to pccb or not to...
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many thanks 4 the advice everyone
I just e-mailed the dealer that took my order
Hopefully it won't be too late to get pccb
If not ,big red should be good enough for my time in Europe
When I return to the US next year,I will be ready to mod my car,and can always upgrade brakes as well
Regards and happy motoring to all
I just e-mailed the dealer that took my order
Hopefully it won't be too late to get pccb
If not ,big red should be good enough for my time in Europe
When I return to the US next year,I will be ready to mod my car,and can always upgrade brakes as well
Regards and happy motoring to all
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Posts: 1,276
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Doesn't anyone care about performance? The PCCBs should make your car accelerate fatster and handle better since the rotors are 1/2 the weight of the regular brakes.
Let me explain this a little further. PCCBs weigh about 1/2 as much as regular brakes. I believe regular 997 rotors weigh 24 pounds, hence you are saving 12 pounds in each corner. 48 pounds of rotational weight is equal to 480 pounds of static weight which is equivalent to about 48hp. I would bet that in a straight line race starting from 0 that a stock 997TT with PCCBs would start to walk away from a stock 997TT without PCCBs.
Let me explain this a little further. PCCBs weigh about 1/2 as much as regular brakes. I believe regular 997 rotors weigh 24 pounds, hence you are saving 12 pounds in each corner. 48 pounds of rotational weight is equal to 480 pounds of static weight which is equivalent to about 48hp. I would bet that in a straight line race starting from 0 that a stock 997TT with PCCBs would start to walk away from a stock 997TT without PCCBs.
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Posts: 333
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For your viewing pleasure:
Unsprung Weight - Part 2
By: Eric Albert
Introduction
In the first part of this series, we took a look at the effects of high unsprung weight on suspension and handeling. In this part, we will look at rotating mass. Be careful not to confuse unsprung mass with rotating mass. Reducing both is good, but they are not the same. Let's take a look.
Rotational Inertia (or Momentum)
Rotational inertia is a concept a bit more difficult to deal with than unsprung weight. Inertia can be thought of as why a car wants to keep rolling once moving, or remain in place once stopped (unless you forget to set the parking brake on that hill). I believe the terms momentum and inertia are interchangeable. The term “flywheel effect” also refers to these concepts. In a car, there are a number of rotating masses which require energy to accelerate. Up front, ignoring the internal engine components like the crankshaft, we have to worry about the flywheel, clutch assembly, gears, axles, brake rotors and wheel/tire. Out back its a little simpler (for FWD) with just the brakes and wheel/tire contributing most of the mass.
The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels provide more responsive acceleration and braking.
Before continuing with our informal analysis here, I want to point out something very important about rotational inertia. We’ve all seen the ice skating move where the skater starts spinning. She pulls her arms in and speeds up, then extends them again and slows down. Why is this? Well, the further a mass is from the center of rotation, the faster it must travel for a given angular speed (how many degrees of an arc it traverses per time unit). The faster anything moves, the more energy it has, so when the arms are pulled in, conservation of energy says that the rotation rate must increase due to equal energy being applied to the same mass over a smaller diameter. Applying this to wheels and tires, which have most of their mass spread as far as possible from the rotation center, I think you’ll agree that it naturally takes more energy to accelerate them. Example: Take a two identical masses, but one is a solid disk of diameter D, the other is a ring of diameter 2D. The ring will require more force to accelerate it (in a rotational manner). Therefore a heavier rim with a smaller diameter could have less rotational mass than a lighter rim of a larger size, and accelerate faster with the same force applied.
The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.
Because of this, the weight of rotating mass such as wheels and tires on a car have a bigger effect on acceleration than static weight such as on the chassis on a car. When purchasing new wheels and tires for a performance car, it can be useful to compare the effects of different wheel and tire combinations. This is especially true when considering upgrading to larger wheels or tires on a car.
The use of light-weight alloys in wheels reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of light alloy wheels on vehicle performance cannot be overlooked.
For example:
A reduction in the weight of the rim/tire assembly of 5lbs x 4 (all around the car) is equivalent to a 200lb weight reduction in vehicle weight (thats worth 0.200 in the 1/4 mile)
So What's the Point?
The point of this discussion is as follows: There is a great deal of rotational mass to deal with in a car and tires and wheels may only make up half of it. Estimates for weight (o.k. for comparison since they’re all in the same gravity field, therefore the mass would be a similar ratio)
Front: Rear:
Wheel/tire: 30-35 lbs each 30-35 lbs each
Flywheel: 15-20 lbs
Clutch: 15 lbs
Halfshafts: 7-10 lbs each
Gears: 5-7 lbs
Rotors: 3-5 lbs 3-5 lbs
Misc: 3-5 lbs 3-5 lbs
------------------------------------------------------------------
Total: 115-148 lbs 76-90 lbs
So a couple pounds here and there on wheels and tires will make a difference, but that difference is magnified because that weight is placed further from the axis of rotation than any other mentioned (remember the ice skater). All these masses must be accelerated, so any reduction is a good thing. Now you know why we always say don't get those 18" rims for your civic. Not only are the heavier, they have a larger overall diameter. Even with lower profile tires, most plus sizing leaves us with a slightly larger wheel.
Last edited by SleeperX; May 19, 2008 at 04:46 AM.
Thread Starter
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Registered User
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From: Naples,Florida
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Thanks for the detailed and informative reply.
Unfortunately,it was too late to change my order,so I will have to make do with Big red while I am in Europe for the next 6 months.
I will just have to wait till I get back to the US next year,by which time I will probably be ready to give my car a general mod...
One more question though,:if even Porsche may have had some reliability issues with the first generation pccb,how could I be sure of the reliability of components from a smaller after-market shop?just curious
Happy and safe driving to all
Unfortunately,it was too late to change my order,so I will have to make do with Big red while I am in Europe for the next 6 months.
I will just have to wait till I get back to the US next year,by which time I will probably be ready to give my car a general mod...
One more question though,:if even Porsche may have had some reliability issues with the first generation pccb,how could I be sure of the reliability of components from a smaller after-market shop?just curious
Happy and safe driving to all
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Joined: Apr 2008
Posts: 20
From: Texas
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also, what are some things that can crack/chip a ceramic rotor? and do the pads last longer? what about pad deposits and vibration?
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Joined: Dec 2007
Posts: 333
From: New York
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I will break out my physics books this weekend. It is my understaning and I have read in many places that 100 pounds is equivalent to about 10hp.
https://www.6speedonline.com/forums/...ad.php?t=71489
In the above mentioned link, it is noted that 300pounds is equivalent to 47hp or about 15.7hp per 100 pounds.
https://www.6speedonline.com/forums/...ad.php?t=71489
In the above mentioned link, it is noted that 300pounds is equivalent to 47hp or about 15.7hp per 100 pounds.
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Posts: 3,315
From: WA state
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I too have heard 100 lbs is equal to 10hp - not exact science mind you but generally 'accepted' - at least by those who dreamed it up 
Anyways, if your penny pinching at the higher levels of the options list simply dont check off the PCCB's. An exhaust and flash + 10 extra minutes washing the car will more than make up for the difference if you have any regrets after the fact.
I decided not to get them and instead invest the $ down the road on aftermarket wheels + other mods. That decision was easy, it was my first Porsche and I had no experience with a PCCB'd car. Might be a different story if I had owned one before with them and noticed the difference. All my searches online showed a lot of people swapping them out and complaing about them, have to admit that freaked me out a bit.
Anyways, if your penny pinching at the higher levels of the options list simply dont check off the PCCB's. An exhaust and flash + 10 extra minutes washing the car will more than make up for the difference if you have any regrets after the fact.
I decided not to get them and instead invest the $ down the road on aftermarket wheels + other mods. That decision was easy, it was my first Porsche and I had no experience with a PCCB'd car. Might be a different story if I had owned one before with them and noticed the difference. All my searches online showed a lot of people swapping them out and complaing about them, have to admit that freaked me out a bit.
Last edited by gmoney; May 19, 2008 at 10:40 AM.
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I really regret not getting the PCCBs but there was alot of availability problems with them during my order. I even saw a GT3RS on the showroom floor of my dealer with no PCCBs presumably for the same reason, availability problems, dunno how true that was. Oh well, next time definitely going with PCCBs.
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Joined: Feb 2006
Posts: 1,524
From: Long Island
Rep Power: 94
Doesn't anyone care about performance? The PCCBs should make your car accelerate fatster and handle better since the rotors are 1/2 the weight of the regular brakes.
Let me explain this a little further. PCCBs weigh about 1/2 as much as regular brakes. I believe regular 997 rotors weigh 24 pounds, hence you are saving 12 pounds in each corner. 48 pounds of rotational weight is equal to 480 pounds of static weight which is equivalent to about 48hp. I would bet that in a straight line race starting from 0 that a stock 997TT with PCCBs would start to walk away from a stock 997TT without PCCBs.
Let me explain this a little further. PCCBs weigh about 1/2 as much as regular brakes. I believe regular 997 rotors weigh 24 pounds, hence you are saving 12 pounds in each corner. 48 pounds of rotational weight is equal to 480 pounds of static weight which is equivalent to about 48hp. I would bet that in a straight line race starting from 0 that a stock 997TT with PCCBs would start to walk away from a stock 997TT without PCCBs.
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Joined: Dec 2007
Posts: 333
From: New York
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Chris,
How are you? Ask me that quesiton in 2 weeks? Maybe we could meet up after Memorial Day? Would be good to catch up. How are you enjoying your car?
How are you? Ask me that quesiton in 2 weeks? Maybe we could meet up after Memorial Day? Would be good to catch up. How are you enjoying your car?
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Joined: Apr 2008
Posts: 166
From: Covington, Louisiana
Rep Power: 39
I too have heard 100 lbs is equal to 10hp - not exact science mind you but generally 'accepted' - at least by those who dreamed it up
Anyways, if your penny pinching at the higher levels of the options list simply dont check off the PCCB's. An exhaust and flash + 10 extra minutes washing the car will more than make up for the difference if you have any regrets after the fact.
I decided not to get them and instead invest the $ down the road on aftermarket wheels + other mods. That decision was easy, it was my first Porsche and I had no experience with a PCCB'd car. Might be a different story if I had owned one before with them and noticed the difference. All my searches online showed a lot of people swapping them out and complaing about them, have to admit that freaked me out a bit.
Anyways, if your penny pinching at the higher levels of the options list simply dont check off the PCCB's. An exhaust and flash + 10 extra minutes washing the car will more than make up for the difference if you have any regrets after the fact.
I decided not to get them and instead invest the $ down the road on aftermarket wheels + other mods. That decision was easy, it was my first Porsche and I had no experience with a PCCB'd car. Might be a different story if I had owned one before with them and noticed the difference. All my searches online showed a lot of people swapping them out and complaing about them, have to admit that freaked me out a bit.
So if I take that weight-saving rule of thumb to the extreme, my TT disappears but I'll have 830 hp.
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I'll see you in a few weeks. I love the car. Was on an F430 kick for a couple of months but I'm very happy right now.
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You walk away from a 997TT with PCCB rotors. A stock 997TT that is putting out 480hp vs. your 530hp? POssibly driver error if that is the case.
For your viewing pleasure:
Unsprung Weight - Part 2
By: Eric Albert
Introduction
In the first part of this series, we took a look at the effects of high unsprung weight on suspension and handeling. In this part, we will look at rotating mass. Be careful not to confuse unsprung mass with rotating mass. Reducing both is good, but they are not the same. Let's take a look.
Rotational Inertia (or Momentum)
Rotational inertia is a concept a bit more difficult to deal with than unsprung weight. Inertia can be thought of as why a car wants to keep rolling once moving, or remain in place once stopped (unless you forget to set the parking brake on that hill). I believe the terms momentum and inertia are interchangeable. The term “flywheel effect” also refers to these concepts. In a car, there are a number of rotating masses which require energy to accelerate. Up front, ignoring the internal engine components like the crankshaft, we have to worry about the flywheel, clutch assembly, gears, axles, brake rotors and wheel/tire. Out back its a little simpler (for FWD) with just the brakes and wheel/tire contributing most of the mass.
The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels provide more responsive acceleration and braking.
Before continuing with our informal analysis here, I want to point out something very important about rotational inertia. We’ve all seen the ice skating move where the skater starts spinning. She pulls her arms in and speeds up, then extends them again and slows down. Why is this? Well, the further a mass is from the center of rotation, the faster it must travel for a given angular speed (how many degrees of an arc it traverses per time unit). The faster anything moves, the more energy it has, so when the arms are pulled in, conservation of energy says that the rotation rate must increase due to equal energy being applied to the same mass over a smaller diameter. Applying this to wheels and tires, which have most of their mass spread as far as possible from the rotation center, I think you’ll agree that it naturally takes more energy to accelerate them. Example: Take a two identical masses, but one is a solid disk of diameter D, the other is a ring of diameter 2D. The ring will require more force to accelerate it (in a rotational manner). Therefore a heavier rim with a smaller diameter could have less rotational mass than a lighter rim of a larger size, and accelerate faster with the same force applied.
The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.
Because of this, the weight of rotating mass such as wheels and tires on a car have a bigger effect on acceleration than static weight such as on the chassis on a car. When purchasing new wheels and tires for a performance car, it can be useful to compare the effects of different wheel and tire combinations. This is especially true when considering upgrading to larger wheels or tires on a car.
The use of light-weight alloys in wheels reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of light alloy wheels on vehicle performance cannot be overlooked.
For example:
A reduction in the weight of the rim/tire assembly of 5lbs x 4 (all around the car) is equivalent to a 200lb weight reduction in vehicle weight (thats worth 0.200 in the 1/4 mile)
So What's the Point?
The point of this discussion is as follows: There is a great deal of rotational mass to deal with in a car and tires and wheels may only make up half of it. Estimates for weight (o.k. for comparison since they’re all in the same gravity field, therefore the mass would be a similar ratio)
Front: Rear:
Wheel/tire: 30-35 lbs each 30-35 lbs each
Flywheel: 15-20 lbs
Clutch: 15 lbs
Halfshafts: 7-10 lbs each
Gears: 5-7 lbs
Rotors: 3-5 lbs 3-5 lbs
Misc: 3-5 lbs 3-5 lbs
------------------------------------------------------------------
Total: 115-148 lbs 76-90 lbs
So a couple pounds here and there on wheels and tires will make a difference, but that difference is magnified because that weight is placed further from the axis of rotation than any other mentioned (remember the ice skater). All these masses must be accelerated, so any reduction is a good thing. Now you know why we always say don't get those 18" rims for your civic. Not only are the heavier, they have a larger overall diameter. Even with lower profile tires, most plus sizing leaves us with a slightly larger wheel.
For your viewing pleasure:
Unsprung Weight - Part 2
By: Eric Albert
Introduction
In the first part of this series, we took a look at the effects of high unsprung weight on suspension and handeling. In this part, we will look at rotating mass. Be careful not to confuse unsprung mass with rotating mass. Reducing both is good, but they are not the same. Let's take a look.
Rotational Inertia (or Momentum)
Rotational inertia is a concept a bit more difficult to deal with than unsprung weight. Inertia can be thought of as why a car wants to keep rolling once moving, or remain in place once stopped (unless you forget to set the parking brake on that hill). I believe the terms momentum and inertia are interchangeable. The term “flywheel effect” also refers to these concepts. In a car, there are a number of rotating masses which require energy to accelerate. Up front, ignoring the internal engine components like the crankshaft, we have to worry about the flywheel, clutch assembly, gears, axles, brake rotors and wheel/tire. Out back its a little simpler (for FWD) with just the brakes and wheel/tire contributing most of the mass.
The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels provide more responsive acceleration and braking.
Before continuing with our informal analysis here, I want to point out something very important about rotational inertia. We’ve all seen the ice skating move where the skater starts spinning. She pulls her arms in and speeds up, then extends them again and slows down. Why is this? Well, the further a mass is from the center of rotation, the faster it must travel for a given angular speed (how many degrees of an arc it traverses per time unit). The faster anything moves, the more energy it has, so when the arms are pulled in, conservation of energy says that the rotation rate must increase due to equal energy being applied to the same mass over a smaller diameter. Applying this to wheels and tires, which have most of their mass spread as far as possible from the rotation center, I think you’ll agree that it naturally takes more energy to accelerate them. Example: Take a two identical masses, but one is a solid disk of diameter D, the other is a ring of diameter 2D. The ring will require more force to accelerate it (in a rotational manner). Therefore a heavier rim with a smaller diameter could have less rotational mass than a lighter rim of a larger size, and accelerate faster with the same force applied.
The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.
Because of this, the weight of rotating mass such as wheels and tires on a car have a bigger effect on acceleration than static weight such as on the chassis on a car. When purchasing new wheels and tires for a performance car, it can be useful to compare the effects of different wheel and tire combinations. This is especially true when considering upgrading to larger wheels or tires on a car.
The use of light-weight alloys in wheels reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of light alloy wheels on vehicle performance cannot be overlooked.
For example:
A reduction in the weight of the rim/tire assembly of 5lbs x 4 (all around the car) is equivalent to a 200lb weight reduction in vehicle weight (thats worth 0.200 in the 1/4 mile)
So What's the Point?
The point of this discussion is as follows: There is a great deal of rotational mass to deal with in a car and tires and wheels may only make up half of it. Estimates for weight (o.k. for comparison since they’re all in the same gravity field, therefore the mass would be a similar ratio)
Front: Rear:
Wheel/tire: 30-35 lbs each 30-35 lbs each
Flywheel: 15-20 lbs
Clutch: 15 lbs
Halfshafts: 7-10 lbs each
Gears: 5-7 lbs
Rotors: 3-5 lbs 3-5 lbs
Misc: 3-5 lbs 3-5 lbs
------------------------------------------------------------------
Total: 115-148 lbs 76-90 lbs
So a couple pounds here and there on wheels and tires will make a difference, but that difference is magnified because that weight is placed further from the axis of rotation than any other mentioned (remember the ice skater). All these masses must be accelerated, so any reduction is a good thing. Now you know why we always say don't get those 18" rims for your civic. Not only are the heavier, they have a larger overall diameter. Even with lower profile tires, most plus sizing leaves us with a slightly larger wheel.
http://en.wikipedia.org/wiki/Moment_of_inertia
The simpler approach would go something like this;
997TT; 1580kg/480 = 303bhp per tonne.
Ceramics are 5.6kg per corner lighter but that’s included in the above weight. So are the 18 inch wheels (lighter on a 996TT) versus 997TT 19 inch wheels.
My 996TT; 1540kg/530 = 344bhp per tonne.
Just by having PCBS on your car there is no way you can actually gain 48BHP.
So, back in the real world;
997TT from my friend makes the 100-200kmh run in 8.9 secs.
My 996TT does same run in 7.0 secs dead.
No driver errors.
So it must be those PCBS horses you’ve got are either very hungry or very old and tired indeed?
PCBS are better brakes when hot. Period, no question there. However, they are not as good as steels on the initial bite when cold and are actually less suitable for the street if an emergency situation arises more so if they are wet. They are expensive and racing drivers unless pro’s and or money is no object don’t use them. They produce less dust which is good, but be aware of the first generation as they are not as good – prone to chipping. The bottom line? PCBS are better than steel when hot. However the difference is not night and day. Tests have shown that the stopping distances are similar and I am yet to get fade on my brakes in seriously fast street driving with my steels. However once on the track brakes on a 996TT need to be upgraded whilst the 997TT’s ceramics don’t. But then again the ceramics won’t last you 100K on the track like claimed for the street and the replacement will be very costly. So as always there are horses for courses...
Last edited by Terminator; May 20, 2008 at 01:37 AM.
