WHY Blank rotors are better than cross drilled and/or slotted

murcielago

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f1 they using ceramic disc...i dun think they can drill holes n make slots on tat.....somemore ceramic can withstand high temperature and dun heat up as easily as steel...
always i heard is get slotted disc is good enuf n drilled disc can easily cracked....
 

Battousai

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In F1, I'd assume they put a huge amount of R&D into their pad compound so as to not produce gas and dust. Therefore, they can run a solid disc.

Personally, I think upgrading to steel braided brake lines, performance pads and good brake fluid is enough.
 

SkYwAlKeR

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i thought ceramic brakes has slotted and crossdrilled type one??.. coz i saw the brakes in ferrari/porsche in best motoring... their ceramic brakes also slotted...
 

TitanRev

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Eh..guys. This theory just struck me in the head when i was taking bath yesterday.
Anyone with my age or older than me would remember this. When i was a child, my grandmother or grandfather would teach me to poke holes in a bowl of rice to cool it down faster or make a hole in the center to cool the rice faster. I do think that this theory applies to the brake too.

2 steel block that has a same mass and dimension but 1 is drilled with holes which one would cool down faster ? the one with holes rite ?

Why ? because more heat can be transfer to the ambient air. Heat can be transfered from the surface to the air and heat inside the disc can be transfer to the holes and air thus provide better cooling. If only a blank rotor heat can be transfer to the ambient air too but heat transfer only happens on the dics surface heat inside the disc will have to wait the surface to cool down to transfer more heat to the surface.

there are 4 principles in heat transfer.
one of the principle is (Heat is ready to flow or pass to anyhing that has less heat.)

So what i think is the holes in the disc surface is to remove heat at a more faster rate because ambient air is definitely cooler than the temp created by the braking force.
If a brake temp is too high, brake fading will happen and it may cause the dics to bent due to the high temp. We know that metal is hard to bent when its cold but when its heated to a certain temp it could be bent much easy.

Another thing is with cross drilled or slotted, we can increase the working temp of the brake system. With faster heat dissipation rate we can get a better or higher working temp.

Just like why some cars install oil cooler. oil cooler will keep the oil cool so that you can rev much higher and the oil can sustain a more severe driving condition without overheating. If the engine temp is too high, efficiency will drop. Just like our brake, if its too hot it's efficiency will decrease too.

Just my own 0.0002 opinion only. No hard feeling guys.:biggrin:
 

Joeker

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First and foremost, the rotors being compared has to be parrallel.

How on earth can one compare a full race composite compound blank rotor to a cross drilled and slotted street rotor?

It would be like testing the performance of a jet engine against a Columbia shuttle rocket engine.

A fair comparison of braking efficeincy would be a blank street rotor against a cross drilled and slotted street rotor.

In other words, compare apple with apple.
 

tk2005takeru

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Comparing $#!+ with Chocolate...

Braking under normal condition and braking under wet condition, how can I say, need to see the skill of the driver... Who would lock their brake when coming to a patch of water on the road?? And also when the disc brake is hot enough, the water will vapourized if kena water... I dunno much about technical stuff, so correct me if i'm wrong, but i still know physics...
 

boggysv

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tk2005takeru said:
the water will vapourized if kena water... but i still know physics...
:biggrin: yes sir...you do know your physics.

Most track junkies prefer slotted/grooved/dimpled rotors.
However, the original writer (redline96lx) is very naive in his arguement. And apparently forgets basic common sense.

If your stopped, you are leaving air inside these holes sandwiched between the pads, thus creating air with a rising temperature. Its increasing in pressure from the heat, which I guess you "could" call a gas that would affect braking.
Hot air raises genius. Moreover, when your rotor is spinning, air gets blown out throught the spinning vents. Even in grooved/dimpled rotors, air is not going to stay there to continue getting heated.

When stopped or moving, the pad transfers heat into the rotor because its made of cast iron.
Heat flows from areas of high temperature to areas of low temperature. There is no definite direction between the pad or disk. Disk are usually cooled better, and hence they usually take away heat from the pad. Have you seen cooling fins on brake callipers?

Don't believe me? Touch some steam at 150 degrees, then touch a piece of hot metal which is at 150 degrees. Which burns your hand? the metal.
Unless you plan to keep your hand in prolonged contact with either choice, 150degrees steam will "burn" your hand more. Heat transfer is much much faster. 150% metal can store more heat energy, that's all.
The original aim for slots/holes on brake disks are not to store heat, but instead to lose heat. I'd galdly trade off that small loss in thermal capacity for the increased heat dissipation.

Even Porsche and Ferrari will admit that the cross drilled rotors they use are for looks.
Link/proof please.

Find me an F1 car as of now that uses cross drilled or slotted rotors.
They all use full ceramic rotors and ceramic pads. Are they drilled or slotted? No. If they helped the fastest cars in the world, wouldn't they use them? Its basic calculations that show the lack in surface area does not make up for the possible loss in temperarure. They use brake cooling air ducts insted.
They use brake cooling ducts because it lets them control brake cooling easilyby switching duct sizes. Moreover, F1 brakes need fairly high temperatures to operate, which in that case, only a solid rotor would be structuraly safe. (most of us wouldnt even reach those temperatures on a daily basis anyways.) 24hr leman cars use slotted/grooved disks, jgtc cars use them, alms cars use them, wrc cars use them.

then you have a better brake setup because you have OEM parts
Sure....I'll take my stoptechs, alcon, and brembo, prosche...you take your acura RL setup. Lets see if you can outbrake me.
 

sam1741

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gavan said:
i do not agree with sam's opinion as i was riding a motorbike before, full disc...and the braking was not too good when it was wet. even both my disc was cross drilled, the bike was not braking too good when it was wet and cold, but once apply some hard pressure on the brakes and the disc heats up,the braking improves so erm, beware when you are riding fast and your brakes are not working, just apply light preesure till the disc heats up then the braking will improve



will elaborate more when im home
HKS-GT2835R said:
agreed..my bike got cross drilled double disc up front, and it sucks when wet.

when heated up properly, say..2~3 minute of riding, then it'll be a BIT better.

my guess it's due to stainless steel discs. cast iron rotors are better in wet.

hahaha
honestly.. my bike's disc also got holes
also suck when it wet... sometimes scares me only..

but i beleive the braking power 'come back' faster then blank disc...
i cannot proove lar.. cause i not ride with bike with blank disc before
but i have seen some older bike that is using blank disc
maybe i should borrow some to test someday.. :D :D
 

sta

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brake performance decrease when raining because your tyres canot grip, nothing to do with brakes
 

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