remember that that is a sales pitch and as such includes a fair bit of b.s.

[stiglet]

F1 cars are most definately not cross drilled. They are vented, same as the car on my driveway outside. They are a different material yes, but they generate just as much heat as regular brakes.