Posted: 11/21/2015 12:00:59 AM EDT
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It's been said that cross drilled rotors are bad to run on the street, but why is it that companies like Mercedes Benz and Porsche run them on the majority of cars sold?
Are slotted rotors better than cross drilled? Are either better than just regular rotors? |
| Drilled and slotted increases surface area to promote cooling. It does so at the detriment of stopping area. If you are not getting any "brake fade" due to over heating brakes, then there is no reason to go drilled and slotted. Most, if not all, street cars have no issues with brake fade so no need for drilled and slotted. |
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Drilled rotors do have more surface area, but they also have less mass, which lowers the overall heat capacity. Drilled rotors are aesthetically pleasing, that's why companies include them on sports cars.
I've been using them for about 10 years and have never had any cracks or other issues. 
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| Cross drilled for street use are an over kill......for a street car that's tracked the could serve a purpose......stay away from cheap non-name brand cross drilled rotors....I have seen them have catastrophic failure more than once...when used for road racing . |
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Dont the holes actually decrease surface area?
AFAIK those holes are for getting gas out from between pads and rotors that really doesnt happen anymore with modern materials. Any advantages and disadvantage won't really manifest in street driving IMO. I doubt these do anything an equivalent blank rotor would not do on a street car. |
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Quoted:
Dont the holes actually decrease surface area? AFAIK those holes are for getting gas out from between pads and rotors that really doesnt happen anymore with modern materials. Any advantages and disadvantage won't really manifest in street driving IMO. I doubt these do anything an equivalent blank rotor would not do on a street car. Contact area is decreased. Surface area is increased, much like fluting on a rifle barrel, which aids in cooling. |
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Quoted: Contact area is decreased. Surface area is increased, much like fluting on a rifle barrel, which aids in cooling. Quoted: Quoted: Dont the holes actually decrease surface area? AFAIK those holes are for getting gas out from between pads and rotors that really doesnt happen anymore with modern materials. Any advantages and disadvantage won't really manifest in street driving IMO. I doubt these do anything an equivalent blank rotor would not do on a street car. Contact area is decreased. Surface area is increased, much like fluting on a rifle barrel, which aids in cooling. It's probably just as useless as well... |
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Quoted:
Dont the holes actually decrease surface area? AFAIK those holes are for getting gas out from between pads and rotors that really doesnt happen anymore with modern materials. Any advantages and disadvantage won't really manifest in street driving IMO. I doubt these do anything an equivalent blank rotor would not do on a street car. No, the surface area is increased by the circumference of the holes x the thickness of the rotor - the diameter of the hole. What is decreased is the heat capacity of the rotor since it has less mass. Modern pads don't off gas as much but they do transfer heat to the caliper and then the brake fluid. This will also cause brake fade when fluid boils, usually around 300-500 degree F depending on your fluid type and how often you change it. This is why performance cars will also have slots on the back of the caliper like in my picture above. |
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Quoted: It's been said that cross drilled rotors are bad to run on the street, but why is it that companies like Mercedes Benz and Porsche run them on the majority of cars sold? Are slotted rotors better than cross drilled? Are either better than just regular rotors? |
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I've got factory OE drilled on one vehicle, and OE solid rotors on another vehicle. Honestly, the best performing is the always the one I've had the most recent brake system flush done on. (yes, I pay the stealership to do the BG flush - I just don't have the time to mess with it myself) |
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What the hell are people doing driving on the street in a manner that overloads the stock brakes?!?!
When I had my C3500 dually, I had to replace the front rotors. Each one was a huge chunk of steel, easily 60lb. I challenge you to find a higher performance street vehicle brake system than a truck with a 10,000lb GVWR and a rated towing capacity of 13,5000lb. Sports cars are cute little toys with the payload capacity of my daughter's backpack and are designed to be light. The biggest problems are the lightweight components warping or cracking from the heat. Race cars have CONSUMABLES that are almost lifetime items on a street car. I went through a set of pads about every third weekend and a set of rotors every year on the road race bike. I think I have only ever put ONE set of rotors and pads on each car I've owned, and the highest mileage car for me was the 230,000 miles I put on my 300sd. The C3500 got 60,000 miles before I sold it. My current ride is 50,000 miles into the brakes I put on it when I got the car. It gets daily and sometimes max payload use (99 Mercedes e320 wagon). I don't baby my vehicles. So let's all be clear. Drilled/slotted rotors are there to look cool, or make up for some really unsafe (street) driving habits. |
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Quoted: What the hell are people doing driving on the street in a manner that overloads the stock brakes?!?! When I had my C3500 dually, I had to replace the front rotors. Each one was a huge chunk of steel, easily 60lb. I challenge you to find a higher performance street vehicle brake system than a truck with a 10,000lb GVWR and a rated towing capacity of 13,5000lb. Sports cars are cute little toys with the payload capacity of my daughter's backpack and are designed to be light. The biggest problems are the lightweight components warping or cracking from the heat. Race cars have CONSUMABLES that are almost lifetime items on a street car. I went through a set of pads about every third weekend and a set of rotors every year on the road race bike. I think I have only ever put ONE set of rotors and pads on each car I've owned, and the highest mileage car for me was the 230,000 miles I put on my 300sd. The C3500 got 60,000 miles before I sold it. My current ride is 50,000 miles into the brakes I put on it when I got the car. It gets daily and sometimes max payload use (99 Mercedes e320 wagon). I don't baby my vehicles. So let's all be clear. Drilled/slotted rotors are there to look cool, or make up for some really unsafe (street) driving habits. |