is-eF

Hmmm...good point!
That would mean the Camry is a High Performance car too! After all they are in NASCAR, as well as the Tundra!
I see your point, but the op was talking about dust build up on a daily driver car, not a race car. Should the isf ever be a full time track car it will be a totally different car than what we are driving on the street.
Marketing is just that...marketing to get people like us to purchase the car.
Just trying to keep this with what the op asked.
Enough said on my part as I feel I'm wasting my time.

TherealFIG

wow this thread when downhill fast.

PHXDiesel

Ahh a sad response. Please point out where I mentioned "racing" aside from the description "ricky racer"? If you brake hard enough, you get the same result. You don't have to be racing. I'm very sure you watch a mile into the distance and coast to a stop, and no one _ever_ cuts you off on the freeway. Your pads should last 150k miles!

I'll ignore the rest of the inept comments. Have a nice day.

larrysb

Actually, the composition of the pad *DOES* affect stopping distance. If they all worked equally well, there'd only be one kind of brake pad.

Many racing application pad compounds are designed for high operating temperatures. They provide great resistance to fade under track conditions (the kind that make rotors glow cherry red). Typically, these pads are likewise unsuitable for street use because they do not have good stopping power when the pads are cold.

I've personally driven cold racing brakes that you literally had to stand on the pedal to any stopping power out of them.

Then at the other end of the extreme, there are low-cost replacement parts market pads for street cars. These pads are made for cheapness and nothing else.

OEM pads are usually designed to provide good stopping power at low temperatures, low noise and of course, low cost. Sometimes, they consider dusting. Usually not.

Sports cars often have very different OEM compounds than their similar non-sport versions. For instance, the Corvette C5 Z06 used a different part number pad than the Coupe and Convertible models. They made more noise and they dusted a great deal more, but test after test indicated that they had better cold and hot stopping characteristics than the original formulations and were suitable for track-day operation. As an aftermarket part, GM also offered ceramic formulation pads for the C5 Corvette - which dusted much less and quiet operation, but test after test showed a small but repeatable reduction in stopping distance. They were all physically interchangeable GM parts, but had different stopping, nose and dusting characteristics.

Clearly, the pads on the ISF fall in to the same slot as the Z06 pads mentioned above. They are dusty. They make noise. But they have more aggressive characteristics. Every review of the brakes has been excellent and mentioned no-fade operation on the track. Lexus' own literature states clearly that the high friction pads on the ISF may experience shorter than expected life.

But on the upside, if they aren't "weird", one big advantage of Brembo is they're very easy to change pads.

The pads will need to be changed often. Just comes with the territory.

I do think, many ISF owners would be happier with ceramic pads.

chikken

why don't you guys just downshift and not press the brakes so hard, maybe that'll reduce the brake dust...

lx470man

iTrader: (1)

so has anyone changed thier pads for lower dusting pads? cause i dont think all this dust is nessary for me for the kind of driving i do everyday for street use.

LEXUSF

iTrader: (3)

wow you drive alot. thats gonna suck on brakes and tires.

CaThaFeR

iTrader: (1)

brakes yes.. tires no

im up at 21,700 now

gshb

I wont go too much into this, but lets try not to be holier than thou just because you have a supra and was in the airforce .

There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction. In general, all pads display a bit of each, with abrasive mechanisms dominating the lower temperature ranges while adherent mechanisms come more into play as pad temperature increases. Both mechanisms allow for friction or the conversion of Kinetic energy to Thermal energy, which is the function of a brake system, by the breaking of molecular bonds in vastly different ways.

The abrasive mechanism generates friction or energy conversion by the mechanical rubbing of the brake pad material directly on the rotor disc. In a crystalline sense, the weaker of the bonds in the two different materials is broken. This obviously results in mechanical wear of both the pad and the rotor. Consequently, both pads and rotors are replaced when they are physically worn to their limit and are too thin to endure further service.

Different brake pads have differing compositions, depending on their intended duties. As such, they will have differing bond energies that directly correlate to stopping distance. Heat build up drives the braking power limitations. If one wants more braking power you need more thermal mass in the brakes. Ceramic pads (that is to say, a pad with inorganic compounds), in general, provide shorter stopping distances than semi-metallic pads.

I would elaborate, but this should be sufficient for a basic understanding. Tires are a function as well since they are a function of the kinetic friction formula, but unless all brake pads are just awesome, brake pads will reach their thermal threshold before a tire will.

As for just regular street driving, then its kind of obvious. You dont even need the nice BBK on the ISF if you never intend to use the car for its intended duties (read: high performance driving).

Edit: I will concede your half truth.

LEXUSF

iTrader: (3)

I can get you a deal on factory parts if you need! :d

chikken

do you know if they came out with ceramic pads for the is-f?

lobuxracer

iTrader: (2)

And I will ask your profession. Since Pulp Friction was written by a guy who has forgot more than both of us have ever known about braking systems, why would he say pad selection has no bearing on stopping the car? Wait. If I GREASE the pads, then yes, it will be worse. But if the pads generate sufficient friction to engage ABS, then your pad friction argument is moot and its all about the tire/road interface. I have yet to see a pad released to the public in modern times incapable of engaging ABS, therefore, argument = moot.

So discussing the types of friction and casually throwing out that some pads create shorter stopping distances when a Graduate Brake Engineer who's been working in the industry for both street and competition braking systems says it doesn't matter, sounds like BS.

Do you really have the credentials to call this guy a liar?

LexISguy

I might update my pads.....

GSteg

iTrader: (15)

LOL @ pads reducing stopping distance. I also laugh at those who think adding on bigger brake kits will reduce braking distance. If the OEM setup is powerful enough to lock up the wheels, what better is it to have more braking force?

Pads do improve braking performance, however I will say that for me, performance is a combination of many factors including fade resistance. As long as there is some kind of improvement, I consider it an improvement in performance. It's like judging a car's performance. Performance isn't just straight line speed. It's the overall picture: speed, braking, handling, etc.

So for me, there is an improved performance with different pads, but I dont expect it to reduce my braking distance any more than the OEM pads. You would have to have some magical pads to increase your tire's traction

gshb

Stop being such a sensationalist. Im not the one dying of laughter and belittling other people. You cant just generalize an environment with multiple systems with specific boundaries for your case. Its obvious I have to break it down for you since you dont understand all of my assumptions.

1.) That the car is equipped with ABS. Yes, modern cars have brakes that perform well enough to engage ABS. But not all do, both road going and especially race cars. On a dry surface, ABS will still be engaged so that the tires static coefficient of friction comes into play and not the tires kinetic coefficient of friction, which is smaller. Like I said before, the brakes will reach their thermal threshold well before a tire will. So, your tires are not going to destroy themselves from simple high speed brake tests. But, there is yet to be a system that, like ABS, actively controls operating temperature of brake systems to maintain its highest coefficient of friction. Here is a link showing how an aftermarket Stoptech brake system performed a little bit better than standard pads: http://www.sportcompactcarweb.com/ro...est/index.html

However, the point was that the aftermarket system was more consistent. They also made the assumption that pad friction coefficients were the same (to draw some conclusions). This is actually the crux of the argument, in the end its about coefficients of friction from tire to road and rotor to pad.
2.) That the sampling for data is more than just one run. You can read up on statistical analysis and why reading only a few runs doesnt give you any information. http://home.ubalt.edu/ntsbarsh/stat-...pics.htm#rwisd
3.) Finally, given this is a high performance car, we would assume the driver will be fully utilizing the car on road or track. You dont just brake once on a track.

As temperature increases in the pad lining, coefficient of friction will decrease beyond the operating temperature. Different materials have not only different coefficients of friction, but also thermal capacitance. There are a few studies to show different materials at different temperatures, showing the coefficient of friction. I have some study links below, since my books do not have these graphs for any materials (they are old). This is why some pads have differing compositions of Cu, Al, and steel. When the coefficient decreases, the amount of force the pad is able to generate (all else being equal) is much reduced.

Here is a paragraph from Pulp Friction, "Brake pads with radical changes in coefficient over their operating range are not a racer's best friend. Be sure to select one that remains relatively stable under the operating conditions you are expecting, but don't expect any shorter stopping distances, because the brake pads don't stop the car!" This sounds oxymoronic. On the one hand, brake pads dont change stopping distances. Yet on the other hand he says choose a pad that has a stable coefficient over a some window of operating temperature. Well which is it? If changing the pad makes no difference, then why bother? If the coefficient changes, rotor torque changes and thus the time it takes to stop changes (all else being equal)!

If you were to slap on some racing pads and went to town, you would notice a need to increase pedal force to obtain the same stopping force compared to regular pads. Likewise with ceramic pads. But being good engineers, you dont just do one run and conclude that ceramics and racing pads are worse than your vanilla pads.

Coefficient of friction from the tire to the road ranges between 0.6 and 0.8. If we were to assume same brake pads, can we predict that stopping distances will change if we used different tires? Yes. We know civilian tires have lower coefficients than an R compound tire. But why? Is it the tread (or lack thereof)? No. Is it the size of the tire? No. Its composition.

Without brake pads your car will not stop. Ok, now Im being sensational, but if tire composition affects braking distances, then brake pad composition (which provides us the opposing force) should as well. Most vanilla pads will have a coefficient of friction from 0.3 to 0.4. Racing pads have a higher coefficient in their operating temperatures, ranging from 0.4 to 0.5 or even higher for the state of the art ceramics (silicon carbides, http://www.edmunds.com/ownership/tec...3/article.html). Higher performance pads will maintain their stopping distances for longer than vanilla pads. Why does every car mag bother to do braking tests beyond the first one? Because brake pads arent just used once, they are used multiple times and pad compositions determine how many times or how long they can give you certain stopping distances.

In the end my point is you cant ignore any system for a complex environment such as this. This is why some people can devote their entire careers to just brake systems (James Walker). But obviously its not so simple to say pad materials have no effect on brake distances. Theres tons of research being done by engineering companies and auto makers and a brief explanation of the results can be read here, the Formula 1 website:

http://www.formula1.com/inside_f1/un...port/5284.html

Pulp Friction reads like a magazine article. I would think his book does better in explaining every aspect of brake systems and Im willing to bet that pad composition gets a lot more words than just a few paragraphs.

More studies relating to pad materials and their effects on brake systems:

http://www.sciencedirect.com/science...47f99f0a46fe7b

http://www.sciencedirect.com/science...73a3236e74feaa