Brake Pad Dust Issue

[smooth1]

It's not a hydraulic system, but it's a system that improves the relationship between the pad and the rotor, not the tires and the road. So taking that into account, then there is room for improvement in the rotor and pad friction design then right? I mean they are still using both. And although I can't find it now, and I wasn't going to say it till I did find it, I thought I might mention that 2 of his 40 patents are a new pad design that maintains a higher friction capacity which was used in those tests to get that shorter distance. It did not say that the pads themselves were a contributing factor or not, but I think then why did he invent them or patent them as part of his new design?

I guess I am of the opinion that many scientist and engineers have come along and said "This is the law..." only to be overidden by new technology and a new scientist later. Nothing is ever absolute. Especially when it comes to such a diversified and complex physics nightmare like the car. There are so many acting and overriding laws of physics being applied at so many different stages of every act. take braking for example.......You did erroniuosly mention, or post an article with some now infamous scientist which stated that brakes tranfer mechanical energy into heat energy. That is not right. You can lock up the brakes, which will stop the car, and not produce any heat on the rotors or pads. You are transferring mechanical energy to the ground. The tires are doing that part, not the rotors.

So I think you were both right. I know that sounds like a cop out, but in truth, you both were. The adhesion limits of the tire do in fact limit the braking ability. I think Bartkat, and myself included are just not convinced that we have acheived a system that effectively maiximizes the limits of those tires yet. There is still room for improvement.

[Knightshade]

It's not a hydraulic system, but it's a system that improves the relationship between the pad and the rotor, not the tires and the road. So taking that into account, then there is room for improvement in the rotor and pad friction design then right? I mean they are still using both. And although I can't find it now, and I wasn't going to say it till I did find it, I thought I might mention that 2 of his 40 patents are a new pad design that maintains a higher friction capacity which was used in those tests to get that shorter distance. It did not say that the pads themselves were a contributing factor or not, but I think then why did he invent them or patent them as part of his new design?

I guess I am of the opinion that many scientist and engineers have come along and said "This is the law..." only to be overidden by new technology and a new scientist later. Nothing is ever absolute. Especially when it comes to such a diversified and complex physics nightmare like the car. There are so many acting and overriding laws of physics being applied at so many different stages of every act. take braking for example.......You did erroniuosly mention, or post an article with some now infamous scientist which stated that brakes tranfer mechanical energy into heat energy. That is not right. You can lock up the brakes, which will stop the car, and not produce any heat on the rotors or pads. You are transferring mechanical energy to the ground. The tires are doing that part, not the rotors.

So I think you were both right. I know that sounds like a cop out, but in truth, you both were. The adhesion limits of the tire do in fact limit the braking ability. I think Bartkat, and myself included are just not convinced that we have acheived a system that effectively maiximizes the limits of those tires yet. There is still room for improvement.

Yes, that is a cop out.

Since we weren't talking about what possible future systems might do.

We were talking about what the CURRENT system on the 2IS can do.

Will you please answer the actual question being asked?

As to the wedge system, again, it's a -completely- different system. It uses a pad, but the system around the pad isn't anything like the kind used on virtually every vehicle in the world today. It'd be like asking why certain mods for a gasoline engine don't respond exactly the same way when done on a diesel engine...I mean both make a car go, so they MUST be the same, right? Not exactly.

All the discussion that has occured thusfar is about modern hydraulic braking systems, where the pad doesn't matter for a panic stop so long as it can engage ABS.

If my suggested reverse rocket system somehow incorporated a pad that changed thrust of the rockets that would impact braking distance too, but it'd still have nothing to do with what was actually being discussed.

So again I ask, concerning the -actual topic- who was correct?

If you're saying I am correct about what we're actually talking about, and Barkat might possibly be correct some day n the future when they completely change way brakes work then please say that.

Right now it just sounds like you're trying not to hurt his feelings... which is commendable, but it'd be nice if people reading thie thread in the future had a clear enough picture of how things actually work on their actual cars, not some theoretical future having no current relevance to the 2IS. That's part of why I've tried to provide so many sources verifying my info, including the folks who designed both the IS-F and F-sport braking systems.

[smooth1]

I understand your wanting to make your point, especially after beating on the huge drum for so many pages.

The brakes don't stop the car. So long as the pads provide sufficient friction to engage the ABS system different pads can't change braking distance for a given stop.

This was your first statement. You stated here "given" stop, not Full out braking distance panic stop or 60-0 best performance stop. Any given stop. then later you said:

But certainly if you're applying well UNDER the amount of pressure that would engage ABS then different pads (as well as other things) could change the distance it would take the car to stop given a fixed pedal input.

You yourself typed that. So up to the point of ABS kicking in, there is room for improved braking, be it the pads, the rotors, or the system that incorperate those. And the EWB system proves that.

I know you think my examples are not relavant, but I'll try again, if you put a 36 lbs tire in the air and spun it up to 60 mph, and applied a brake to the tire, it wouldn't stop imediately with 1 lb of pressure. It would take a huge amount of clamping force just to overcome the energy built up. Add to that the load the car is putting on the tire, and you have almost 3 tons of spinning force that as to be broken before the traction issues even come into play. The fact is that ABS systems are not designed to acheive the shortest stopping distance, they are designed to create a controlled stopping distance. the new EWB is a system that is designed to use the maximum grip available by BOTH the pad and rotor, and the tire and road. the fact that the system targets the pad and the rotor clearly indicates that the hydraulic system used for braking today STILL DOES NOT ACHEIVE THE SHORTEST STOPPING DISTANCES. If your reverse rocket theroy makes the pad and rotor relationship stop the car in a shorter distance, then it is relavant, as the friction between the pad and the rotor are the stopping force for the tire. going back to my Dragster comparison, we have tons of HP that can easily break and over run the tires, yet, we have learned that by applying light throttle and waiting for momentum to be created can help us apply additional throttle and more power as we go. Thus creating huge amounts of acceleration along the way. Simply saying that the accelleration is limited to the traction ability of the tires is, well, like an understatement, or over simplified. Theres ALOT of dynamics that come into play to completely understand that statement. Take the IS 350. It can accellerate 0-60 in under 6 seconds with 306 hp, but to going from 60-120 in that same amount of time would take a sick (although desireable ) amount of HP! the same is true for braking, only in reverse. there is alot more to stopping in the shortest amount of distance than that.

I'm not going to get into the semantics of right and wrong here. I think we are beyond that, and keeping the forum in persective, I will repeat myself. THE ADHESION ABILITY OF THE TIRES LIMIT THE ENTIRE PERFORMANCE ABILITY OF THE CAR, CORNERING, ACCELERATING AND BRAKING. But there is still room for improvemetns in all aspects within the limits of the tires. ABS can still be improved and offer shorter stopping distances. The grip of the tires can be further manipulated and controlled by improving components in the braking system, wether that be the pad, the rotor, or the system that operates them. Improvements in suspension and weight distribution can further improve acceleration abilities, and effective cornering, all within the limits of the tires.

[Knightshade]

Yes, I said the pads can change the distance under the ABS threshold for a given unchanging pedal pressure.

I then added (and you failed to quote) that either set of pads can stop in the -same- distance, it would just require a different amount of pedal effort.

So the pads aren't changing the distance the car is -capable- of stopping in, they're just changing the feel of the system (it requiring more or less pedal pressure for the same result). Which I mentioned from the very begining (feel) as one of the things pads CAN change.

We aren't discussing top fuel racer acceleration though, nor wedge braking systems that don't exist on our current cars and use a completely different system (no brake fluid even). Likewise we're not discussing jet packs strapped to the cars and actuated with a pad/rotor combo in some way.

Let me ask you a direct question, since you seem to want to dance around anything resembling a direct answer by throwing up crazy scenarios-

Yes, or no- Can different pads (that can both engage the ABS system properly) on the -existing braking system on an IS350- change the stopping distance of a single panic stop on not-overheated brakes. Yes, or no?

Barkat insists yes. I know it's no.

Which is it?

(and if yes, please explain how, without invoking any parts or technologies that aren't actually on the car)

[smooth1]

It's a trick question! the pads in that scenario are not the controlling force, it's the ABS system that controls the braking based on the information coming from the speed sensors monitoring the tires. The scientist, and you are correct in that in the ABS system, the pads don't matter, as the ABS system dictates the distance needed for stopping. But if they came out with a pad and rotor combination that could achieve tires threshold of adhesion without going over, then we wouldn't need an ABS system!!

[smooth1]

So the pads aren't changing the distance the car is -capable- of stopping in, they're just changing the feel of the system (it requiring more or less pedal pressure for the same result). Which I mentioned from the very begining (feel) as one of the things pads CAN change.

This is pure conjector semantics btw! If 250lbs of pressure on a pad/rotor combination stops a car in 60 feet from 40 mph without engaging the ABS system, and you changed only the pad and stopped in 55 feet from the same speed with the same brake pressure, the pad created a shorter stopping distance. Period.

[Knightshade]

No, the car didn't create a shorter stopping distance BTW... stopping distance isn't measure based on partial pressure braking. We went over that pages ago. The car with either pad can comfortably stop in 55 feet, just with differing pedal input. As PF explains changing your pad doesn't change braking distance, but it CAN change the feel of the system (ie amount of pedal input needed for a given force, but you'll still generate that force with either pad just with differing inputs)... It can even stop in less distance that that, an indentical distance with either pad, if you mash the brake pedal. You know, the panic stop.

THE ACTUAL TOPIC OF THE THREAD.

[Knightshade]

It's a trick question! the pads in that scenario are not the controlling force, it's the ABS system that controls the braking based on the information coming from the speed sensors monitoring the tires. The scientist, and you are correct in that in the ABS system, the pads don't matter, as the ABS system dictates the distance needed for stopping. But if they came out with a pad and rotor combination that could achieve tires threshold of adhesion without going over, then we wouldn't need an ABS system!!

I'm not sure how it's a trick question. It's a simple question based on the actual situation that exists.

And somewhere in there you actually admitted I was correct and Barkat was wrong... thank you.

even if you had to add "If someone invented something totally different from what exists now, the answer would change!" one more time :P

[smooth1]

No, the actual topic of the thread was about brake dust. Then someone mentioned they felt a difference in stopping distances, and you made it this thread about 1 specific scenario regarding total stopping distance in an ABS situation. Your the only one who has spoken of that.

[Knightshade]

No, the actual topic of the thread was about brake dust. Then someone mentioned they felt a difference in stopping distances, and you made it this thread about 1 specific scenario regarding total stopping distance in an ABS situation. Your the only one who has spoken of that.

No I'm not.

It was barkat who wrote the "one panic stop" post.

Brake pads don't reduce stopping distance under any braking scenario though, if you define braking distance honestly. (and don't bring in completely different braking systems having no relevance to the 2IS of course)

Braking distance- the minimum distance in which a vehicle is capable of making a single stop at a given speed.

This is generally tested/measured by car makers, car magazines, etc by slamming the brake pedal to achieve maximum force and most commonly tested from 60 or 100 mph.

Change the pads all you want, the car will still be capable of stopping in the same distance. You can certainly use less pedal pressure and get -longer- distances, and those longer distances might see variance in pedal pressure required for a given distance depending on the pad. But you won't see any shorter ones.

Likewise if you're making repeated high-speed stops in a short period of time (ie- racing for example) you could well see -longer- distances sooner than later depending on the pad you use as some will begin to fade before others. But no pad will make them -shorter- they will just keep them from getting longer for a few extra stops.

[CrunchySkippy]

...the pads in that scenario are not the controlling force, it's the ABS system that controls the braking based on the information coming from the speed sensors monitoring the tires.

I think that's the answer. And it clearly states the assumption that the debate scenarios are utilizing the same ABS system.

By the way, I'm still very happy with the reduced dust!

[bartkat]

Anybody got comparative data on those stopping distance claims?

[smooth1]

Look, I'm over this already. Your applying one braking test results to all braking applications, and that's not correct. They measure that way so as to compare one car to another, not one braking system to another. And actually even in ABS systems, that measurement form car to car is more of a gauge used to judge other componenets of the car such as suspension, vehicle weight, and the distribution of that weight. I mean come on, if what your saying is true in all cases of braking, then they could just take the size of the contact patch, the weight and speed of the car and tell you how long the braking distance is, yet that formula never translates to the actual stopping distances as the rate of decelleration is not a constant. Hence my question about the raised truck and the Lambo. If everything is equal in the brakes sytem, pads, and tires, and the ABS system, the Lambo will have a better stopping distance than the truck because 1, the trucks center of gravity is much higher, and the weight bias is already all at the front of the truck, so in that case, considering both cars have the exact same tires, also, the braking distance isn't determined by the ABS system, the tires or the pads, it's determined by the inertia and the trucks poor design. You keep leaving out the time it takes to get to lock up. And the ability to maximize that time. The only thing the braking distance in an ABS panic stop demonstrates is how well the ABS system brakes the car during a panic stop. In all other cases, the ABS system doesn't engage, so the pads, rotor, fluid, all matter then, as they all effect the amount of force needed on the pedal to produce a stop. take a 15 mph panic stop for example, no ABS required, the amount of force pushed on the pedal clamps the pistons on the pads that grip the rotors and bring the car to the quickest stop capable within the limits of the tires. No ABS needed. Are you still certian that changing the pads to a higher friction won't slow the car any faster? Going in the opposite diection, while changing my tires to a softer compound would help make my car faster, but only if when I touched the gas pedal it created instant wheel spin and I couldn't get any traction as the throttle simply over powers the tires. BUt my car doesn't have anywhere near that amount of HP. Yet I can still spin the tires right now! And if I put 50 more hp under the hood, and translated that to a higher usable torque curve, I would still be faster with the same exact tires! Again, room for improvements way before I have exceeded the limitations of the tires! Even in an ABS system, improving the suspension could improve braking distances in a 60-0 panic stop, but would offer little help in a slower, less dynamic braking situation where the weight of the car is still fully maintained.

[Knightshade]

Anybody got comparative data on those stopping distance claims?

Yes, as I posted like 4 pages ago. Someone testing with both sets of pads and found identical distances.

Because physics requires that to be the case.

Just like me, the ABS engineer, Brembo, Stoptech, and now even Smooth1 have told you.

You're the only person involved who still doesn't understand how brakes work or why you were wrong in what you wrote in your "one panic stop" post.

[Knightshade]

Look, I'm over this already. Your applying one braking test results to all braking applications, and that's not correct. They measure that way so as to compare one car to another, not one braking system to another. And actually even in ABS systems, that measurement form car to car is more of a gauge used to judge other componenets of the car such as suspension, vehicle weight, and the distribution of that weight. I mean come on, if what your saying is true in all cases of braking, then they could just take the size of the contact patch, the weight and speed of the car and tell you how long the braking distance is, yet that formula never translates to the actual stopping distances as the rate of decelleration is not a constant. Hence my question about the raised truck and the Lambo. If everything is equal in the brakes sytem, pads, and tires, and the ABS system, the Lambo will have a better stopping distance than the truck because 1, the trucks center of gravity is much higher, and the weight bias is already all at the front of the truck, so in that case, considering both cars have the exact same tires, also, the braking distance isn't determined by the ABS system, the tires or the pads, it's determined by the inertia and the trucks poor design. You keep leaving out the time it takes to get to lock up. And the ability to maximize that time. The only thing the braking distance in an ABS panic stop demonstrates is how well the ABS system brakes the car during a panic stop. In all other cases, the ABS system doesn't engage, so the pads, rotor, fluid, all matter then, as they all effect the amount of force needed on the pedal to produce a stop. take a 15 mph panic stop for example, no ABS required, the amount of force pushed on the pedal clamps the pistons on the pads that grip the rotors and bring the car to the quickest stop capable within the limits of the tires. No ABS needed. Are you still certian that changing the pads to a higher friction won't slow the car any faster? Going in the opposite diection, while changing my tires to a softer compound would help make my car faster, but only if when I touched the gas pedal it created instant wheel spin and I couldn't get any traction as the throttle simply over powers the tires. BUt my car doesn't have anywhere near that amount of HP. Yet I can still spin the tires right now! And if I put 50 more hp under the hood, and translated that to a higher usable torque curve, I would still be faster with the same exact tires! Again, room for improvements way before I have exceeded the limitations of the tires! Even in an ABS system, improving the suspension could improve braking distances in a 60-0 panic stop, but would offer little help in a slower, less dynamic braking situation where the weight of the car is still fully maintained.

Again, you keep trying to offer completely unrelated comparisons.

A Lambo vs. a Truck? Huh?

How about a lambo vs. a lambo.

Or a truck vs. a truck?

Now change the brake pads.

Did stopping distance (as previously defined) decrease? Nope.

It can't.

Pedal effort required might change, but you won't be able to stop the car any shorter than you could with the other pads.

From 15 mph or 60 mph, or 100 mph that will remain true.

[Knightshade]

In all other cases, the ABS system doesn't engage, so the pads, rotor, fluid, all matter then, as they all effect the amount of force needed on the pedal to produce a stop.

There's a key point right there even if you don't realize you made it.

Yup, all those things can change how hard you need to push the pedal to stop the car.

None of them can change the distance in which the car is capable of stopping though.

They're two entirely different things.

Unless you have some kinda muscle problem where you can't push the pedal normally I guess... then it might matter.

[bartkat]

I've seen no data from a controlled test presented here.

[Knightshade]

I've seen no data from a controlled test presented here.

No, you saw a link to the thread where it was described instead.

You also saw half a dozen experts on braking systems (including two companies WHO DESIGN BRAKES FOR LEXUS) telling anyone who can read english that it's impossible for brake pads to reduce stopping distance. Most certainly not in the "one panic stop" situation you claimed it did.

You're literally the ONLY person here who thinks otherwise at this point. Apparently only because you're incapable of admitting you're wrong.

[bartkat]

Any reports from brake companies, brake sales, etc are invalid since they are only trying to sell you brakes, per knighshade.

A test by some guy on some message board, no matter how unscientific is gospel.

That's the way it is.

[Knightshade]

Seriously, what's your deal exactly?

The folks who built the brake system on the IS-F say you're wrong.

The folks who built the F-sport brakes say you're wrong.

Me, all the tech guys at CL, Smooth1, Gaugster, and everyone else who has posted in this thread either way all say you're wrong.

The guy who designs ABS systems for a living and has literally written books on braking systems says you're wrong.

The guy who actually tested the two pads in question say you're wrong.

And you just keep sticking your fingers in your ears and jumping up and down insisting it just isn't true while tossing out groundless accusations of dishonesty and misquoting. with absolutely zero to back any of it up except a glaring ignorance of what brake pads actually do.

[bartkat]

If one totally ignores the distance the car travels from when the pads first engage the disks till the time the wheel stops turning, then braking distance totally depends on tire adhesion in a single panic stop. However, that distance cannot be ignored. If, a mighty big word.

[Knightshade]

If one totally ignores the distance the car travels from when the pads first engage the disks till the time the wheel stops turning, then braking distance totally depends on tire adhesion in a single panic stop. However, that distance cannot be ignored. If, a mighty big word.

I don't even know what you're trying to say there. Neither do you I suspect.

Once again, "time" does not appear as a variable in any equation related to braking force.

The amount of time it takes the -entire- brake system to go from "not stopping at all" to "ABS fully engaged" is milliseconds...

You seem to keep thinking the pads have -anything- to do with directly stopping the wheels, and they don't. They're not even directly connected to the wheels, the rotors are.

The -only- thing the pads do is translate the clamping force of the caliper into frictional force to the rotor. This happens instantly.

Multiply the clamping force by the CoE of the pad, and that's the force on the rotor. Instantly.

As long as the CoE is high enough to produce enough force to engage ABS the car will stop in EXACTLY the same distance as with any other pad that can engage ABS.

It's really pretty simple math that everyone else involved understands and you seem to completely not grasp.

[JENunnez]

Hhmmm, Yeah, so I've been reading up on this thread and thought I would of course put in a few words.

I can't take it anymore. LOL!!

Knightshade, I have to say, in my opinion, your just not qualified to read those articles.

If all tires being equal determine the stopping distance and not the components, then how do you explain why my car can out accelerate other cars with the same tires? I mean, the road force friction being the only thing that stops a car is also the only friction that causes a car to accelerate also right? If both cars have enouph HP to cause the tires to break loose, then the amount of horsepower and torque become irrelevant then? Do I have to post a video of my car out accelerating other cars for that fact to be reinforced or are we on the same page with that? OK. Good.

So, let's go back to the article you posted for a moment. His article on the chalk board is correct. The maximum amount of braking distance is going to be limited by the friction between the tires and the road. We all know that. That's a big "Duh!" in my book. But that friction and grip relationship between the road and the tires can be manipulated and changed with suspension set up, and break force distribution. (Putting more braking force to the front rotors than the back for example.) And also breaking input and technique applied by the driver can have a huge impact on the stopping distances. My point here is, Let's suppose a Top Fuel Dragster is capable of quarter mile times of 4 seconds. Do you think you could hop in one and produce 4 second quarter mile times? Regularly? No, probably not. In fact, you wouldn't even come close. So the maximum friction numbers never come into play then do they? That is the point of his article. It's not like you drive around town using maximum acceleration and then apply maximum braking forces to stop the car regularly, therefore testing the limits of all the components.

My dad was brought in to help supervise and consult with the NLECTC back in 1996-2000 regarding this very issue for the National Institute of Justice.

NLECTC Report

The problem was that everyone was using different and sometimes "cheap" brake pads on their protol cruisers. And it was becoming a huge problem. So they put together a board to evalutate break pad performances for thier cruisers and then put together a model recommendation listing for brake pads. Like the Crown Vics were found to be better with a certian brake pad and the Chevy Malibu's were fitted with a different pad that worked better for it also. To say that the pads don't change braking distances is ridiculious because of the ABS systems, not despite them.

Heres another test : Ford Club Brake Pad Testing That is from the Ford Muscle that my dad frequents and again helped to put that article together. ( He races Mustangs......alot of em!) LOL!! I can assure you all they did was replace the pads.

I know what you think your reading there, but I promise you, I have myself replaced and upgraded entire braking systems to race ready levels and beyond, and we used the same tires we have always used and the before and after braking distances aren't even close!!!!! I've taken 80-90 ft off stopping distances plus, and greatly improved thier hot performances in some very harsh environments. Like giving a car to a rookie driver on the track is probably the worst and hardest conditions you can subject to a braking system. And after those races, usually only 10 laps on a 1/2 mile track, it's the pads being replaced for the next race, not the tires at that point.

Smooth here is the complete pdf of the NLECTC Report with the graphs showing panic stops with abs.

Sorry Knightshade but pads do make a difference, even with abs.

EvaluationBrakePads2000.pdf

[Knightshade]

Did you actually -read- the report you just posted?

Here's a quote from it:

"When braking to a targeted deceleration rate, where the speed of the vehicle at brake application is the same, the stopping distance should also theoretically be the same, making any measurement of stopping distances irrelevant"

You OWN SOURCE agrees that stopping distances will be the same all else being equal.

This appears right after they explain why they changed their testing methods from the last time, because they concluded the panic stop testing wasn't as important as "comparing pedal effort"

All of this appears on page 4 of the report.

They then show several pages of results showing pads change the pedal effort. Which I've been telling you the whole thread.

Then they explain they tested panic stop distances -after- heating up the brakes with other tests. Which is exactly NOT the situation described in the entire thread on how to test a panic stop. Which means their results weren't showing stopping distance at all. They were showing resistance to fade due to heat. An issue I also discussed since early in the thread.

So what your source -actually says- is:

Pads don't change optimal stopping distance

Pads DO change pedal feel

Pads DO change how resistant to fade the brakes are.

Which are 3 of the points I've been telling you since like page 2 of the thread.

Seriously, why post a source you didn't bother to read or understand?

[terry993]

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.