Thoughts On Crossdrilled/slotted Rotors Vs Plain
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now i know the weight difference between the drilled and slotted v.s. regular disc is minimal, but keep in mind, less rotational wieght at the wheel will allow the wheel to stop quicker.
also alot of those big brake kits have an aluminum (or some other lightwieght material) for the center (top hat) and a flat non-d/s friction area-... this allows the rotational wieght to be the same wieght as the stock rotor-... but with a larger friction surface.
KeWLKaT- did you ever have d/s rotors? i can't remember wether you stated that or not.
anyone wanna send it in to mythbusters?
also alot of those big brake kits have an aluminum (or some other lightwieght material) for the center (top hat) and a flat non-d/s friction area-... this allows the rotational wieght to be the same wieght as the stock rotor-... but with a larger friction surface.
KeWLKaT- did you ever have d/s rotors? i can't remember wether you stated that or not.
anyone wanna send it in to mythbusters?
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From: Ashland, KY
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I read an article on this in scc once. I think it was on their project miata. They explained that bbk with drill/slotted where often mistaken for being designed to stop the car quicker which isn't the case at all.
Drilled/Slotted is for FADE RESISTANCE. It is a cooling device keeping the rotors cooler keeps the braking more reliable. (however originally it was more about the gas thing read the wiki on disc brakes)
Now for normal drivers this isn't an issue but if you've ever made a lap around a track, country road, etc. you'll notice the difference. SCC did tests after upgrading and actually lost initially in stopping distance. But after getting a few 80-30 mph stops in the normal street brakes nearly doubled the performance brakes in stopping distance. It's all about consistency.
and btw, sure those porsche, ferrari, lamborghini's, etc are purchased by tons of people who don't know the difference between a cam shaft and a crank shaft but they are built for/by the people that do. Ferrari isn't going to do something to the car to hurt performance to increase "looks" so they can sell it to a couple more doctors.
Drilled/Slotted is for FADE RESISTANCE. It is a cooling device keeping the rotors cooler keeps the braking more reliable. (however originally it was more about the gas thing read the wiki on disc brakes)
Now for normal drivers this isn't an issue but if you've ever made a lap around a track, country road, etc. you'll notice the difference. SCC did tests after upgrading and actually lost initially in stopping distance. But after getting a few 80-30 mph stops in the normal street brakes nearly doubled the performance brakes in stopping distance. It's all about consistency.
and btw, sure those porsche, ferrari, lamborghini's, etc are purchased by tons of people who don't know the difference between a cam shaft and a crank shaft but they are built for/by the people that do. Ferrari isn't going to do something to the car to hurt performance to increase "looks" so they can sell it to a couple more doctors.
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From: Quebec, Canada
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Hey guys,
I admit I mistyped. I meant CARBON ROTORS = metal. They are not pure carbon, they are just alloys with high concentration of carbon in them. I am well aware that carbon is not a metal smile.gif
You guys advance good points too, but I have nothing more to add really. It comes down to personal choice.
Like I said (i dont remember if it was on this forum or not), I will probably get some DS rotors with my BBK for the look only, I don't care about performance as much anymore, and I just happen to have bigger calipers on hand at the moment. Right now I have OE replacement plain rotors which have never failed me, I'm just waiting for the next brake job (next 1-2 year).
I just wanted to give you guys out there some food for thought. I do, however, still maintain my point.
I admit I mistyped. I meant CARBON ROTORS = metal. They are not pure carbon, they are just alloys with high concentration of carbon in them. I am well aware that carbon is not a metal smile.gif
You guys advance good points too, but I have nothing more to add really. It comes down to personal choice.
Like I said (i dont remember if it was on this forum or not), I will probably get some DS rotors with my BBK for the look only, I don't care about performance as much anymore, and I just happen to have bigger calipers on hand at the moment. Right now I have OE replacement plain rotors which have never failed me, I'm just waiting for the next brake job (next 1-2 year).
I just wanted to give you guys out there some food for thought. I do, however, still maintain my point.
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From: Kingsland, GA
Dude, you make some good points, but the fact remains that you've been mislead about this. It's not about the stopping force, its for cooling. The holes and slots makes for a larger surface area for the entire rotor, not the friction surface. And I don't give a damn what some moron wrote on wikipedia, some brake pads still use asbestos. Manufacturers stopped it for a while, but then realized that there's really nothing wrong with using the material since mechanics no longer reline shoes and rivet new material to pads. I had a representative from Raybestos come and speak to our shop for a sales pitch, and I asked him about the asbestos thing, and he verified that it is still used, but in lower amounts. Take my advice, it's legitimate expert knowledge: Drilled and slotted rotors cool better, which make the brakes work better.
If you've ever driven in the mountains, you'd know to downshift when going downhill rather than ride your brake. Why? Because you'll OVERHEAT the pads, and then a layer of expanding gas will develop between your pad and rotor. According to Newton's laws of motion, it's going to push that piston back into the caliper because the rotor's not going to enjoy having a force acted upon it, and will push back with an equal and opposite reaction. Now, take a D/S rotor, and give those gasses somewhere to vent, and your rotor will cool down a hell of alot faster.
Ever smoked a clutch? What's all that white stuff in the air surrounding your car? I'll give you a hint, it's not a liquid or solid.... it's gas!!!!! It's the exact same gas that develops around your brake pads when they overheat.
And F1 cars use fully metallic brake pads, not semimetallic or organic. That means that no gasses will be emitted, so there's really no need for D/S there. Ever watched an F1 car at night? Their rotors glow red, sometimes yellow when braking in turns.
Edit: I didn't fully read tdonnell's post before I posted my info, but this does back up the validity about the metallic pads.
If you've ever driven in the mountains, you'd know to downshift when going downhill rather than ride your brake. Why? Because you'll OVERHEAT the pads, and then a layer of expanding gas will develop between your pad and rotor. According to Newton's laws of motion, it's going to push that piston back into the caliper because the rotor's not going to enjoy having a force acted upon it, and will push back with an equal and opposite reaction. Now, take a D/S rotor, and give those gasses somewhere to vent, and your rotor will cool down a hell of alot faster.
Ever smoked a clutch? What's all that white stuff in the air surrounding your car? I'll give you a hint, it's not a liquid or solid.... it's gas!!!!! It's the exact same gas that develops around your brake pads when they overheat.
And F1 cars use fully metallic brake pads, not semimetallic or organic. That means that no gasses will be emitted, so there's really no need for D/S there. Ever watched an F1 car at night? Their rotors glow red, sometimes yellow when braking in turns.
Edit: I didn't fully read tdonnell's post before I posted my info, but this does back up the validity about the metallic pads.
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From: Leesville, Louisiana
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QUOTE (KeWLKaT @ Jan 18 2008, 12:40 PM)
DTN::
How am I giving you opinions? You keep saying this: it helps for cooling. It helps for cooling. Where is your factual data? I gave you a result that DS rotors have around 2/3 of the mating surface between rotor and pad.
Listen. Do you have any racing experience? FYI I have been racing and building custom cars since 2 years now on cars made from scratch. We are one of the most top ranked teams worldwide between engineering universities, and that's because we get it right. And we have tried the crossdrilling thing before, but actual data we picked up back in my first season with them proved to us that they are crap.
How am I giving you opinions? You keep saying this: it helps for cooling. It helps for cooling. Where is your factual data? I gave you a result that DS rotors have around 2/3 of the mating surface between rotor and pad.
Listen. Do you have any racing experience? FYI I have been racing and building custom cars since 2 years now on cars made from scratch. We are one of the most top ranked teams worldwide between engineering universities, and that's because we get it right. And we have tried the crossdrilling thing before, but actual data we picked up back in my first season with them proved to us that they are crap.
I gave you figures from my infra red thermometer. here's some articals.
QUOTE ("wikipedia.org - heatsink")
The most common design of a heat sink is a metal device with many fins. The high thermal conductivity of the metal combined with its large surface area result in the rapid transfer of thermal energy to the surrounding, cooler, air. This cools the heat sink and whatever it is in direct thermal contact with. Use of fluids (for example coolants in refrigeration) and thermal interface material (in cooling electronic devices) ensures good transfer of thermal energy to the heat sink. Similarly a fan may improve the transfer of thermal energy from the heat sink to the air.
QUOTE ("wikipedia.org -disc brake")
The design of the disc varies somewhat. Some are simply solid cast iron, but others are hollowed out with fins joining together the disc's two contact surfaces (usually included as part of a casting process). This "ventilated" disc design helps to dissipate the generated heat and is commonly used on the more-heavily-loaded front discs. Many higher performance brakes have holes drilled through them. This is known as cross-drilling and was originally done in the 1960s on racing cars. Brake pads will outgas and under use may create boundary layer of gas between the pad and the disc hurting braking performance. Cross-drilling was created to provide the gas someplace to escape. Although modern brake pads seldom suffer from outgassing problems, water residue may build up after a vehicle passes through a puddle and impede braking performance. For this reason, and for heat dissipation purposes, Cross Drilling is still used on some braking components, but is not favored for racing or other hard use as the holes are a source of stress cracks under severe conditions.
Discs may also be slotted, where shallow channels are machined into the disc to aid in removing dust and gas. Slotting is the preferred method in most racing environments to remove gas, water, and de-glaze brake pads. Some discs are both drilled and slotted. Slotted discs are generally not used on standard vehicles because they quickly wear down brake pads; however, this removal of material is beneficial to race vehicles since it keeps the pads soft and avoids vitrification of their surfaces.
A Mountain Bike Disc brake On the road, drilled or slotted discs still have a positive effect in wet conditions because the holes or slots prevent a film of water building up between the disc and the pads. Cross drilled discs will eventually crack at the holes due to metal fatigue. Cross-drilled brakes that are manufactured poorly or subjected to high stresses will crack much sooner and more severely.
Discs may also be slotted, where shallow channels are machined into the disc to aid in removing dust and gas. Slotting is the preferred method in most racing environments to remove gas, water, and de-glaze brake pads. Some discs are both drilled and slotted. Slotted discs are generally not used on standard vehicles because they quickly wear down brake pads; however, this removal of material is beneficial to race vehicles since it keeps the pads soft and avoids vitrification of their surfaces.
A Mountain Bike Disc brake On the road, drilled or slotted discs still have a positive effect in wet conditions because the holes or slots prevent a film of water building up between the disc and the pads. Cross drilled discs will eventually crack at the holes due to metal fatigue. Cross-drilled brakes that are manufactured poorly or subjected to high stresses will crack much sooner and more severely.QUOTE ("wikipedia.org - brake fade")
Brake modification to reduce fade
High performance brake components provide enhanced stopping power by improving friction while reducing brake fade. Improved friction is provided by lining materials that have a higher coefficient of friction than stock brake pads while brake fade is reduced through the use of more expensive binding resins with a higher melting point along with slotted, drilled, or dimpled rotors that reduce the gaseous boundary layer in addition to providing enhanced heat dissipation. Heat buildup in brakes can be further addressed by body modifications that direct cold air to the brakes.
Both disc and drum brakes can be improved by any technique that removes heat from the braking surfaces.
Drum brake fade can be reduced and overall performance enhanced somewhat by an old "hot rodder" technique of drum drilling. A carefully chosen pattern of holes is drilled through the drum working section; drum rotation centrifugally pumps a small amount air through the shoe to drum gap, removing heat; fade caused by water-wet brakes is reduced since the water is centrifugally driven out; and some brake-material dust exits the holes. Brake drum drilling requires careful detailed knowledge of brake drum physics and is an advanced technique probably best left to professionals. There are performance-brake shops that will make the necessary modifications safely. The Bugatti Veyron for example has turbine cooled brakes that reduce fade to almost nothing considering the speeds it is braking from.
High performance brake components provide enhanced stopping power by improving friction while reducing brake fade. Improved friction is provided by lining materials that have a higher coefficient of friction than stock brake pads while brake fade is reduced through the use of more expensive binding resins with a higher melting point along with slotted, drilled, or dimpled rotors that reduce the gaseous boundary layer in addition to providing enhanced heat dissipation. Heat buildup in brakes can be further addressed by body modifications that direct cold air to the brakes.
Both disc and drum brakes can be improved by any technique that removes heat from the braking surfaces.
Drum brake fade can be reduced and overall performance enhanced somewhat by an old "hot rodder" technique of drum drilling. A carefully chosen pattern of holes is drilled through the drum working section; drum rotation centrifugally pumps a small amount air through the shoe to drum gap, removing heat; fade caused by water-wet brakes is reduced since the water is centrifugally driven out; and some brake-material dust exits the holes. Brake drum drilling requires careful detailed knowledge of brake drum physics and is an advanced technique probably best left to professionals. There are performance-brake shops that will make the necessary modifications safely. The Bugatti Veyron for example has turbine cooled brakes that reduce fade to almost nothing considering the speeds it is braking from.
You can also look up what causes warping, and scarring and figure out for yourself that there is nothing but benefeits for daily drivers from a high quality Drilled and Slotted brake kit.
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I thought they used fully metallic pads! I just didn't want to sound like an ass if I was wrong, lol.
I was also going to state the glowing red rotors, metallic pads acutally work better when they get that hot, if I am correct. Otherwise those cars would be fading into a wall cool.gif .
I was also going to state the glowing red rotors, metallic pads acutally work better when they get that hot, if I am correct. Otherwise those cars would be fading into a wall cool.gif .
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From: Quebec, Canada
Vehicle: Elantra XD GT
Well anyone serious about braking force is going to use ceramic pads anyways. So the gas theory is just way too out there.
Don't tell me I have been mislead. You guys are missing this point:
It doesn't DRAMATICALLY increase the surface of friction. Why?
Here's why (bear with me or I'll make a picture): By removing the material of an X diameter in the rotor, you are creating the new surface of contact representing the outer area of the drilled cylinder, which depends on the thickness of the half with the drill. However, you are completely removing the diameter area. Slots, however, do increase the area without losing any.
If you look at EBC dimpled rotors, IMO, they are the best compromise.
DTN:::
What I was referring to is the way in which you measured it. It makes no sense whatsoever, taking 2 totally different data measured completely differently and at completely different intervals. I know what thermal properties are, probably more than most here, as I study this stuff daily. It's just that you guys aren't able to grasp the full picture.
Don't tell me I have been mislead. You guys are missing this point:
It doesn't DRAMATICALLY increase the surface of friction. Why?
Here's why (bear with me or I'll make a picture): By removing the material of an X diameter in the rotor, you are creating the new surface of contact representing the outer area of the drilled cylinder, which depends on the thickness of the half with the drill. However, you are completely removing the diameter area. Slots, however, do increase the area without losing any.
If you look at EBC dimpled rotors, IMO, they are the best compromise.
DTN:::
What I was referring to is the way in which you measured it. It makes no sense whatsoever, taking 2 totally different data measured completely differently and at completely different intervals. I know what thermal properties are, probably more than most here, as I study this stuff daily. It's just that you guys aren't able to grasp the full picture.
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From: Columbus, Ohio
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QUOTE (KeWLKaT @ Jan 19 2008, 02:13 PM)
Well anyone serious about braking force is going to use ceramic pads anyways. So the gas theory is just way too out there.
Don't tell me I have been mislead. You guys are missing this point:
It doesn't DRAMATICALLY increase the surface of friction. Why?
Don't tell me I have been mislead. You guys are missing this point:
It doesn't DRAMATICALLY increase the surface of friction. Why?
have you ever even had D/S rotors on your car? you did not mention.
because it does DRAMATICALLY change the stoping power, everyone who has a set has allready said it was noticable diffrence. you keep trying to tell us how OUR OWN BRAKES FEEL, and all of us has allready told you its diffrence? what more do you want??