Why do 'supercars' use cross drilled and not slotted brake rotors

[marklee]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Ferrari improves front wheel fairing - F1technical.net

The static wheel fairing helps a lot for the F1 cars, but who's gonna put it on a production car and try and sell that ugly thing? haha

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Actually these discussions are good. They made me realised that almost every track car, from Porsche to BMW to Ferrari failed in their brake designs..... quite a revelation......

No need for sarcasm man.. just make some points

BTW, most Porsches, BMWs, Ferraris, are not track cars. They are sporty road cars. Take most of them for a few consecutive hot laps at a taxing circuit and things start to fail. That's why you don't look to them to figure out what to do. They are made for profit. Highest perceived value, greatest customer satisfaction, lowest cost... greatest profit.

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

The bigger your rotors are the faster you'd be able to stop.

Unless the weaklink is the tires or pads. Interface temperatures and friction levels..

The only problem with heat is that your rotors wear away quicker, as Shaun mentions above.

That's mainly a problem with carbon carbon stuff where heat kills both rotor and pad. With good cast iron rotors, overheating most often kills the pads first.

 

[kenntona]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

No need for sarcasm man.. just make some points

I really think you have a problem with me.

These were the points purported by you, and now I am slapped with a "sarcastic" remark when I am agreeing with you?

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

The bigger your rotors are, the faster the heat is dissipated from your pads to the rotors also.

Not really, and only unless the rotor is at a low enough temp to start with. Even then the effect is pretty small vs the actual generation of heat energy. It's like skiers who fall on ice and have the rubber suits still melt. The ice didn't really help conduct the heat away that was generated, although falling on warm asphalt would have been worse.

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

I really think you have a problem with me.

These were the points purported by you, and now I am slapped with a "sarcastic" remark when I am agreeing with you?

No problem, I just thought you were being sarcastic. Better to reply to existing points, or make new ones.

The three makes that you mention, did not screw up on their brake designs. They're too smart to do that. You know that all this is too simple for them. They simply made a conscious decision for profit and to design the car to fit 99% of the people who buy them. The other 1% have to take care of the car themselves and upgrade them to take abuse. Production road cars rarely, if ever, are track cars, no matter how much they cost or how they look.

 

[TripleM]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

As I understood it, breaking was all about friction and leverage. So

The faster you can turn kinetic energy into heat energy the better; and
The bigger your rotors are the faster you'd be able to stop.

The only problem with heat is that your rotors wear away quicker, as Shaun mentions above.

0.02c

U got KERS Marc?
I want one..........

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Ferrari improves front wheel fairing - F1technical.net

The static wheel fairing helps a lot for the F1 cars, but who's gonna put it on a production car and try and sell that ugly thing? haha

It wouldn't even be considered on a production car cos of the costs involved and how small the gains. No one pays thousands of dollars for a few thousandths improvement on a production car.

 

[kenntona]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

For a layman, it really surprised me to see M3 CSL running on cross-drilled stock rotor while the non-M cars running solid rotors..... counter-intuitive for a track car to use a more "inferior" rotor design.......

 

[Girettom]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Finally, I found an image that was large enough to figure what the ALMS guys are running on the M3.

http://image.modified.com/f/car-new...1+re0+ar1/rahal-letterman-bmw-m3-alms-gt2.jpg

(This is a really large pic... slow download)

The rears are actually drilled, and the front are slotted... but they are those curvy slots. Shaun... you got a view??!

 

[Girettom]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

U got KERS Marc?
I want one..........

no recovery at all... just straight off at the corners (or in the back of toto if he doesn't get off the track fast enough)

 

[marklee]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

It wouldn't even be considered on a production car cos of the costs involved and how small the gains. No one pays thousands of dollars for a few thousandths improvement on a production car.

Are the gains from the additional cooling to the brakes really that small? I thought these wheel fairings not only provide cooling for the brakes but also reduces drag on the wheels and also allows for smaller brake ducts, further reducing drag? I wouldn't know..

Come to think of it, consumers do pay thousands of dollars for a perceived improvement on a production car, when there actually is none. If in another reality, that wheel fairing was somehow deemed as a fashionable aesthetic mod which provides some form of function to the car, you would see it on production cars. e.g huge ass spoilers, which does more harm than benefit to a production car

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Ken, guy walks into BMW dealership and looks at the M car sitting there next to the other cars... thinks "wow look at those bulges.. look at the brakes even.. they're like Porsche brakes. Man that car has to be special" buys it and yah it works fine for all his country road drives and pottering around town.

===

Marc yah.. show car, not as run. Look at the livery on the car and the location of that photo. Got an actual trackside race pitstop shot?

Even if it is as run, the other very possible reason is related to the first para to Ken.. BMW NA knows the ALMS demographic and how closely their racecar is tied in public mind to the production road cars they sell. Martin Birkmann has said this in interviews. The front takes most of the braking load and it gets too expensive to keep replacing rotors up front, or cos of the nature of the racing they do (endurance), the drilled stuff affects performance. So they think "ok we'll compromise and put the drilled stuff where it'll live longer.. in back.. and our fans will see that at least it is half like the road car in terms of brakes".

They may also only run that config at most of the shorter events and get it into public mind. At the longer events like Sebring 12 or PLM 1000, might be all slotted.

And still GT2 is far from the most stressful automotive brake app in the world.

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Mark, it is the cost of the gain that is astronomical, plus the gain is small. When the wheel fairings first came out there wasn't a big noise about them being critical to victory unlike with the recent diffuser. And it costs lots of properly integrate with the rest of the aero. Road car aero is so compromised to start with.. and they almost never have proper brake ducts anyway.

===

Anyway it is almost dinnertime and there will be no convincing going either direction.. all this is just waffling. All I can say is look for the top 5 - 10 arenas / groups internationally that really run their brakes hard.. and that aren't limited by rules and aren't sponsored by compromised brake company. Look at the brakes they run.

 

[Ahbengdriver]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Wah.....I learn so much today, about brake rotors. Gonna sleep well.

 

[Racebred]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

my freaken S-class also got cross drilled rotors. And its not even sporty. As usual, the holes all got plugged up with grime, and every one of them crack.

 

[Racebred]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Are xdrilled rotors from porsche, ferrari etc really cast with the holes in them, or is it a myth? Does it really make a significant difference whether they are cast with holes or drilled after casting as blank rotors?

most of them just OEM from the prominent brake brands, for their high-performance lines of cars. Unless the production line from the brake companies are changed, I dont think these rotors are any different from what you can buy as an aftermarket upgrade.

 

[centurion]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

I have both slotted and cross drilled right now installed. Also I have driven S2K in both slotted and cross drilled configuration with same pad. But I dunno whether it is same manufacturer or not, so take this as anecdotal.

Slotted rotors are ROUGH! I am using street pads with my slotted 325mm JBTs, and I can feel EVERY slot brush against my pad on gentle braking and moderate braking. Of course, HARD braking I don't feel anything until I pressure off.

The cross drilled is FAR more comfortable.

If you use REALLY BIG rotors, it best be slotted I think. I wore the 298mm stock cayman 2.7 xdrilled front rotor until they were 4mm down (factory says replace on 2mm down). No cracks. But from what I read here and other forums, big rotor crossdrilled expensive stuff, many cracked.

That being said, I have also seen rotors with no slots and no holes crack .....

 

[TripleM]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

yeah..many times we may hv forgotten on the severity of the usage and often enough, dont understand the combination and fail to perform our duties to maintain the brakes..
eg..highly abrasive pads for street driving that reap the rotors life
also when brakes are too hot and wash the cars. Repeated habit will probably shorten the life too..

 

[Shaun]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

Finally, I found an image that was large enough to figure what the ALMS guys are running on the M3.

http://image.modified.com/f/car-new...1+re0+ar1/rahal-letterman-bmw-m3-alms-gt2.jpg

(This is a really large pic... slow download)

The rears are actually drilled, and the front are slotted... but they are those curvy slots. Shaun... you got a view??!

Marc, someone recently bumped an ALMS thread on here and on it there is an actual photo of the Rahal Letterman M3 in actual track testing. It is not a press photo for Rays or Volks wheels like the one you posted.

Anyway one of the photos is this one http://farm4.static.flickr.com/3129/3235511656_755e04dc10.jpg

and it can be found in high resolution over here, along with many other closeups of both the front and rear brakes as run. BMW M3 GTR

So my view might have been correct

 

[marklee]

Re: Why do 'supercars' use cross drilled and not slotted brake rotors

The rear rotors look bigger than the front?