Brake Pad Dust Issue

[Knightshade]

If brake pads have nothing to do with stopping the car, then internal combustion has nothing to do with moving it. Must be the tires. :D

At the bleeding edge of brake material technology:

SGL Carbon wins award for, among other factors, stopping distance

"The carbon-ceramic brake discs from the SGL Brakes GmbH, a subsidiary of the SGL Group, are manufactured from the innovative composite, carbon-fiber reinforced silicon carbide (CSiC) and offer many benefits. In addition to having a long service life (the length of a car’s service life), half the weight of conventional steel brake discs and almost no abrasion at all (dust emission), improved driving dynamics and a shorter braking distance also represent innovative characteristics of a carbon-ceramic brake system."

"In 2007, the SGL Group is expected to fit approximately 8,000 vehicles from brands including Porsche, Audi, Bentley, Lamborghini and Bugatti."

I spent $8800 on the Porsche PCCB upgrade. By Knightshade's logic, perhaps we should have stopped (pun intended) with drum brakes decades ago.

As I said earlier, quoting marketing materials from the folks trying to convince you to buy their crap isn't the most persuasive thing. There's people trying to sell you magnets that improve your gas mileage too, but it doesn't make it true.

Especially when more honest brake manufacturers openly admit such claims simply aren't true.

Unless you're saying these guys are honest, and Brembo and Stoptech are lying because... why again?

And if you spent $8800 on a brake upgrade and aren't either:

Racing the car

Driving down steep mountains on a near daily basis

Then you're exactly the sucker of a customer these companies love.

[Knightshade]

By the way, here's a review of the PCCB brakes-

http://www.europeancarweb.com/tech/0406ec_...akes/index.html

In it they mention three things-

The PCCB brakes provided -the exact same stopping distance- as stock brakes

and

To improve stopping distance on a porsche you should use stickier tires.

and

"we can say that you'll have to use your Porsche considerably harder than we do to realize a significant benefit with PCCB."

here, let me quote their results to you-

"The car's best 60 to 0 braking distance with stock brakes rounded to 112 ft (our standard braking data procedure), and its best distance rounded to 113 ft with PCCB. In both cases, performance was consistent within a few feet over five stops, with no fade. From 80 to 0, european car's long-term car stopped in 200 ft with PCCB, exactly the same as another stock Carrera 4S tested earlier at the same location. "

Over here we have an -honest- company telling you the benefits of carbon ceramic brake kits-

http://www.gmpperformance.com/index.cfm?PG...&PID=186733

Stoptech lists the many advantages. Stopping distance improvement NOT among them.

[PA350]

By the way, here's a review of the PCCB brakes-

http://www.europeancarweb.com/tech/0406ec_...akes/index.html

In it they mention three things-

The PCCB brakes provided -the exact same stopping distance- as stock brakes

and

To improve stopping distance on a porsche you should use stickier tires.

and

"we can say that you'll have to use your Porsche considerably harder than we do to realize a significant benefit with PCCB."

here, let me quote their results to you-

"The car's best 60 to 0 braking distance with stock brakes rounded to 112 ft (our standard braking data procedure), and its best distance rounded to 113 ft with PCCB. In both cases, performance was consistent within a few feet over five stops, with no fade. From 80 to 0, european car's long-term car stopped in 200 ft with PCCB, exactly the same as another stock Carrera 4S tested earlier at the same location. "

Over here we have an -honest- company telling you the benefits of carbon ceramic brake kits-

http://www.gmpperformance.com/index.cfm?PG...&PID=186733

Stoptech lists the many advantages. Stopping distance improvement NOT among them.

Understood and totally agree.

When I purchased my CaymanS I looked hard into PCCB. Besides the $8k sticker, the benefits to most are little. Three major benefits to PCCB:

1) longer pad life

2) longer rotor life

3) amazing lessening of fade, and greater heat dissapation under race conditions...full on circuit racing, not autox.

Hardly a reason for the majority of owners to shell out that cash.

BillT.

[terry993]

PCCB was about 5.3% of my out the door price on last year's Porsche 997TT purchase. Small price to pay to keep my life and my car on roads like this (Hwy 212 MT) which I have driven 3 times:

Reduced unsprung weight (30# less) for handling was my major reason. Other benefits were ancillary, but I can assure you after 296K miles on 3 Porsches in 19 years, that the $8800 will pay for itself in rotor and pad replacement.

Bill, you will find similar discussion on the Porsche boards. Early adopters, late adopters.

I have now driven steel rotored and PCCB Turbos back to back on canyon roads, and am even more pleased with my decision. Like I was careful to state in my original post about 7 pages ago on the dust free IS brakes, it is just a subjective opinion. I run nice sticky tires, too, as they are part of, but not all of, the result.

And I admit, I enjoy being suckered by the snake oil people. :D

[Knightshade]

Yup, and as I've said all along, there's plenty of reasons one might use different pads (or rotors) including roads like you mention (fade issues), weight (in the rotor case anyway) or for wear/tear reasons.

Just stopping distance is NOT one of those reasons, since pads -can not- reduce that.

[bartkat]

How many miliseconds?

Oops. Time is not in the equation.

My bad.

:lol:

[bartkat]

Statements from people who want to sell you brakes are not valid.

Oops. They're ok if they help you make your point.

My bad. KS makes up the rules as he goes along.

[bartkat]

Brake pads defy the laws of physics by stopping rotating wheels being pushed along by a ton and a half or so of mass at some speed from 60 to maybe 80 MPH instantly, right now, immediately.

Oops. Not true. It's almost, virtually, essentially but not really instantly.

My bad.

[Knightshade]

Barkat, just a suggestion, but have you ever considered understanding the topic you are disucussing before discussing it?

For example, this is the 3rd or 4th time you've mentioned the pads stopping the wheels, when they don't do anything of the sort at all. They aren't even directly connected to the wheels. Those would be the rotors you keep confusing them with.

It's hard to have an intelligent discussion with someone who doesn't even understand the parts they are discussing.

The ABS system takes miliseconds to go from not-braking-at-all to fully engaged.

The pads translate the clamping force from caliper to the rotor -instantly-

Not in milliseconds, but instantly. No time involved. That's why the equation to calculate the force acting on them (and the force they convey onward in the system) doesn't consider time. Time doesn't matter.

The pad itself has no moving parts, why WOULD it take -any- time to translate the force from one part to the other?

You keep insisting it does, but have no idea why it would, since don't even understand what the part you're talking about does, let alone how it does it.

Once again, the list of people who know you are wrong:

Me, The guy who has mutiple degrees in engineering, designs ABS systems for a living, and has written several books on the topic, the people who designed the IS-F brakes, the people who designed the F-sport brakes, the people who did the police brake pad tests, the people who tested the PCCB $8000 braking system, the guy who tested the actual 2IS pads, all the other tech voices on CL, and pretty much everyone on here too.

The people who think you are right:

You.

Just about every person in the thread has ended up agreeing with me so far. Just as they agree with every expert I've cited. NOBODY has ended up agreeing with you once whatever point was in question was explained. I can't imagine why. Can you? Could it be because you're completely wrong? Just a thought.

[clay1]

STOP!

... no pun intended

[JENunnez]

Knightshade note that time is a factor in the pads section.

And that rotor, hub,wheel and tire are all one unit connected mechanically. It may not be 100% efficient but it's still one unit.

The Brake Pads

It is the functional responsibility of the brake pads to generate a frictional force which

opposes the rotation of the spinning rotor assembly. This frictional force is related to the

caliper clamp force as follows:

friction clamp bp F = F × μ

• where Ffriction = the frictional force generated by the brake pads opposing the

rotation of the rotor

• where μbp = the coefficient of friction between the brake pad and the rotor

Note that this relationship assumes 100% mechanical efficiency of all components at the

brake pad interface. In practical application, mechanical deflection (compressibility) of

the brake pad materials and friction found between the brake pad and the caliper body

components prevents this condition. In addition, it should be noted that the coefficient of

friction between the brake pad and the rotor is not a single fixed value, but rather changes

dynamically with time, temperature, pressure, wear, and such.

The Rotor

While the rotor serves as the primary heat sink in the braking system, it is the functional

responsibility of the rotor to generate a retarding torque as a function of the brake pad

frictional force. This torque is related to the brake pad frictional force as follows:

r friction eff T = F × R

• where Tr = the torque generated by the rotor

• where Reff = the effective radius (effective moment arm) of the rotor (measured

from the rotor center of rotation to the center of pressure of the caliper pistons)

Because the rotor is mechanically coupled to the hub and wheel assembly, and because

the tire is assumed to be rigidly attached to the wheel, the torque will be constant

throughout the entire rotating assembly as follows:

t w r T = T = T

• where Tt = the torque found in the tire

• where Tw = the torque found in the wheel

Note that this relationship assumes 100% mechanical efficiency of all components at the

wheel end. In practical application, mechanical deflection and relative motion between

the rotating components prevents this condition.

Copyright © 2005 StopTech LLC

[bartkat]

Barkat, just a suggestion, but have you ever considered understanding the topic you are disucussing before discussing it?

Perhaps you should consider all the variables involved. But you don't so you continue to think the entire stopping process happens at once. It doesn't, it's a process, not an instant event. The disc is part of the wheel and it's the pad friction that stops it. Take the pad away and what happens? I'm sorry but you're clinging to this ignoring all the components simply because the slowing/stopping time of the wheel is left out of most descriptions just to simplify said descriptions. I'm also sorry that I haven't been able to explain this to you in a manner that you can understand or are willing to even consider due to your closed mindedness on the subject. In a further effort I'll just ask you why brakes get hot even in a single panic stop. Could it be friction? Could that be friction of the rotor sliding against the pad for a small amount of time? How could that be if the clamping (stopping) of the wheel is instananeous?

But never mind. You never answer any of the questions if they don't fit your model of how the system works. It's like trying to reason with a mule. First you gotta get their attention.

[Knightshade]

You haven't explained a single thing.

You just keep insisting you're right despite every expert on the topic saying you're completely wrong and every single test done proving it.

The caliper provides a clamping force, this force is applied (instantly) to the pads which translate that force, modified by the pads CoE, to the rotors.

Time is not a factor there.

That force, in the "one panic stop" scenario we're discussing, will exceed the force required to engage the ABS system. All of that force, beyond the traction/friction limits of the tires, is wasted force.

So if the CoE is high enough to engage the ABS system then a pad with a higher CoE will do NOTHING to stop the car any fast. It can't.

You've in no way explained how it possibly could anywhere in the thread. You just keep insisting that somehow one pad does it faster than another, which is physically impossible in this scenario.

[bartkat]

So much for trying to write so you can understand. Your asking others for support of your position, most not in total agreement, some trying to help explain things to you, indicate that you aren't as secure in your belief as you would like us to think. You continue to ignore some factors involved and as long as you do this, there's no use in trying to convince you of anything. I'll now close this thread and leave it here for posterity.