Imao sam bušene, sad imam obične - općenito, glasam za obične ili narezane.
Te fore sa "ventiliranjem plinova" i "boljim hlađenjem" bušenih ŽELJEZNIH diskova su netočne, današnje pločice razvijaju puno manje ili ništa plinova, a priča je započeta pred 50ak godina u Formuli 1, kad su korištene potpuno druge kombinacije materijala. Na karbon i keramičkim diskovima rupe su (pretpostavljam) korisne, budući da ih skoro svi egzotični auti imaju. Vrlo brzo nakon montaže diska rupe se gotovo začepe prašinom, toliko o "prozračivanju" i "hlađenju".
BTW, hlađenje funkcionira prolaskom zraka u radijalnom smjeru (usis u srcu, izbacivanje prema obodu), ne "propuhom" kroz disk.
Glavna prednost bušenih diskova je MANJA TEŽINA:
- manje neogibljene mase (udobnost+upravljivost)
- manji moment polarne inercije (ubrzanje-kočenje)
Iz istog razloga postoje mane - manji termički kapacitet, lakše stvaranje pukotina (lokalne točke napora materijala).
IMHO, ako stavljaš veće od tvorničkih diskova (pa bušenim diskovima smanjiš dodanu težinu), ili ako ti ne treba bolje od serijskih performanse a sviđa ti se "look", uzmi bušene.
Ako su ti bitne performanse, a ne smeta ti gubitak trajnosti pločica i udobnosti (ponekad buka), uzmi rezane.
Ako su ti bitne performanse, ali bi hrio zadržati trajnost i udobnost, uzmi pune diskove i čim bolje pločice.
Postoje i "dimpled" tj. diskovi s kružnim udubljenjima, izgledom glume bušene, a imaju dio prednosti rezanih (djelomični deglazing pločica).
Ima puno toga na googlu...
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Slotted rotors improve stop-to-stop consistency by preventing reduction in friction from pad outgassing and lubricating brake pad particles (also called "incandescents") which are otherwise trapped between pads and rotors. Pad long-term performance is also made more consistent, as slots shave away glaze formation caused by pad overheating, slowly exposing fresh pad material each time the brakes are applied. The tradeoff is slightly reduced pad life. Although modern pad compounds make this less important, slots offer improved bite and slightly higher friction level than smooth rotors.
Where allowed by rules, slotted rotors are by far the top choice for competition vehicles. These are the best choice for heavy trucks and SUVs, particularly when extra bite is desired for towing, especially when aggressive pads are not available.
Disadvantages include slightly reduced pad and rotor life, some low frequency rumble and pedal flutter when braking hard from high speeds. If the slots are improperly machined, all the way to the outside edges, then rotors may develop cracks sooner than plain or properly slotted rotors.
Drilled rotors offer slightly more bite and friction than slotted rotors. As with slotted, pad coefficient of friction remains more consistent over their lifetime. Wet bite is better than plain or slotted rotors, so these may be the best choice for areas with frequent, heavy rainfall, like Seattle or Singapore. Weight is reduced by about 0.2 pounds per rotor, depending on size and drill pattern.
Disadvantages include possible uneven rotor wear, typically concentric groove formation, although this is mostly an aesthetic concern. A major disadvantage is accelerated formation and spreading of cracks under racing conditions. For this reason, drilled rotors should be avoided for track cars, unless required by the rules. A common myth is that they have lower performance than smooth rotors, due to reduced surface area and are for looks only. This is completely false and, in fact, the opposite is true.
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The reason big companies still produce crossdrilled rotors and have them on their cars is because most people are clueless sheep. Most folks don't know why rotors were originally cross drilled. They don't know why race teams won't use them. All they know is that from way back in the day, a true sportscar always had crossdrilled rotors (back in the day when brake pads sucked).
You want to know why 'sportscar' companies still put drilled rotors on their cars? An insider who was actually involved in the actual testing of the brake rotors fessed up about it. They conducted tests with plain and drilled rotors and concluded and confirmed that the plain rotors had no downsides and in fact were better in hard braking than the crossdrilled rotors AND would save the company a little money not having the crossdrilled option. And when they put them on cars, customers commented that, "For a performance car, they should have at least gone through the trouble/expense of putting on high performance crossdrilled brakes". They realized that this is the general public perception, so even though they had concluded that the plain rotors were better, they put crossdrilled rotors back on the cars. If that's what the public thinks and wants, that's what a good business provides.
