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Dimpled Rotors: dont do jack-poo. the only thing that dimpled rotors do, is release a tiny bit of the gasses that builds up between the rotor & pad. but since its such a tiny dimple each, its not even worth the extra money. think of how many CC's from a syringe would fill each tiny dimple. worthless. best to take that money and invest into better pads. its made to resemble cross drilled rotors - and thats about it. plus, as the rotor wears so does the size of the dimple. (see picture below)
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Cross-Drilled: is a whole different story. they actually vent any gasses between the pad & rotor, and also allow air to cool the rotor itself. the only problem with cross-drilled rotors is two fold. how its made (cast with hole, or drilled after casting). the more expensive rotors are cast with the holes, which are then refiled, and smoothed out. the cheaper rotors are all solid core, and THEN drilled. the drilling causing the metal to become more brittle. and you know brittle rotors spinning while heat cycling (contracting & expanding) is awful, and a disaster waiting to happen. IT CAUSES STRESS FRACTURES NEAR THE DRILL SITE(see pictures below)
(cross-drilled continued)
now modern science has done plenty testing to state the follow: either casting, or drilling = it still produces stress fractures in the rotor itself because essentially its a full hole, through metal that goes through extreme pressures & heat cycles. In fact, I have a BRAND NEW BREMBO OVER-SIZED TWO-PIECE “FLOATING” ROTOR THAT HAS NEVER BEEN USED = STRESS FRACTURES SO LARGE, ITS NOT EVEN FUNNY. ITS BEEN MY MONITOR STAND FOR 5 YEARS NOW. WORTHLESS. So that tells you how sensitive these things are. somewhere in transport to and from its destination, it cracked while in the very well packaged box. (see pictures below)
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SLOTTED ROTORS: (can be found in curved, or straight) these in my book and in many books, is the best rotor for the buck to get. it causes a HUGE bite on the pad, (which causes faster pad wear, and more dust) but it works very well. its like sliding your finger across a cheese peeler. its unreal the stopping force these types of rotors will have. plus, they are not fully drilled through, and they vent because the actual slot extends PAST the break pad surface. (see pictures below) you can see that there is just a fraction of an inch on both ends of the slot that never comes into contact with the brake pad surface, so the slot not only aides in the bite, but it also works as a channel for the hot gasses to vent out - which helps the brake pads stay cooler and reducing glazing/melting/etc.
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JUST WHEN YOU THOUGHT THAT WAS IT?
J HOOK: this is a revised slotted design. its actually less appealing to the eye - but its THE BEST FOR PERFORMANCE, HANDS DOWN.
This design was used in Le Mans, Nascar, SUPERGT, etc. These are noisy, will make more brake dust, but this is BALLS TO THE WALL, TRACK STUFF. The idea is, that it cuts/shaves the brake pad face differently every millimeter as the J hook passes the surface of the pad. that reduces glazing, and the typical bump-bump-bump design in the rotor as the same spot touches the same portion of the pad, in the same way.
Slide your finger across the J Hook and you will see that at it will touch different parts of your finger, at different times - and the next hook wont pass the same spot anymore - but half will be cut in the same location. it basically acts like a confusing shaver to the brake pad. really cool physic's stuff.(see pictures below)
