Drilled/Slotted Rotors

[coldkilla]

Originally Posted by curt86iroc

FYI, mass does not transfer heat. the surface area of the pad and the material properties are the deciding factors in the heat transfer. that being said, drilled rotors will cool better because they allow forced convection via turbulent air flow to exist between the rotor and the pad. the holes cause the air flow around the rotor to "trip" turbulent. turbulent flow will always transfer more heat than laminar.

wow, where did you go to school? i thought that this was a basic element of brake theory that everyone understood but apparently not. the surface area of the pad has absolutely nothing to do with heat transfer in the manner that you are speaking of. the pad creates heat by rubbing against the rotor, turning friction into heat. the rotor, in turn needs to effectively handle this heat and dissapate it. THE MORE ROTOR THAT YOU HAVE, THE MORE HEAT IT CAN HANDLE BEFORE FAILURE AND IT CAN DISSAPATE THIS HEAT FASTER BECAUSE IT HAS MORE SURFACE AREA. once you start cutting holes and slots in the rotor, you are taking mass away and you now have less rotor. this is not opinion or conjecture, this is fact. someone made the analogy of boiling water. put just a small amount of water in a pot and boil it. now put a lot of water in a pot and boil it. the pot with less water will boil first because there is less water to soak up the heat. the same principal works with rotors, why do you think rotors are so damn heavy? they are made with enough mass to effectively soak up the heat and dissapate it before they become heat soaked and ineffective. as far as real world results, which is better, blah blah blah. i dont care, whatever makes you happy, just dont turn this **** into voodoo as its really quite simple.

[11 Bravo]

The cross-drilling, is worth more than poseur points; it actually helps the brakes work better. Under hard braking, a brake pad's bonding agents burn off and produce gases. Cross-drilled holes allow those gases to vent, helping to prevent brake fade. Also, when water contaminates the rotor's surface, the holes allow moisture and muck out rather than causing the pad to "float" over the surface of the rotor. Cross-drilling also improves rotor cooling, again defeating brake fade. On cross-drilled rotors, temperatures can be reduced by as much as 200 degrees during extreme braking when compared to stock rotors. Since braking is essentially the absorption of a moving vehicle's kinetic energy and conversion into heat, rotors that quickly and efficiently dissipate heat perform better. Cross-drilled rotors increase rate of heat dissipation by decreasing surface area, allowing gases to escape, and increasing air flow.

[rgaynor85]

it still comes down to yes they cool better and dont warp if they didnt race cars wouldnt use them.

[curt86iroc]

Originally Posted by coldkilla

wow, where did you go to school? i thought that this was a basic element of brake theory that everyone understood but apparently not. the surface area of the pad has absolutely nothing to do with heat transfer in the manner that you are speaking of. the pad creates heat by rubbing against the rotor, turning friction into heat. the rotor, in turn needs to effectively handle this heat and dissapate it. THE MORE ROTOR THAT YOU HAVE, THE MORE HEAT IT CAN HANDLE BEFORE FAILURE AND IT CAN DISSAPATE THIS HEAT FASTER BECAUSE IT HAS MORE SURFACE AREA. once you start cutting holes and slots in the rotor, you are taking mass away and you now have less rotor. this is not opinion or conjecture, this is fact. someone made the analogy of boiling water. put just a small amount of water in a pot and boil it. now put a lot of water in a pot and boil it. the pot with less water will boil first because there is less water to soak up the heat. the same principal works with rotors, why do you think rotors are so damn heavy? they are made with enough mass to effectively soak up the heat and dissapate it before they become heat soaked and ineffective. as far as real world results, which is better, blah blah blah. i dont care, whatever makes you happy, just dont turn this **** into voodoo as its really quite simple.

how do you think the heat is removed from the rotor? not through mass "soaking up heat " but by pure convection. why do you think high performance cars have brake ducts that force air directly to the rotors??

forced convection with turbulent flow will transfer more heat than forced convection with laminar flow. like i said above, as the rotor moves through the air, the holes will trip the air turbulent pulling more heat off of the surface. simple fact found in any heat transfer book. im not trying to be cocky, im just stating the laws of convection.

[Ian]

I agree with curt. you also have to think of radiators as another example of heat transfer. Heat will escape from metal at the edge better than from the middle of the material. Fins on radiators are what make them effective. the more fins or edges you have, the more heat will get transfered. Similarly, the more edges you have on a brake rotor, the faster it will dissipate the heat it absorbs. the holes drilled into the rotor create more edges for the heat to escape and also provides more area for air to pass through, aiding in heat transfer even more.

another common item you can look to for an example would be a heat sink. they dont make them into a solid block, they give them as many edges as they can. why? because heat escapes the parent metal faster through edges where the metal is surrounded by more air.

Drilling a rotor *can* weaken it, that much is true. These *weak* spots are more prone to cracking, but because the rotor will stay cooler than a solid rotor would, less heat builds up and the chance of cracking the rotor is greatly reduced.

[rgaynor85]

yay smart talk lol

[IcemanSS]

I have done powerslot install's on a few cars. Have had no problems with them. I will use the powerslots on my own car when the time comes.

[BluMaj24]

I'm debating which route to take myself. Slotted, Slotted/Drilled, Drilled, or OEM. From what I've been reading...

Slotted - Allows gas to escape better than OEM, but wears pads down faster

Slotted/Drilled - Best braking and cooling. Risks include cracking, and faster brake pad wear.

Drilled - Allows better cooling of the rotor without wearing the pad down faster.

OEM - Most surface area, but least cooling ability. Normal pad wear.

Now I don't need anything too extravagent. My car is a daily driver that sees the track maybe once a month if that. Overall, I think my choice is a good quality drilled rotor. I'll take my risks with cracking, as it seems that is a less frequent occurence. I'd rather have long lasting pads with the holes to help cool...if they crack...I replace them and I warn others...if not...I'll be happy.

[Tru2Chevy]

Originally Posted by BluMaj24

My car is a daily driver that sees the track maybe once a month if that.

What sort of track? Strip, Road Course, or Auto-X?

If your car is mostly a daily driver, you should be perfectly fine with blank rotors, unless you just want the look of a slotted or drilled rotor.

- Justin

[qwikz28]

theres no written proof that slots or drilling allows better cooling. thats crap imo. its all about the quality and thickness of the rotor.

it also doesnt explain why Formula 1 cars and no-expense-spared race cars all use blanks.

[Tsar]

[JL8Jeff]

I don't think the slots or drilled holes are for cooling but rather to let the gases built up during hard braking escape which allows the pad to stay in better contact with the rotor for better stopping ability. Or, I just made all that up because it sounds good. Personally, I thought the dimpled rotors I had on my old 93 Z28 did help the car stop better in adverse conditions. Bigger calipers/pads/rotors will probably help it stop better but at what cost is it worth it? It all comes down to what you're comfortable with spending your money on.

[Tru2Chevy]

Originally Posted by JL8Jeff

I don't think the slots or drilled holes are for cooling but rather to let the gases built up during hard braking escape which allows the pad to stay in better contact with the rotor for better stopping ability.

Yes, that is what they are designed for. Most pads nowadays have a slot or two in them to help gases escape, plus pad technology has come so far that they probably don't produce as much of the gases anyway....

- Justin

[BonzoHansen]

Originally Posted by Tru2Chevy

Yes, that is what they are designed for. Most pads nowadays have a slot or two in them to help gases escape, plus pad technology has come so far that they probably don't produce as much of the gases anyway....

- Justin

That is my understanding.

[johnjzjz]

In motorcycle racing the holes are a weight reduction ( small ) carbon rotors are not drilled - FIA 1 type for the bikes but we never used them the duel disc front ends we use are way over the top in stoping anyway and they are real pricey for carbon -- but they are lighter and have no or almost no heat issue -- jz

[WildBillyT]

As told to me by a guy who ran the brake dyno at Raybestos (testing new pads), take this for what it's worth in that context:

Pad material makes the biggest difference. Bigger than surface area or rotor type. Warped rotors are a myth. The runout on a "warped" rotor comes from material transfer from the brake pad.

[BluMaj24]

I did a bad thing and "assumed" that the gas release was cooling - Instead it's just a transfer of gas. I meant to say what you said JL8Jeff.

[BonzoHansen]

Originally Posted by WildBillyT

As told to me by a guy who ran the brake dyno at Raybestos (testing new pads), take this for what it's worth in that context:

Pad material makes the biggest difference. Bigger than surface area or rotor type. Warped rotors are a myth. The runout on a "warped" rotor comes from material transfer from the brake pad.

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

[Tru2Chevy]

Originally Posted by BonzoHansen

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

Good reading....

- Justin

[Batman]

Originally Posted by JSPERFORMANCE

you people can try to rationalize your theories all you want but you cant argue with real world results... drilled and slotted rotors are more resistant to warpage and glazing without adversly affecting braking efficiency............ period. And if you havent owned a set of these rotors or at least even driven a car or truck with them there is no need for you to reply.. thanks

I have to agree, I went through 3 sets of stock and stock style rotors running 12's in a year, all due to warpage. I spent the big bucks on the Baer eradispeeds and 29,000 miles and 150+ track passes and they are barely worn at all, never fade even at the auto X and knocked about 25% off my stopping distances. While I agree for a street car they are overkill, now that I am running 120+ at the track I wouldn't take anything else. They have proven themselves to me.

[qwikz28]

Originally Posted by Batman

I have to agree, I went through 3 sets of stock and stock style rotors running 12's in a year, all due to warpage. I spent the big bucks on the Baer eradispeeds and 29,000 miles and 150+ track passes and they are barely worn at all, never fade even at the auto X and knocked about 25% off my stopping distances. While I agree for a street car they are overkill, now that I am running 120+ at the track I wouldn't take anything else. They have proven themselves to me.

now i will respond by saying your old rotors were crap and these are made by a reputable company

i had powerslots and i now have brembo blanks, hawk pads both times. neither setup has warped or faded on me once. i will say a quality rotor is a quality rotor in any instance. only difference is the pads on my powerslots only lasted 10k miles

btw- the hawk pads have the slot in them for gas to escape.

[Batman]

Actually I had brembo blanks also, I said stock and stock ctyle (menaing no cross drilled or slotted) they didn't warp but can't even hold a candle to Baer's I have now for performance and wore out pretty fast. Granted I had a more aggressive pad then I do now, I am running Hawks now

[qwikz28]

Originally Posted by Batman

Actually I had brembo blanks also, I said stock and stock ctyle (menaing no cross drilled or slotted) they didn't warp but can't even hold a candle to Baer's I have now for performance and wore out pretty fast. Granted I had a more aggressive pad then I do now, I am running Hawks now

i like the hawks i have. but they are the only pad i have run besides OEM. what else have you run before?

[johnjzjz]

high end drag car brakes do not come blank they only come with holes and the rotors are only 1/4 inch or .250 thick our super gas car 9 40 143 mph stops at island with plenty to spair and no shoot my friends car Gen 3 -maro - 8 40 167 mph also does not use his shoot and stops with the same type willwood brakes with no issue the first set of rotors lasted 8 years 600 passes ????? for me the holes work and thats from doing it at high speed with not only cars - jz