Drilled RS2 disks & ATE super racing blue

[dan_b]

Holes = bad in my book.

[alg]

DS 2500 front excellent. However on the rear why???

Drilled discs pointless fashion accessory, had them on the S2 but the holes simply fill with dust

[dan_b]

To my mind:

Drilled discs = increased stress points = increased risk of disc cracking
Drilled discs = reduced thermal capacity of disc vs. plain faced disk = increases pad/disc interface temperatures = increased risk of brake fade and overheating pads

You don't see drilled discs on proper racing cars: F1, GT, Rally or Touring Car. They must know something.

As you say, I'm sure they don't really provide an effective dust-expelling route as they block up rather easily, and modern pads don't even out-gas much (at all)?

It's just for looks IMHO. Happy to be proved wrong of course, but I don't believe they offer a genuine performance improvement for the above reasons.

DS2500s on the rear? Why not? If you're changing pads anyway, you might as well, especially if you've got them on the front?

[charlie]

Everybody is entitled to their own opinon. So what is wrong if they
are a fashion accessory. Lets be honest, so is most of the things in our
lives, homes, offices, holidays, the list is endless. :mischeif:
People say that their is no evidence that it improves performance, but on the other hand, it doesn't deter performance either
And for the holes blocking up, nothing a jet was or an air line couldn't clear
out. Chillout guys

[dan_b]

I'm chilled :cheers:

[alg]

Everybody is entitled to their own opinon. So what is wrong if they
are a fashion accessory. Lets be honest, so is most of the things in our
lives, homes, offices, holidays, the list is endless. :mischeif:
People say that their is no evidence that it improves performance, but on the other hand, it doesn't deter performance either
And for the holes blocking up, nothing a jet was or an air line couldn't clear
out. Chillout guys

Agreed However I got sick of getting soaked with the splash back from the jetwash when trying !!!!!!!!!!!!!!!!!!

[Lee]

Drilled disks do promote cracking due to the stress raisers in an already highly stressed part. They also reduce the effectiveness of the disk. It is a heatsink and mass has been reduced leading to a higher temperature rise for a given heat input. School Physics.

Definately a fashion accessory. Would never used drilled disks on mine because they would take the abuse.

I was still waiting for your explaination about different pads eliminating cracking mentioned earlier in this thread. Yes you can chose a pad that puts less heat into the disk and more into your fluid but then you are looking at higher fluid temps.

I guess if you don't use your brakes seriously hard then drilled will be fine and bling.

[Pete_RS2]

These discs are same as Porsche OEM parts aren't they ? Surely cross-drilled discs can't be all that bad if they're used by Porsche ?

[Jamo]

These discs are same as Porsche OEM parts aren't they ? Surely cross-drilled discs can't be all that bad if they're used by Porsche ?

They are a bit of a fad, as they tend to suffer micro fractures at the drill points causing cracks in the disc.

Manufactures are moving away from full drilled to holes cast in the discs.


Personally i've had some and i find grooved discs better IMHO

[Lee]

cast disks with cast holes does reduce the stresses marginally but not a great deal of difference in practice. Once you have a disk cycling through a few hundred degrees its going to crack no matter how the holes are made..just a matter of time.

[Lee]

Just because Porsche fit drilled disks as OEM means nothing. They are a fashion accessory (ie Porsche) at the end of the day and you will only find a small proportion are used in the way their image suggests (thrashed). Drilled 'looks' sporty and thats all Porsche wants...marketing at work.

You won't find many drilled disks in motorsport and if you do it is likely for degassing pads. Modern road pads do not gas.

[SR71]

Drilled disks do promote cracking due to the stress raisers in an already highly stressed part. They also reduce the effectiveness of the disk. It is a heatsink and mass has been reduced leading to a higher temperature rise for a given heat input. School Physics.

Not disputing that Lee but if I were a brake engineer I'd size up the volume of material I required to do the job and then look for a way to maximize its surface area.

Surely thats why cross-drilled rotors exist?

[S2Roo]

Cross drilled discs are not a fashion accessory. Nor are they for dust or heat dispersal. The cross drilled is to allow gas to escape that is generated when the pad material gets hot. With a non cross drilled disc the gas sits between the pad and the disc reducing the braking force. The cross drilling allows this gas to vent.

F1 cars have not use steel as a brake disc material since the 80’s, and use different pad material to that you would find on a road car, so this comparison is unfair.

Rally and Touring Car have, and do use cross drilled discs, depending on what materials is being used. I have seen these both at the welsh rally this year and at rallycross at brands hatch.


Roo

[Lee]

Yes there is a ratio of surface area to mass to consider but the holes are not there for cooling. Their [holes] net effect on cooling is insignificant when compared to the forced convection through the central vanes and the radiated heat transfer from the disk surface. Maximise mass reduces overall temperature rise for given heat input.

Drilled rotors exist because they look bling and sporty nowadays. From a material science and mechanical engineering perspective they make little sense. They were needed decades ago but pad formulations have meant the need for holes are pretty much redundant in modern brake systems. The image is still there.

If I drilled my disks I would have reduced performance and reduced disk life (everything else identical). My disks are huge (362x36 ~8kg) and regularly get to 700deg C on the street and track so the thermal cycling would definately lead to cracks on a drilled version.

[Lee]

Cross drilled discs are not a fashion accessory. Nor are they for dust or heat dispersal. The cross drilled is to allow gas to escape that is generated when the pad material gets hot. With a non cross drilled disc the gas sits between the pad and the disc reducing the braking force. The cross drilling allows this gas to vent.

F1 cars have not use steel as a brake disc material since the 80’s, and use different pad material to that you would find on a road car, so this comparison is unfair.

Rally and Touring Car have, and do use cross drilled discs, depending on what materials is being used. I have seen these both at the welsh rally this year and at rallycross at brands hatch.


Roo

Modern street pads do not 'gas'. Some race pads do: this is the only reason for them being fitted to some competition motors.