BBK Myths
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Joined: Jul 2005
Posts: 415
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Wow, so I was wondering why his first post was accurate talking about kinetic energy getting turned into heat when OP doesn't even seem to know basic physics/engineering.
Turns out he plagarized stoptech without linking his source:
http://www.stoptech.com/technical-su...rade-selection
bad form op, bad form.
Turns out he plagarized stoptech without linking his source:
http://www.stoptech.com/technical-su...rade-selection
bad form op, bad form.
op is an idiot. seems like he is butthurt because he cannot buy a BBK so he is bashing all the "stock" G35 for having them.
put 2" rotors on your G35 and go down the nearest mountain rd and tell me fade only happens in the pads.
Heat builds up in the pads because the heat into the brake system is greater than the heat being dissipated by the brake system. Larger rotors with internal vanes dissipate heat better.
Keep spewing your garbage and making up the rules as you go along to validate your original post.
Totopo...were wasting our time here.
put 2" rotors on your G35 and go down the nearest mountain rd and tell me fade only happens in the pads.
Heat builds up in the pads because the heat into the brake system is greater than the heat being dissipated by the brake system. Larger rotors with internal vanes dissipate heat better.
Keep spewing your garbage and making up the rules as you go along to validate your original post.
Totopo...were wasting our time here.
Small clarifcation. Larger rotors with more mass are able to absorb heat and dissipate the heat in a more controlled manner vs rotors with less mass. But basically
Wow, so I was wondering why his first post was accurate talking about kinetic energy getting turned into heat when OP doesn't even seem to know basic physics/engineering.
Turns out he plagarized stoptech without linking his source:
http://www.stoptech.com/technical-su...rade-selection
bad form op, bad form.
Turns out he plagarized stoptech without linking his source:
http://www.stoptech.com/technical-su...rade-selection
bad form op, bad form.
An oem brake setup with DOT 4 fluid and carbotech xp8 pads would be more braking ability than any street driven car would ever need. BBK's are bought mainly for looks. Someone saying a BBK stops a lot shorter is the same type of idiot that says their intake netted them 30whp.
BUT I love BBK's because they look great and really do greatly reduce fade, and they also allow you to run 2 piece rotors which are MUCH lighter than normal rotors.
BUT I love BBK's because they look great and really do greatly reduce fade, and they also allow you to run 2 piece rotors which are MUCH lighter than normal rotors.
Registered User
Joined: Jul 2005
Posts: 415
Likes: 58
Alright, pretty sure WhosUrBuddies is trolling this thread hard.I know I'm probably wasting time but I like doing the reading, and maybe I can convince some other people about reality.
let's take a look:
lol. Hoping to fool people with that term? The difference in specific heat between brake fluids is probably inconsequential. Similarly the 100 grams or so of stainless steal over an insulated core isn't going to be doing anything, nor will it have significant effect on the heat capacity of the system.
the 350z is pretty notorious for brake fade on the track (more of them track). even with the brembos.
I know it gets thrown around a lot, but I don't know if there is actually any real data on the whole gas boundary layer thing. I guess that is just semantics, in any event, no matter what the mechanism, the point is that brake fade happens is when the coefficient of friction drops with higher temperatures. The issue is that all brake pads eventually fade. And there is a limit to the brake pad you can run.
From wikipedia:
"An incorrect explanation sometimes given for brake fade is heated brake shoes evaporate to generate gas that separate them from the drum. Such effects are easy to imagine, but physically impossible, due to the large volume of gas that would be required for such an effect. A gas bearing would need gas replenishment as fast as the disc or drum moves, since it has no gas on its surface as it approaches the pad or shoe. Also, disc brakes use much the same materials and operate well with little fade, even when the discs are glowing hot.'(color vs. temperature)' If brake materials outgassed at drum temperatures, they would also outgas at disc temperatures and would fade substantially. Since discs have little fade, they also demonstrate outgassing is not a source of fade. "
http://en.wikipedia.org/wiki/Brake_fade
Also, when you boil your fluid, you don't completely loose all braking power. You lose a lot of braking power, because of the compressibility of water in the gas phase as opposed to a fluid, but it still transmits some force.
A picture of brake fade:
The ferodo ds2500's are pretty good hybrid street/track use, and they still suffer serious fade after 300C, which isn't too hard to hit.
hehe, are those numbers for a go-kart track? Look up a video with speeds on thunderhill, that is absolutely brutal on the brakes, many like 100-50 braking zones back to back.
That formula is incorrect for calculating work done by braking. That is the work done pushing an object against friction at a constant velocity. work done changing an objects velocity is basically equal to the change in energy.
δE = δQ - δW.
In case you know calculus you can derive it to prove it to yourself:
http://en.wikipedia.org/wiki/Work_(p...ergy_principle
from the text you copied-pasted, it states as such:
http://www.stoptech.com/technical-su...rade-selection
This is kind of what convinced me you are trolling. You are selectively quoting stuff from an article that completely goes against what you are saying.
from the article:
http://www.zeckhausen.com/Testing_Br...rmance%20Model
And then you post the brake temperatures for the rear brakes while neglecting the front, to give the illusion that the bigger stoptech rotors are getting hotter, when in fact the stoptechs use the stock non-brembo rears. If you look at the front temps, they are594 for the 355mm to 721 for brembo
the math is pretty easy, as above. 3x the energy from 120-60 as 0-60. It is not difficult at all to calculate the work done. It is path-independent so uneven deceleration rate is non-issue.
let's take a look:
The conclusion isnt false. I also stated that SS lines and RBF fluid would greatly increase heat capacity of stock brakes. OEM brakes can handle quite a bit of heat. Many many people track their cars with OEM brakes without any issues. Still how often will you really do repeated 0-60 stops?
the 350z is pretty notorious for brake fade on the track (more of them track). even with the brembos.
Almost all dynamic brake fade is due to the quality of the brake pad (ie ebay modders) and not the heat capacity of the system. Majority of the time when brake fade occurs, the brake pad is actually skidding on a film of gas created by the over heating of the materials of the brake pad.
Brake fade should not be confused with fluid vapor lock. When you overheat the fluid and get vapor lock in your system, you loose all braking power completely.
Brake fade should not be confused with fluid vapor lock. When you overheat the fluid and get vapor lock in your system, you loose all braking power completely.
From wikipedia:
"An incorrect explanation sometimes given for brake fade is heated brake shoes evaporate to generate gas that separate them from the drum. Such effects are easy to imagine, but physically impossible, due to the large volume of gas that would be required for such an effect. A gas bearing would need gas replenishment as fast as the disc or drum moves, since it has no gas on its surface as it approaches the pad or shoe. Also, disc brakes use much the same materials and operate well with little fade, even when the discs are glowing hot.'(color vs. temperature)' If brake materials outgassed at drum temperatures, they would also outgas at disc temperatures and would fade substantially. Since discs have little fade, they also demonstrate outgassing is not a source of fade. "
http://en.wikipedia.org/wiki/Brake_fade
Also, when you boil your fluid, you don't completely loose all braking power. You lose a lot of braking power, because of the compressibility of water in the gas phase as opposed to a fluid, but it still transmits some force.
A picture of brake fade:
The ferodo ds2500's are pretty good hybrid street/track use, and they still suffer serious fade after 300C, which isn't too hard to hit.
I dont have to discredit the question because it had no credit to begin with. This is the real world not a video game; in what world is 200-0 a feasible situation? When have you ever heard of a car locking it up at 200 mph, let alone a G35? Multiple 70-0 stops are not credible either. Track driving usually involves 70-50 or 50-20, ie slow downs, not full stops. In what situation would you ever see multiple 70-0 stops? Please pose realistic questions if you want real answers.
Also if you want to claim more heat is generated from a 120-60 than 60-0, please prove it. Unsubstantiated claims with not factual evidence are of no use to anyone. To help you out, here is the forumla to calculate work done by brakes (assuming perfect brake bias and no weight distribution.
W=Cf*m*g*d
W=Cf*m*g*d
δE = δQ - δW.
In case you know calculus you can derive it to prove it to yourself:
http://en.wikipedia.org/wiki/Work_(p...ergy_principle
from the text you copied-pasted, it states as such:
2) The brakes function by converting the kinetic energy of the car into thermal energy during deceleration - producing heat, lots of heat - which must then be transferred into the surroundings and into the air stream.
The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.
The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.
For the thousandth time now. Brake fade is determined by the pad material and is independent of rotor size. Heat generated is a function of the coefficient of friction of the pad and rotor, as well as the rotor material.
A test was done between the stock Brembo brakes and Stoptech upgraded BBK.
The car through twenty back-to-back stops, the first ten from 60mph, followed by six stops from 80mph and then four stops from 100mph.. Each time the car stopped, the rotor temperatures where measured and then sent the car around for another pass. After 20 passes on stock brakes, Stoptech front 332mm BBK was installed and test done again.
After 20 repeated stops, no brake fade was recorded. There was almost no difference in stopping distance. And the Stoptech BBK recorded much higher temps than the stock Brembos due to material difference of the rotors. While the tires were the same, each test did have different pad material and friction coefficients (brembo vs stoptech) so it still isn't a true 1-1 comparison.
Brembo avg 60-0 stop distance - 117.3 ft
Brembo avg 60-0 rotor temp - 371 F
Brembo avg 80-0 stop distance - 208.7 ft
Brembo avg 80-0 rotor temp - 395 F
Brembo avg 100-0 stop distance - 328.3 ft
Brembo avg 100-0 rotor temp - 477 F
Stoptech BBK avg 60-0 stop distance - 115.8 ft
Stoptech BBK avg 60-0 rotor temp - 436 F
Stoptech BBK avg 80-0 stop distance - 206.7 ft
Stoptech BBK avg 80-0 rotor temp - 418 F
Stoptech BBK avg 100-0 stop distance - 326.9 ft
Stoptech BBK avg 100-0 rotor temp - 510 F
A test was done between the stock Brembo brakes and Stoptech upgraded BBK.
The car through twenty back-to-back stops, the first ten from 60mph, followed by six stops from 80mph and then four stops from 100mph.. Each time the car stopped, the rotor temperatures where measured and then sent the car around for another pass. After 20 passes on stock brakes, Stoptech front 332mm BBK was installed and test done again.
After 20 repeated stops, no brake fade was recorded. There was almost no difference in stopping distance. And the Stoptech BBK recorded much higher temps than the stock Brembos due to material difference of the rotors. While the tires were the same, each test did have different pad material and friction coefficients (brembo vs stoptech) so it still isn't a true 1-1 comparison.
Brembo avg 60-0 stop distance - 117.3 ft
Brembo avg 60-0 rotor temp - 371 F
Brembo avg 80-0 stop distance - 208.7 ft
Brembo avg 80-0 rotor temp - 395 F
Brembo avg 100-0 stop distance - 328.3 ft
Brembo avg 100-0 rotor temp - 477 F
Stoptech BBK avg 60-0 stop distance - 115.8 ft
Stoptech BBK avg 60-0 rotor temp - 436 F
Stoptech BBK avg 80-0 stop distance - 206.7 ft
Stoptech BBK avg 80-0 rotor temp - 418 F
Stoptech BBK avg 100-0 stop distance - 326.9 ft
Stoptech BBK avg 100-0 rotor temp - 510 F
from the article:
http://www.zeckhausen.com/Testing_Br...rmance%20Model
Stopping the 350Z Performance Model from 80 mph
After six stops from 80mph, and then four stops from 100 mph, the front rotors reached 804 °F and the stopping distances began to increase as fade set in. I began to wonder which way to dive if the car couldn't stop, but figured the test driver would expect us to stay still and would swerve around us. I kicked myself for not asking about this before we started! Stopping distances from 80mph and 100mph averaged 210.5 and 333.6 feet respectively. That's within 5 feet at 100 mph and within 2 feet from 80 mph of the 350Z Track Model's performance. The Brembo brakes didn't seem to make a significant difference on stopping performance until the cars started doing repeated 100mph stops, at which point the increased thermal capacity of the bigger rotors kept brake fade at bay, while the Performance model with smaller brakes began to experience fade.
After six stops from 80mph, and then four stops from 100 mph, the front rotors reached 804 °F and the stopping distances began to increase as fade set in. I began to wonder which way to dive if the car couldn't stop, but figured the test driver would expect us to stay still and would swerve around us. I kicked myself for not asking about this before we started! Stopping distances from 80mph and 100mph averaged 210.5 and 333.6 feet respectively. That's within 5 feet at 100 mph and within 2 feet from 80 mph of the 350Z Track Model's performance. The Brembo brakes didn't seem to make a significant difference on stopping performance until the cars started doing repeated 100mph stops, at which point the increased thermal capacity of the bigger rotors kept brake fade at bay, while the Performance model with smaller brakes began to experience fade.
But it said that doubling speed will quadruple brake temperature, meaning that a 120-0 stop will generate 4 times the heat as 60-0 stop. It doesnt say anything about 120-60. Deceleration rate is not constant so it is actually pretty difficult to determine the work done from a 120-60 braking event. I really don't feel like doing to the math to show what the difference in heat generation would actually be. Also it doesn't account for the higher heat transfer to the air due to higher velocity.
Joined: Oct 2005
Posts: 14,494
Likes: 996
From: Neverland
Toto, please go back and re read. But here is a quick summary for you.
If you want to improve your stopping distance, get better tires.
If you want to reduce brake fade, get better pads.
If you want to prevent vapor lock, get better brake fluid and lines.
If you want to improve visual appearance of your car, get a BBK.
If you want to improve your stopping distance, get better tires.
If you want to reduce brake fade, get better pads.
If you want to prevent vapor lock, get better brake fluid and lines.
If you want to improve visual appearance of your car, get a BBK.
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