gts rotors
09-10-2012, 10:08 PM
#61
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Some very interesting stuff, science fact, about what is happening;
The amount of traction which can be obtained for an auto tire is determined by the coefficient of static friction between the tire and the road. Static friction is the amount of friction between two surfaces when they are not slipping, like a tire and the road under normal circumstances. If the wheel is locked and sliding, the force of friction is determined by the coefficient of kinetic friction and is usually significantly less. Anytime you lock brakes it takes longer to stop. Assuming that a wheel is rolling without slipping, the surface friction does no work against the motion of the wheel and no energy is lost at that point.
Now, how does it apply to ABS and car tires? Keep in mind that as a car tire rolls, there is a patch of rubber that is actually stationary and static friction is in effect. We want to maintain this static friction for as long as possible (for grip, traction, and control). If the rubber starts to slide across the asphalt (when the wheel locks up), we lose the benefit of the static friction force and the stopping force exerted by the tires on the car. ABS reduces the brake pressure allowing the wheel to turn thereby continuing to slow it at the maximum possible rate
Factors Affecting The Coefficient of Friction;
The main factors affecting the friction coefficient are road surface texture and condition and tire composition.Condition of the roadway refers to the presence of snow, ice, sand and other lubricants. The presence of any of these will make the surface more slippery, which reduces the coefficient of friction.
Texture of the road surface refers to the natural roughness of the asphalt. A relatively new asphalt roadway has a "sharper" surface with a high coefficient of friction. An older well-travelled asphalt roadway has a smoother, slicker surface with a lower coefficient of friction.
Tire composition and wear surprisingly plays a lesser role in determining the coefficient. It appears as though road surface texture and condition are the more important factors.
Jones and Childers report coefficients of friction of about 0.7 for dry roads and 0.4 for wet roads. The tread design represents an "all weather" compromise. If you were an Indianapolis race driver, you would use "slick" racing tires with no tread. On dry surfaces you might get as high as 0.9 as a coefficient of friction, but driving them on wet roads would be dangerous since the wet road coefficient might be as low as 0.1 .
Rubber Dry Asphalt 0.9 (0.5 - 0.8)1)
Rubber Wet Asphalt 0.25 - 0.751)
Rubber Dry Concrete 0.6 - 0.851)
Rubber Wet Concrete 0.45 - 0.751)
Tire shape;
People who say wider tires make more grip because ;''there is more rubber on the road' are wrong. They are both wrong that it makes mroe grip and that there is more rubber on the road.
When you make a tire wider, you alter the contact patch to be wider , but it reduces in length. So depending on sidewall stiffness, a wider tire can actually give less rubber on the road.
Wider, low sidewall tires will cool better than narrow tall tires.Back to contact patch, you can safely assume that contact patch stays roughly the same area with wide or narrow tires (as long as the load stsys the same).A wide tire will generate more lateral force per slip angle making cornering better. F1 cars DO NOT have wide tires for linear acceleration.As we know a wider contact patch gives better cornering performance, a narrow but long contact patch is what you want for linear acceleration. The F1 patch will be wider and shorter for good cornering, the drag patch will be longer and narrower (relatively) for good linear acceleration.Wider contact patch sacrifices linear traction for lateral, narrow tyres sacrifices lateral for longditudinal traction. And the most important thing about tyres is not contact patch area but that they are correct working temperature.
A wider tyre does not give more grip, but it allows you to use softer rubber without reducing the lifespan of the tyre. It's the softer rubber that gives you more grip.
the amount of frictional force is proportional to the surface area of contact, but it is also proportional to the pressure with which the two surfaces are "pressed" together.
If you increase the surface area however, you will by definition decrease the pressure since pressure is "weight divided by surface area." So a change in surface area will cause two counterbalancing effects that leave, as you said, only the weight of the object to be considered.
Back to the real world: as you said, larger tires are used in order that softer material can be utilized. The greatest force required from the tires occurs during cornering. If a certain force were required to make a turn at high speeds with thin tires, the material itself could fail (similar to the fact that a rubber band will snap). You can see that this happens in racing when you get a close look at the old tires at they are replaced: small chunks are often ripped out.
This failure is not a failure of the frictional force; rather, it is a "stress" related failure of the material. Wider tires will reduce the stress per unit area of each tire.
The bottom line is this-- BRAKES STOP CARS, not tires. Some tires are better than others and allow the brakes to do a better job. Getting tires too hot will reduce static friction, leading to slip. More efficient brakes, ones that dissipate heat faster, will stop any car better than less efficient brakes. Wider tires are better for cornering, less efficient for stopping and going.
From F1;
In physical terms we can state that energy is the capacity of a physical system to do work. When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat.
Formula One cars must sometimes decelerate in a matter of seconds from 350 km/h to about 70 km/h. During such heavy braking, the temperature of the brake rotor and pads can warm up from 400°C to more than 1000°C.
At 100 km/h, these values are just as mind-blowing 1.4 seconds and 17 meters! Under these heavy braking periods, a driver is subjected to a horizontal deceleration of close to 5.4G.
the disk/caliper tandem operating temperature increases by 100°C per tenth of a second for the first half-second of braking
http://www.youtube.com/watch?v=JMp7UR_YGsw
The amount of traction which can be obtained for an auto tire is determined by the coefficient of static friction between the tire and the road. Static friction is the amount of friction between two surfaces when they are not slipping, like a tire and the road under normal circumstances. If the wheel is locked and sliding, the force of friction is determined by the coefficient of kinetic friction and is usually significantly less. Anytime you lock brakes it takes longer to stop. Assuming that a wheel is rolling without slipping, the surface friction does no work against the motion of the wheel and no energy is lost at that point.
Now, how does it apply to ABS and car tires? Keep in mind that as a car tire rolls, there is a patch of rubber that is actually stationary and static friction is in effect. We want to maintain this static friction for as long as possible (for grip, traction, and control). If the rubber starts to slide across the asphalt (when the wheel locks up), we lose the benefit of the static friction force and the stopping force exerted by the tires on the car. ABS reduces the brake pressure allowing the wheel to turn thereby continuing to slow it at the maximum possible rate
Factors Affecting The Coefficient of Friction;
The main factors affecting the friction coefficient are road surface texture and condition and tire composition.Condition of the roadway refers to the presence of snow, ice, sand and other lubricants. The presence of any of these will make the surface more slippery, which reduces the coefficient of friction.
Texture of the road surface refers to the natural roughness of the asphalt. A relatively new asphalt roadway has a "sharper" surface with a high coefficient of friction. An older well-travelled asphalt roadway has a smoother, slicker surface with a lower coefficient of friction.
Tire composition and wear surprisingly plays a lesser role in determining the coefficient. It appears as though road surface texture and condition are the more important factors.
Jones and Childers report coefficients of friction of about 0.7 for dry roads and 0.4 for wet roads. The tread design represents an "all weather" compromise. If you were an Indianapolis race driver, you would use "slick" racing tires with no tread. On dry surfaces you might get as high as 0.9 as a coefficient of friction, but driving them on wet roads would be dangerous since the wet road coefficient might be as low as 0.1 .
Rubber Dry Asphalt 0.9 (0.5 - 0.8)1)
Rubber Wet Asphalt 0.25 - 0.751)
Rubber Dry Concrete 0.6 - 0.851)
Rubber Wet Concrete 0.45 - 0.751)
Tire shape;
People who say wider tires make more grip because ;''there is more rubber on the road' are wrong. They are both wrong that it makes mroe grip and that there is more rubber on the road.
When you make a tire wider, you alter the contact patch to be wider , but it reduces in length. So depending on sidewall stiffness, a wider tire can actually give less rubber on the road.
Wider, low sidewall tires will cool better than narrow tall tires.Back to contact patch, you can safely assume that contact patch stays roughly the same area with wide or narrow tires (as long as the load stsys the same).A wide tire will generate more lateral force per slip angle making cornering better. F1 cars DO NOT have wide tires for linear acceleration.As we know a wider contact patch gives better cornering performance, a narrow but long contact patch is what you want for linear acceleration. The F1 patch will be wider and shorter for good cornering, the drag patch will be longer and narrower (relatively) for good linear acceleration.Wider contact patch sacrifices linear traction for lateral, narrow tyres sacrifices lateral for longditudinal traction. And the most important thing about tyres is not contact patch area but that they are correct working temperature.
A wider tyre does not give more grip, but it allows you to use softer rubber without reducing the lifespan of the tyre. It's the softer rubber that gives you more grip.
the amount of frictional force is proportional to the surface area of contact, but it is also proportional to the pressure with which the two surfaces are "pressed" together.
If you increase the surface area however, you will by definition decrease the pressure since pressure is "weight divided by surface area." So a change in surface area will cause two counterbalancing effects that leave, as you said, only the weight of the object to be considered.
Back to the real world: as you said, larger tires are used in order that softer material can be utilized. The greatest force required from the tires occurs during cornering. If a certain force were required to make a turn at high speeds with thin tires, the material itself could fail (similar to the fact that a rubber band will snap). You can see that this happens in racing when you get a close look at the old tires at they are replaced: small chunks are often ripped out.
This failure is not a failure of the frictional force; rather, it is a "stress" related failure of the material. Wider tires will reduce the stress per unit area of each tire.
The bottom line is this-- BRAKES STOP CARS, not tires. Some tires are better than others and allow the brakes to do a better job. Getting tires too hot will reduce static friction, leading to slip. More efficient brakes, ones that dissipate heat faster, will stop any car better than less efficient brakes. Wider tires are better for cornering, less efficient for stopping and going.
From F1;
In physical terms we can state that energy is the capacity of a physical system to do work. When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat.
Formula One cars must sometimes decelerate in a matter of seconds from 350 km/h to about 70 km/h. During such heavy braking, the temperature of the brake rotor and pads can warm up from 400°C to more than 1000°C.
At 100 km/h, these values are just as mind-blowing 1.4 seconds and 17 meters! Under these heavy braking periods, a driver is subjected to a horizontal deceleration of close to 5.4G.
the disk/caliper tandem operating temperature increases by 100°C per tenth of a second for the first half-second of braking
http://www.youtube.com/watch?v=JMp7UR_YGsw
first of all, start doing some research on stopping and cornering and the racing tire. slip angle, and percentage are both distance cousins and talk about optimal rubber distortion to maximize cornering and acceleration or deceleration. absolutely , wider tires can stop faster, just as they can accelerate faster . (ask any drag racer this) the occilating slip% of a dragster is just like ABS on decel.
again, brake size and cooling capacity have only to do with making brakes work at tempurature. intil they are heat soaked and beyond their limit, they all pretty much work the same (all racing brakes of certain size range, not old drum, or RX7 hockey puck brake pads. (or OB 928s
)ABS works by keeping the tires just at the limit of slip % to optimize stoping power of the brake system. without the tires, you have no braking. again, think racing slicks in the rain. you dont need a lot of force to equal the capability of the TIRE to slow the car down. the tire determins the stopping , no the braking system, though very important. (just as an engine is important to acceleration, but limited by the tires as well. you get wheel spin,you lose acceleration. just the right amount of slip, and you maximize the hp applied the road. this is limited and progressive up until you hit power and it doesnt exceed the grip or slip %.
again, big brakes, and then bigger brakes ONLY effect how the car will stop after a few laps, not one lap.
again, your comparison of the porsches with different brakes from 2004 to 2007 is a good one!! this proves you are NOT lookinig at the real factors of why the cars stop at differnet distances from 60mph. again, it has to do with setup, weight distribution, suspension, track width, roll centers and height, which determine the weight transfer which is result of those factors. if they change in the cars dimensions, the braking effectiveness changes. i.e. 997 vs 996 GT3s are different in areas of this. tire size, quality, drive, conditions, weight distribution, ride heigh and roll centers, as welll as several other factors that will change stopping distance having nothing to do with rotor size or pad quality. (assuming both are racing pads) 60 to 0mph is a mild test of braking. well within the max capability of any modern braking system, after a few turns at laguna, the differences will be seen , and thats the point of this.
street cars dont push brakes , racing does! (and if your street set up is not up to your task, put on some racing brake pads and that should solve the issue)
remember that race i reported back from?? one of the evo lancers was cooking and boiling fluid??? he had brembo big reds, 13 " rotors. basically more than i had ....... his lap times were 4 seconds slower......... i had no issues....... same tires., same pagid orange race pads....same weight of car, same hp...... same day..... same track.......... hmmmmmmmm
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
and the best thing is you proved to all of us u don't need 150,000 worth of equipment to win
09-10-2012, 10:16 PM
#62
Rennlist Member
Some very interesting stuff, science fact, about what is happening;
The amount of traction which can be obtained for an auto tire is determined by the coefficient of static friction between the tire and the road. Static friction is the amount of friction between two surfaces when they are not slipping, like a tire and the road under normal circumstances. If the wheel is locked and sliding, the force of friction is determined by the coefficient of kinetic friction and is usually significantly less. Anytime you lock brakes it takes longer to stop. Assuming that a wheel is rolling without slipping, the surface friction does no work against the motion of the wheel and no energy is lost at that point.
Now, how does it apply to ABS and car tires? Keep in mind that as a car tire rolls, there is a patch of rubber that is actually stationary and static friction is in effect. We want to maintain this static friction for as long as possible (for grip, traction, and control). If the rubber starts to slide across the asphalt (when the wheel locks up), we lose the benefit of the static friction force and the stopping force exerted by the tires on the car. ABS reduces the brake pressure allowing the wheel to turn thereby continuing to slow it at the maximum possible rate
Factors Affecting The Coefficient of Friction;
The main factors affecting the friction coefficient are road surface texture and condition and tire composition.Condition of the roadway refers to the presence of snow, ice, sand and other lubricants. The presence of any of these will make the surface more slippery, which reduces the coefficient of friction.
Texture of the road surface refers to the natural roughness of the asphalt. A relatively new asphalt roadway has a "sharper" surface with a high coefficient of friction. An older well-travelled asphalt roadway has a smoother, slicker surface with a lower coefficient of friction.
Tire composition and wear surprisingly plays a lesser role in determining the coefficient. It appears as though road surface texture and condition are the more important factors.
Jones and Childers report coefficients of friction of about 0.7 for dry roads and 0.4 for wet roads. The tread design represents an "all weather" compromise. If you were an Indianapolis race driver, you would use "slick" racing tires with no tread. On dry surfaces you might get as high as 0.9 as a coefficient of friction, but driving them on wet roads would be dangerous since the wet road coefficient might be as low as 0.1 .
Rubber Dry Asphalt 0.9 (0.5 - 0.8)1)
Rubber Wet Asphalt 0.25 - 0.751)
Rubber Dry Concrete 0.6 - 0.851)
Rubber Wet Concrete 0.45 - 0.751)
Tire shape;
People who say wider tires make more grip because ;''there is more rubber on the road' are wrong. They are both wrong that it makes mroe grip and that there is more rubber on the road.
When you make a tire wider, you alter the contact patch to be wider , but it reduces in length. So depending on sidewall stiffness, a wider tire can actually give less rubber on the road.
Wider, low sidewall tires will cool better than narrow tall tires.Back to contact patch, you can safely assume that contact patch stays roughly the same area with wide or narrow tires (as long as the load stsys the same).A wide tire will generate more lateral force per slip angle making cornering better. F1 cars DO NOT have wide tires for linear acceleration.As we know a wider contact patch gives better cornering performance, a narrow but long contact patch is what you want for linear acceleration. The F1 patch will be wider and shorter for good cornering, the drag patch will be longer and narrower (relatively) for good linear acceleration.Wider contact patch sacrifices linear traction for lateral, narrow tyres sacrifices lateral for longditudinal traction. And the most important thing about tyres is not contact patch area but that they are correct working temperature.
A wider tyre does not give more grip, but it allows you to use softer rubber without reducing the lifespan of the tyre. It's the softer rubber that gives you more grip.
the amount of frictional force is proportional to the surface area of contact, but it is also proportional to the pressure with which the two surfaces are "pressed" together.
If you increase the surface area however, you will by definition decrease the pressure since pressure is "weight divided by surface area." So a change in surface area will cause two counterbalancing effects that leave, as you said, only the weight of the object to be considered.
Back to the real world: as you said, larger tires are used in order that softer material can be utilized. The greatest force required from the tires occurs during cornering. If a certain force were required to make a turn at high speeds with thin tires, the material itself could fail (similar to the fact that a rubber band will snap). You can see that this happens in racing when you get a close look at the old tires at they are replaced: small chunks are often ripped out.
This failure is not a failure of the frictional force; rather, it is a "stress" related failure of the material. Wider tires will reduce the stress per unit area of each tire.
The bottom line is this-- BRAKES STOP CARS, not tires. Some tires are better than others and allow the brakes to do a better job. Getting tires too hot will reduce static friction, leading to slip. More efficient brakes, ones that dissipate heat faster, will stop any car better than less efficient brakes. Wider tires are better for cornering, less efficient for stopping and going.
From F1;
In physical terms we can state that energy is the capacity of a physical system to do work. When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat.
Formula One cars must sometimes decelerate in a matter of seconds from 350 km/h to about 70 km/h. During such heavy braking, the temperature of the brake rotor and pads can warm up from 400°C to more than 1000°C.
At 100 km/h, these values are just as mind-blowing 1.4 seconds and 17 meters! Under these heavy braking periods, a driver is subjected to a horizontal deceleration of close to 5.4G.
the disk/caliper tandem operating temperature increases by 100°C per tenth of a second for the first half-second of braking
http://www.youtube.com/watch?v=JMp7UR_YGsw
The amount of traction which can be obtained for an auto tire is determined by the coefficient of static friction between the tire and the road. Static friction is the amount of friction between two surfaces when they are not slipping, like a tire and the road under normal circumstances. If the wheel is locked and sliding, the force of friction is determined by the coefficient of kinetic friction and is usually significantly less. Anytime you lock brakes it takes longer to stop. Assuming that a wheel is rolling without slipping, the surface friction does no work against the motion of the wheel and no energy is lost at that point.
Now, how does it apply to ABS and car tires? Keep in mind that as a car tire rolls, there is a patch of rubber that is actually stationary and static friction is in effect. We want to maintain this static friction for as long as possible (for grip, traction, and control). If the rubber starts to slide across the asphalt (when the wheel locks up), we lose the benefit of the static friction force and the stopping force exerted by the tires on the car. ABS reduces the brake pressure allowing the wheel to turn thereby continuing to slow it at the maximum possible rate
Factors Affecting The Coefficient of Friction;
The main factors affecting the friction coefficient are road surface texture and condition and tire composition.Condition of the roadway refers to the presence of snow, ice, sand and other lubricants. The presence of any of these will make the surface more slippery, which reduces the coefficient of friction.
Texture of the road surface refers to the natural roughness of the asphalt. A relatively new asphalt roadway has a "sharper" surface with a high coefficient of friction. An older well-travelled asphalt roadway has a smoother, slicker surface with a lower coefficient of friction.
Tire composition and wear surprisingly plays a lesser role in determining the coefficient. It appears as though road surface texture and condition are the more important factors.
Jones and Childers report coefficients of friction of about 0.7 for dry roads and 0.4 for wet roads. The tread design represents an "all weather" compromise. If you were an Indianapolis race driver, you would use "slick" racing tires with no tread. On dry surfaces you might get as high as 0.9 as a coefficient of friction, but driving them on wet roads would be dangerous since the wet road coefficient might be as low as 0.1 .
Rubber Dry Asphalt 0.9 (0.5 - 0.8)1)
Rubber Wet Asphalt 0.25 - 0.751)
Rubber Dry Concrete 0.6 - 0.851)
Rubber Wet Concrete 0.45 - 0.751)
Tire shape;
People who say wider tires make more grip because ;''there is more rubber on the road' are wrong. They are both wrong that it makes mroe grip and that there is more rubber on the road.
When you make a tire wider, you alter the contact patch to be wider , but it reduces in length. So depending on sidewall stiffness, a wider tire can actually give less rubber on the road.
Wider, low sidewall tires will cool better than narrow tall tires.Back to contact patch, you can safely assume that contact patch stays roughly the same area with wide or narrow tires (as long as the load stsys the same).A wide tire will generate more lateral force per slip angle making cornering better. F1 cars DO NOT have wide tires for linear acceleration.As we know a wider contact patch gives better cornering performance, a narrow but long contact patch is what you want for linear acceleration. The F1 patch will be wider and shorter for good cornering, the drag patch will be longer and narrower (relatively) for good linear acceleration.Wider contact patch sacrifices linear traction for lateral, narrow tyres sacrifices lateral for longditudinal traction. And the most important thing about tyres is not contact patch area but that they are correct working temperature.
A wider tyre does not give more grip, but it allows you to use softer rubber without reducing the lifespan of the tyre. It's the softer rubber that gives you more grip.
the amount of frictional force is proportional to the surface area of contact, but it is also proportional to the pressure with which the two surfaces are "pressed" together.
If you increase the surface area however, you will by definition decrease the pressure since pressure is "weight divided by surface area." So a change in surface area will cause two counterbalancing effects that leave, as you said, only the weight of the object to be considered.
Back to the real world: as you said, larger tires are used in order that softer material can be utilized. The greatest force required from the tires occurs during cornering. If a certain force were required to make a turn at high speeds with thin tires, the material itself could fail (similar to the fact that a rubber band will snap). You can see that this happens in racing when you get a close look at the old tires at they are replaced: small chunks are often ripped out.
This failure is not a failure of the frictional force; rather, it is a "stress" related failure of the material. Wider tires will reduce the stress per unit area of each tire.
The bottom line is this-- BRAKES STOP CARS, not tires. Some tires are better than others and allow the brakes to do a better job. Getting tires too hot will reduce static friction, leading to slip. More efficient brakes, ones that dissipate heat faster, will stop any car better than less efficient brakes. Wider tires are better for cornering, less efficient for stopping and going.
From F1;
In physical terms we can state that energy is the capacity of a physical system to do work. When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat.
Formula One cars must sometimes decelerate in a matter of seconds from 350 km/h to about 70 km/h. During such heavy braking, the temperature of the brake rotor and pads can warm up from 400°C to more than 1000°C.
At 100 km/h, these values are just as mind-blowing 1.4 seconds and 17 meters! Under these heavy braking periods, a driver is subjected to a horizontal deceleration of close to 5.4G.
the disk/caliper tandem operating temperature increases by 100°C per tenth of a second for the first half-second of braking
http://www.youtube.com/watch?v=JMp7UR_YGsw
first of all, start doing some research on stopping and cornering and the racing tire. slip angle, and percentage are both distance cousins and talk about optimal rubber distortion to maximize cornering and acceleration or deceleration. absolutely , wider tires can stop faster, just as they can accelerate faster . (ask any drag racer this) the occilating slip% of a dragster is just like ABS on decel.
again, brake size and cooling capacity have only to do with making brakes work at tempurature. intil they are heat soaked and beyond their limit, they all pretty much work the same (all racing brakes of certain size range, not old drum, or RX7 hockey puck brake pads. (or OB 928s
)ABS works by keeping the tires just at the limit of slip % to optimize stoping power of the brake system. without the tires, you have no braking. again, think racing slicks in the rain. you dont need a lot of force to equal the capability of the TIRE to slow the car down. the tire determins the stopping , no the braking system, though very important. (just as an engine is important to acceleration, but limited by the tires as well. you get wheel spin,you lose acceleration. just the right amount of slip, and you maximize the hp applied the road. this is limited and progressive up until you hit power and it doesnt exceed the grip or slip %.
again, big brakes, and then bigger brakes ONLY effect how the car will stop after a few laps, not one lap.
again, your comparison of the porsches with different brakes from 2004 to 2007 is a good one!! this proves you are NOT lookinig at the real factors of why the cars stop at differnet distances from 60mph. again, it has to do with setup, weight distribution, suspension, track width, roll centers and height, which determine the weight transfer which is result of those factors. if they change in the cars dimensions, the braking effectiveness changes. i.e. 997 vs 996 GT3s are different in areas of this. tire size, quality, drive, conditions, weight distribution, ride heigh and roll centers, as welll as several other factors that will change stopping distance having nothing to do with rotor size or pad quality. (assuming both are racing pads) 60 to 0mph is a mild test of braking. well within the max capability of any modern braking system, after a few turns at laguna, the differences will be seen , and thats the point of this.
street cars dont push brakes , racing does! (and if your street set up is not up to your task, put on some racing brake pads and that should solve the issue)
remember that race i reported back from?? one of the evo lancers was cooking and boiling fluid??? he had brembo big reds, 13 " rotors. basically more than i had ....... his lap times were 4 seconds slower......... i had no issues....... same tires., same pagid orange race pads....same weight of car, same hp...... same day..... same track.......... hmmmmmmmm
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
PS as for the video------ all i have to say is wow, really? 3500 lb car vs 1700lb racer car on race rubber??? with aero, and tuned suspenson to optimize stopping power and weight transfer?
09-10-2012, 10:31 PM
#63
Nordschleife Master
I find this funny.
Too much braking and/or too thin pads.
I always recall, with a laugh, some advice from an instructor: "I don't think you need to brake there."
The key to fast lap times is fast cornering and that means less braking. Gotta be smooth and know and trust your car. Or be a maniac but that only lasts for a while.
one of the evo lancers was cooking and boiling fluid??? he had brembo big reds, 13 " rotors. basically more than i had ....... his lap times were 4 seconds slower......... i had no issues....... same tires., same pagid orange race pads....same weight of car, same hp...... same day..... same track.......... hmmmmmmmm
I always recall, with a laugh, some advice from an instructor: "I don't think you need to brake there."
The key to fast lap times is fast cornering and that means less braking. Gotta be smooth and know and trust your car. Or be a maniac but that only lasts for a while.
09-10-2012, 10:47 PM
#64
Addict
Rennlist Member
Rennlist Member
If you stop a 928 from 100kph, your brake system (16kg of cast iron in the front rotors alone) absorbs about 579kJ of heat: 36kJ per kg, enough to warm those rotors up by 67ºc (assuming that the front rotors do all the work).
F1 rotors weigh 1kg apiece. When the F1 car slows from 350kph to 70kph, the brakes are turning about 2.9MJ of kinetic energy into thermal energy (and some light?). That's 700kJ per kg. If the specific heat capacity of the brake disks were twice that of iron (a conservatively high guess—http://www.sglgroup.com/cms/internat...ml?__locale=en) and the rotors didn't dissipate heat quickly, one time braking from 350 to 70 would heat the rotors about 700ºc.
That's why F1 brake systems have to dissipate as much heat as possible as quickly, and why our brakes don't.
F1 rotors don't conduct heat well. The heat stays near the surface of the rotor, and is blown away by turbines and such.
F1 rotors weigh 1kg apiece. When the F1 car slows from 350kph to 70kph, the brakes are turning about 2.9MJ of kinetic energy into thermal energy (and some light?). That's 700kJ per kg. If the specific heat capacity of the brake disks were twice that of iron (a conservatively high guess—http://www.sglgroup.com/cms/internat...ml?__locale=en) and the rotors didn't dissipate heat quickly, one time braking from 350 to 70 would heat the rotors about 700ºc.
That's why F1 brake systems have to dissipate as much heat as possible as quickly, and why our brakes don't.
F1 rotors don't conduct heat well. The heat stays near the surface of the rotor, and is blown away by turbines and such.
09-11-2012, 12:04 AM
#65
Drifting
so wrong on so many fronts, i dont know where to start.
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
PS as for the video------ all i have to say is wow, really? 3500 lb car vs 1700lb racer car on race rubber??? with aero, and tuned suspenson to optimize stopping power and weight transfer?
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
PS as for the video------ all i have to say is wow, really? 3500 lb car vs 1700lb racer car on race rubber??? with aero, and tuned suspenson to optimize stopping power and weight transfer?
I was waiting for your voice of experience sermon. Save it. None of the stuff I posted is mine. It is physics, it is govt. and industry studies, and it is Formula 1 website material. All of it.
You have to know when to stay quiet, when you are out of your league. That's why I use experts when I am not. You would simply be laughed out of the classroom on this. Trying to say the rules of physics that apply to everyone except for you in your car is preposterous.
09-11-2012, 12:31 PM
#66
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09-11-2012, 01:01 PM
#67
Drifting
maybe this will help, Concepts of Physics in bold, the rest from eggheads that know their ****. And yes it is as simple as I can make it and it applies to everyone.
First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed .................When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat
Static friction is friction between two or more solid objects that are not moving relative to each other.
An example of static friction is the force that prevents a car wheel from slipping as it rolls on the ground. Even though the wheel is in motion, the patch of the tire in contact with the ground is stationary relative to the ground, so it is static rather than kinetic friction. The maximum value of static friction, is also known as traction
As long as the ABS or the talented driver prevents lock-up (tire slipping) static friction is in effect and the brakes will convert the kinetic energy of the moving car into heat energy, NOT THE TIRE, it is not slipping relative to the pavement. The instant sliding occurs, static friction is no longer applicable—the friction between the two surfaces is then called kinetic friction. And once sliding it will take much longer to stop and tires will get hot and dissipate some of the heat.
First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed .................When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat
Static friction is friction between two or more solid objects that are not moving relative to each other.
An example of static friction is the force that prevents a car wheel from slipping as it rolls on the ground. Even though the wheel is in motion, the patch of the tire in contact with the ground is stationary relative to the ground, so it is static rather than kinetic friction. The maximum value of static friction, is also known as traction
As long as the ABS or the talented driver prevents lock-up (tire slipping) static friction is in effect and the brakes will convert the kinetic energy of the moving car into heat energy, NOT THE TIRE, it is not slipping relative to the pavement. The instant sliding occurs, static friction is no longer applicable—the friction between the two surfaces is then called kinetic friction. And once sliding it will take much longer to stop and tires will get hot and dissipate some of the heat.
Last edited by tv; 09-11-2012 at 04:23 PM.
09-11-2012, 01:02 PM
#68
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so wrong on so many fronts, i dont know where to start.
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
PS as for the video------ all i have to say is wow, really? 3500 lb car vs 1700lb racer car on race rubber??? with aero, and tuned suspenson to optimize stopping power and weight transfer?
I dont know where you got the brake information, but it sounds very overly simplified.
Mk
PS as for the video------ all i have to say is wow, really? 3500 lb car vs 1700lb racer car on race rubber??? with aero, and tuned suspenson to optimize stopping power and weight transfer?
I was waiting for your voice of experience sermon. Save it. None of the stuff I posted is mine. It is physics, it is govt. and industry studies, and it is Formula 1 website material. All of it.
You have to know when to stay quiet, when you are out of your league. That's why I use experts when I am not. You would simply be laughed out of the classroom on this. Trying to say the rules of physics that apply to everyone except for you in your car is preposterous.
09-11-2012, 01:14 PM
#69
Nordschleife Master
maybe this will help, Concepts of Physics in bold, the rest from eggheads that know their ****. And yes it is as simple as I can make it and it applies to everyone.
First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed .................When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat
Static friction is friction between two or more solid objects that are not moving relative to each other.
An example of static friction is the force that prevents a car wheel from slipping as it rolls on the ground. Even though the wheel is in motion, the patch of the tire in contact with the ground is stationary relative to the ground, so it is static rather than kinetic friction. The maximum value of static friction, is also known as traction
As long as the ABS or the talented driver prevents lock-up (tire slipping) static friction is in effect and the brakes will dissipate the kinetic energy of the moving car into heat energy, NOT THE TIRE, it is not slipping relative to the pavement. The instant sliding occurs, static friction is no longer applicable—the friction between the two surfaces is then called kinetic friction. And once sliding it will take much longer to stop and tires will get hot and dissipate some of the heat.
First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed .................When a car comes down a straight line at 300 km/h or more, it possesses lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can instead only be converted one form into another, the only way to slow down the car is to convert the kinetic energy into another form. Brakes as we know them both in race cars and road cars convert this movement energy to heat
Static friction is friction between two or more solid objects that are not moving relative to each other.
An example of static friction is the force that prevents a car wheel from slipping as it rolls on the ground. Even though the wheel is in motion, the patch of the tire in contact with the ground is stationary relative to the ground, so it is static rather than kinetic friction. The maximum value of static friction, is also known as traction
As long as the ABS or the talented driver prevents lock-up (tire slipping) static friction is in effect and the brakes will dissipate the kinetic energy of the moving car into heat energy, NOT THE TIRE, it is not slipping relative to the pavement. The instant sliding occurs, static friction is no longer applicable—the friction between the two surfaces is then called kinetic friction. And once sliding it will take much longer to stop and tires will get hot and dissipate some of the heat.
Unfortunate.
09-11-2012, 01:18 PM
#71
Dude, you realy need to take a brake from here.
09-11-2012, 01:22 PM
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09-11-2012, 01:23 PM
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Dude, you realy need to take a brake from here.
09-11-2012, 01:30 PM
#75
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Quote:
Originally Posted by RPetty2
Why do u guys say don't do this don't do that? I can do whatever I want
Quote: Posted by MainePorsche
Ah, at last. This sums it all up.
In some prior thread, I commented that "....cognitive deficit ? Maybe a little patience warranted ?" Even had a brief PM discussion with another about this.
In one of RPetty2's priors, he stated he has a 504 learning disability.
OK, so...
On our part maybe a little appreciation of the source is in order. I found/find it incredibly frustrating to try to give advise or instruction.
On his part, he really should consider having someone help him post for tech advisement (dad).
If he doesn't do this, he will find himself to be a lonely poster on this forum. The unfortunate result of this would not be unwarranted.
__________________
If one incites this type, this is all we will get. He is unable to get it at best, rude and thoughtless at worst. If there's no replies, he will wither on the vine.
Originally Posted by RPetty2
Why do u guys say don't do this don't do that? I can do whatever I want
Quote: Posted by MainePorsche
Ah, at last. This sums it all up.
In some prior thread, I commented that "....cognitive deficit ? Maybe a little patience warranted ?" Even had a brief PM discussion with another about this.
In one of RPetty2's priors, he stated he has a 504 learning disability.
OK, so...
On our part maybe a little appreciation of the source is in order. I found/find it incredibly frustrating to try to give advise or instruction.
On his part, he really should consider having someone help him post for tech advisement (dad).
If he doesn't do this, he will find himself to be a lonely poster on this forum. The unfortunate result of this would not be unwarranted.
__________________
Last edited by MainePorsche; 09-11-2012 at 02:37 PM.