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Okay, so Dogzilla and I were discussing rotors and what not when I posed a question. Where do rotors really come from? What I mean is that most products come from a few sources and are just branded with different names. We know Nismo actually buys their stuff from someone else and puts their name on it. Food, gasoline, tools, they all come from a few select manufacturers or suppliers and then it gets distributed by another company with that name on it.

Are brakes and their components any different? People pay good money for great quality products such as Wilwood, Brembo, or Rotora. Do we know if those companies actually make their own products? Or do they have intelligent buyers who look for the best manufacturer with the highest stringent guidelines on producing a product? Well, we pretty much know off the bat that Brembo does make their own stuff.

Brembo currently operates in 3 continents with production plants in 10 countries; our commercial sites are based also in Sweden, France, and USA, while we sell our products in 70 Countries in the world.

At present, Brembo employees over 5300 people, nearly 10% of which are engineers and product specialists working in research and development.
So I asked if the standard rotors we see on most cars are quality parts that pass some kind of test? Yes they do. But what about the ebay stores that sell brands we've never heard or suspect are knockoffs? We're talking safety issues here, so I'm concerned about the fact that some people might buy the best deal and get something of a surprise when taking the fastest corner of a road course.

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Brakes 101

Anybody who works on brakes knows what brake rotors do. They provide a friction surface for the disc brake pads to rub against when the brakes are applied. The friction created by the pads rubbing against the rotor generates heat and brings the vehicle to a stop.

The underlying scientific principle here is that friction converts motion into heat, a LOT of heat! The amount of heat that is generated depends on the speed and weight of the vehicle, and how hard the brakes are applied.

A large, heavy vehicle, like a Chevy Suburban, will obviously generate more heat when braking than a Toyota Echo if both vehicles brake from the same speed. But the little Toyota may produce more heat than the big Suburban if the braking speeds are different, say 60 mph for the Toyota and 20 mph for the Suburban. Speed multiplies the effect of weight and creates momentum (also called "inertia" or "kinetic energy").
Brake horsepower defined or explained

Think of heat as a form of energy or power. A more familiar term is "horsepower." We all know what horsepower is, right? It is the stuff that spins the crankshaft when fuel is burned inside an engine. Combustion produces heat, and heat pushes the pistons that make the crankshaft go around. One horsepower is equal to 33,000 pounds-feet of torque per minute, or 550 pounds-feet per second.

We measure an engines horsepower output by hooking it up to a dyno and seeing how much force it can exert against the resistance created by the dyno. In effect, the dyno acts like a giant brake, so the engines power output is sometimes called its "brake" horsepower output.

By the same token, we can also measure how much horsepower a vehicles brakes must absorb when bringing the vehicle to a stop from a given speed. This is also called "brake" horsepower, but in this case it refers to the brake system, not the engine.

The brake systems on vehicles must be capable of absorbing a lot more horsepower than the engine typically produces because the heat (power) that is generated when braking occurs over a short period of time. Thus, a small car might only need 100 horsepower from the engine to accelerate from zero to a speed of 60 mph. If the driver slams on the brakes and comes to a screeching halt, the brakes have to absorb all the momentum in a much shorter period of time. This multiples the amount of horsepower that must be absorbed, as much as six times depending on the stopping distance. So a panic stop from 60 mph might require the brakes to absorb the equivalent of up to 600 horsepower!

Heat issues

The important point is the brakes often have to absorb a great deal of heat in a very short period of time.

How much heat, you ask? Using more math, units of horsepower can be converted into units of heat energy called BTUs (British Thermal Units). One BTU is the amount of heat it takes to raise one pound of water one degree Fahrenheit.

If you multiply horsepower by the proper conversion factor, you discover that one horsepower generates 42.4 BTUs of heat per minute. If stopping a 4,000 lb. vehicle from 60 mph in roughly 150 feet requires 600 horsepower of force, it is the equivalent of 25,440 BTUs of heat, which is enough heat to raise 15 gallons of water from zero degrees to boiling! No wonder the brakes get so hot.

One thing all brake manufacturers monitor very closely when testing and evaluating pads and rotors is the temperature of the brakes. Every time the brakes are applied, the pads and rotors generate heat that must be absorbed and dissipated. A quick stop from 60 mph can easily push the rotor temperature up 150 or more degrees. Several hard stops in quick succession can push brake temperatures into the 600, 700 or even 800 degree range. Remember, the heavier the vehicle, the more heat it creates when it brakes.

When brake temperatures get too high, the pads and rotors are no longer able to absorb any more heat and lose their ability to create any additional friction. As the driver presses harder and harder on the brake pedal, he feels less and less response from his overheated brakes. Eventually, he loses his brakes altogether.

All brakes will fade beyond a certain temperature. Semi-metallic linings can usually take more heat than nonasbestos organic or low-met linings. Vented rotors can dissipate heat more rapidly than nonvented solid rotors. Thus, high performance cars and heavier vehicles often have vented rotors and semi-metallic front brake pads to handle high brake temperatures. But if the brakes get hot enough, even the best ones will fade.

Rotors

Now that we have covered some of the physics of braking and the effects of friction and heat on the brake system, lets look at the rotors role in all of this. As we said earlier, the rotor's job is to provide a friction surface, and to absorb and dissipate heat.

Big rotors can obviously handle more heat than small rotors. But many cars today have downsized rotors to reduce weight. Consequently, the brakes run hotter and require better rotor cooling to keep brake temperatures within safe limits.
cross-drilled rotor

Anybody who works on brakes for a living knows that rotors can cause a lot of brake problems. Uneven rotor wear (which may be due to excessive rotor runout or rotor distortion) often produces variations in thickness that can be felt as pedal pulsations when the brakes are applied. The condition usually worsens as the rotors continue to wear, eventually requiring the rotors to be resurfaced or replaced.

Rotors can also develop hard spots that contribute to pedal pulsations and variations in thickness. Hard spots may be the result of poor quality castings or from excessive heat that causes changes in the metallurgy of the rotors. A sticky caliper or dragging brake may make the rotor run hot and increase the risk of hard spots forming. Hard spots can often be seen as discolored patches on the face of the rotor. Resurfacing the rotor is only a temporary fix because the hard spot usually extends well below the surface and usually returns as a pedal pulsation within a few thousand miles. That is why most brake experts replace rotors that have developed hard spots.

Cracks are another concern with rotors. Cracks can form as a result of poor metallurgy in the rotor (too hard and too brittle because the rotor was allowed to cool too quickly during the casting process), and from excessive heat. Some minor surface cracking is tolerable and can often be removed by resurfacing, but large cracks or deep cracks weaken the rotor and increase the risk of catastrophic failure. So cracked rotors should always be replaced.

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Okay, this is getting to be a long post and probably hard on the eyes. I'll pause here to let it sink in before I continue with the thread.
 

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Discussion Starter #2
BTW, I'm not actually writing all those definitions. :lol: I'm quoting a source. And we continue....

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Rotor DNA

The metallurgical properties of a rotor determines its strength, noise, wear and braking characteristics. The casting process must be carefully controlled to produce a high quality rotor. You cannot just dump molten iron into a mold and hope for the best. The rate at which the iron cools in the mold must be closely monitored to achieve the correct tensile strength, hardness and microstructure.

When iron cools, the carbon atoms that are mixed in with it form small flakes of graphite which help dampen and quiet noise. If the iron cools too quickly, the particles of graphite do not have as much time to form and are much smaller in size, which makes for a noisy rotor.

The rate of cooling also affects the hardness of a rotor. If a rotor is too hard, it will increase pad wear and noise. Hard rotors are also more likely to crack from thermal stress. If a rotor is too soft, it will wear too quickly and may wear unevenly increasing the risk of pedal pulsation and runout problems.

The composition of the iron must also be closely controlled during the casting process to keep out impurities that may form "inclusions" and hard spots. One rotor manufacturer says they sample the molten iron every 15 seconds to make sure the composition is correct. The molten metal is also poured through ceramic filters that trap contaminants. Even the sand that is used to make the molds is specially treated to control moisture content. This helps keep the sand in place and prevents core shifts that can affect porosity, dimensional accuracy and balance.

The grade of cast iron that is used in a rotor may even be changed to suit a particular application. One aftermarket rotor manufacturer uses a special grade of "dampened iron" to make replacement rotors for 1997-2002 Chevrolet Malibu and its sister vehicles (Olds Alero, Olds Cutlass and Pontiac Grand Am). In this case, the original OEM rotors turned out to be too noisy so General Motors switched to a dampened grade of iron to cure the problem.
Cooling ribs

Vehicle manufacturers use a wide variety of different cooling rib configurations in their rotors. They do this to optimize cooling for different vehicle applications. So even though the brakes may appear to be identical on two different models, one may require increased cooling because the vehicle is heavier, has a more powerful engine, has less airflow around the brakes, etc.

Some aftermarket rotor manufacturers use the same rib design and configuration as the OEM rotors, while others do not. Some change the rib design to simplify the casting process or to reduce the number of different rotor SKUs in their product lines.
rotor cooling

The OEMs currently use almost 70 different rib configurations in their rotors. Some ribs are straight, some are curved and some are even segmented. Some rotors are directional and some are not. Some rotors have evenly spaced ribs while others do not. Some ribs radiate outward from the center and others go every which way.

One reason why they use so many different rib patterns is to maximize cooling and to reduce harmonics that contribute to brake squeal. Changing the rib design changes the airflow, cooling and noise characteristics of the rotor, which may make things better or worse depending on the application. That is why some aftermarket rotor manufacturers use the same basic design as the original, while others stick with more traditional venting.

One brake manufacturer showed us a cutaway of an offshore "economy" rotor for a particular vehicle that had 32 ribs. The OEM rotor, by comparison, had 37 ribs and provided up to eight percent better cooling than the economy rotor when tested in the laboratory. And because the OEM rib design ran cooler, pad life was 28 percent longer than the economy rotor.

Another aftermarket brake manufacturer showed us test results that proved their rib design improves cooling and makes their rotor three times quieter than a competitive rotor. The recorded sound levels showed noise as high as 85 decibels screaming out of the Brand X economy rotor compared to only 40 to 50 decibels from their own "premium" quality rotor.


A heat dam is often machined into the area between the friction surface and hat on most rotors. The dam is a thinner section of metal that reduces heat transfer from the rotor surface to the hat. This protects the wheel hub and bearings from the heat and also allows the rotor to flex when it gets hot to reduce the risk of warping and cracking.

If a rotor manufacturer cuts corners and eliminates the heat dam, heat can travel more easily to the hub and wheel bearings and increase the risk of bearing failure. The rotor may also be more prone to cracking under high heat conditions.
 

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My suspicion is that when you buy Brembo, Stoptech, Wilwood, etc, you get product either made by, or specifically for those companies. They're major players, and stand to lose a lot if they have a faulty product. Because of this, they'll be more careful about the metallurgy of their rotors. The E-Bay specials however may not. These companies frequently buy rotor blanks and coat them, or drill them to get the effect that they want. This means you're buying parts of unknown quality, from an unknown manufacturer (which probably changes depending on who offers the lowest price), and are sold to you buy a manufacturer without much to lose, as many people will 'give the cheapest a try'. I'm all for trying the cheap bottle of wine, or the cheap body kit, but I want to know that when I need to panic stop, the rotor's aren't going to fail.

Like I posted in another thread, cross-drilled rotors can be a bad thing. Some manufacturers make their cross-drilled rotors by buying blanks and machining holes in. This is a very bad idea, as it can create stresses in the material (essentially cold working it), which can cause rotors to crack. The right way to manufacture cross-drilled rotors is to cast the holes into the blank, which creates even internal stresses, and reduces the risk of rotor failure.

Second to your tires, your brakes are your most important safety feature on the car. Without them, you lose critical control. There are many places where tradeoffs can be made, your brakes (rotors, pads, caliber, lines and fluid) should never be one of them. My recommendation would be to buy from well known manufacturers. If you don't I would suggest staying away from product made in China. While I haven't heard anything about their brakes, it's well known that they don't have the metallurgical knowledge (or don't practice it), that other countries do (machinists don't buy Chinese product for this reason). I'll let Dave expand, although I have other points I may jump in on. Sorry for the interruption Dave.
 

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Some myths and the truth about slotted and drilled rotors

There is a common fallacy out there that increasing your brake pad size in terms of swept area will increase the stopping power of your car through greater friction. From a standpoint ignoring operating temperatures this is in fact false. The force of friction is determined by physics as the force down on the object times the coefficient of friction. As such there is no surface area in the friction equation. However, the temperature of the pad varies throughout its use changing the coefficient of friction at each point along its temperature slope in a non-linear/non-progressive manner. As such it is possible that a larger pad will change the friction force favorably given pad makeup. It certainly will change the amount of time before the brakes enter the proper range and when they leave the range. It will also influence when and how long it is at the peak performance point. Meanwhile, modifying the pad material can change this operating range. As such the affect of increase in pad size on braking friction would depend on the makeup of the pad. Also note that the only way to modify the force down is to change the brake piston force (by size changes or number for example).
**disclaimer: I'm not a physicist, so I can't verify the above paragraph.

This does not mean that a larger brake pad does not help braking! The benefit of a large brake pad comes into effect when you consider thermal dissipation. The larger the pad the more this thermal temperature (created by the interaction between the pad and rotor) is spread amongst a pad. This means less temperature is concentrated at one point on the pad and the rotor absorbs more heat. This decreases the likelihood that the pad itself will heat beyond operating temperature. If the pad were to go beyond operating temperature it would glaze over resulting in brake fade. Furthermore, a larger pad results in a longer service life of the pad since there is more pad material to consume.
 

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Discussion Starter #5
CROSS DRILLED VERSUS SLOTTED ROTORS

The second thing you can do to improve your brake performance is often to go to a larger rotor. We all know that this gives the rotor further ability to dissipate heat away from the pads through itself and through the air (conductive and convective heat transfer). So obviously a larger pad, a larger rotor, or both result in better brake performance by avoiding brake fade.
ARGUMENT #2:

Cross Drilled Rotors have been considered by many professional race car drivers as a miracle product. Cross Drilled is the process by which Drilled holes are placed into unique areas of the Rotor which ultimately improves the quality of your brakes. When driving, stock Rotors can heat up to a very high degree and cause a failure to the brakes and to the Rotor itself. With the Cross Drilled design, your Rotors overpower the heat and keep the brakes in a newer and more reliable condition. Statistically through testing and research, these top quality Brakes have been established a 70% increase (opposed to stock Rotors) in intensive braking safety performance. This High Performance style has saved the lives of many drivers and brought contentment to many car-enthusiasts worldwide.


Slotted Rotors are the ultimate advantage to the concrete construction of Brake Rotors. Many Stock Rotors have a history and a tendency of cracking, bending, or just wearing out too quickly. With the Slotted option, the tendency of the Rotor has been known to endure a lifetime TWICE the amount of a Stock Brake Rotor. The Slotted design keeps the Rotors cool from the overheating gases and the excessive use of brakes. Not only has this option improved the performance of the Rotors but they have also improved the gripping functioning of the brakes when being pressed down on the Rotors. The flat OEM (Stock) surface of the Rotors makes it difficult for the brake pads to grasp on properly as opposed to the gripping of the Slotted Rotors which helps the brakes give the car a smoother and less enduring stop. Statistically, according to research and testing, the Slotted Design has a 40% more efficient and safer braking distance than stock Rotors.

Slotted rotors, have engraved indented lines in the brake rotors. When you brake, the Brembo brake rotors grip on to the brake pad much better. Regular rotors have a smooth surface, while breaking it does not allow the pad to grip onto anything resulting in less braking performance. Slotted rotors improve the braking distance by 40% then a regular OEM (Original Equipment Manufactures) rotor.
For maximum braking performance it is recommended to get both cross drilled rotors and slotted. If you plan to race the car at tracks, we would recommend you to get only slotted rotors since too much racing and extreme braking may result in the rotor building too much heat and cracking. It will only result under extreme conditions. If don't drive recklessly and only race once in a while it will not affect you. It will only affect you if you race on the track at 130 MPH quarter mile and do 3 - 5 runs.
 

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Discussion Starter #6
VENTED OR VANED ROTORS



So what do ventilated rotors accomplish? Well, the concept is that they will help cool the rotors. We discussed earlier that giving up mass for surface area to gain cooling of the rotors should only be done when optimal. Vanes are the optimal method of achieving these goals. The rotors are designed to increase surface area and to flow air in the middle of the rotors. The increased surface area to the air clearly provides for more cooling from the air at the cost of mass. So why does this method work while the others fail? The first reason is that a ventilated design flows a lot of air through a rotor. A ventilated rotor acts as a centrifugal pump sucking air into the rotors. This is why rotors with curved vanes provide better braking.
 

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Okay, so Dogzilla and I were discussing rotors and what not when I posed a question. Where do rotors really come from?
I specifically remember saying the Rotor Stork brought them. :hump:




The above info is enough to drive anyone mad. I say we take a metal bit and a Dremmel, then Cross Drill and Slot them OEM rotors of yours!

I'd still suggest ordering from a reputable source such as StopTech, or Intense Motorsport. Or get a name brand rotor from Ebay or Amazon. Amazon.com actually had sets of gorgeous Brembo rotors online. IMO I'd definitely go with slotted only, and if you plan on doing any high speed track days, I'd also get the rotors with good venting.
 

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You showed a photo of it...but I didn't see any discussion about it.

Coming from a Motorsports background, I can say with certainly that if you are serious about doing any sort of high performance driving....you'd be wise NOT to use Cross Drilled Rotors and to stick with the Slotted. The reason is that the holes that are put in the rotor create what's known as a Stress Riser, which is a concentration of stress caused by the caliper slowing the vehicle. When a Riser occurs, you're more likely to crack the rotor and that's always a bad thing.


Oh...and one other thing to toss out there. StopTech doesn't make their own brake rotors. They have them made by a company called Centric.
 

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neither does Stillen. the rotors they advertise are actually DBA 4000's and 5000's but since they label them as Stillen they charge over $100 more than what DBA (or vendors selling the DBA) do.
 

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I wasn't sure if this was the right place to pose this question, but its a brakes query so I thought its pretty close.

I wanted to know when is a performance brake upgrade advisable for a Z that is purely a street vehicle? The answer would of course be relative to the horsepower output but any information or experience would be great. Over the next year or so I'm going to be modding my Z intensively and one of the first mods on my list are brake upgrades for my car. Looking at 300HP at the wheels minimum, I have got the brembo set up but I'm not sure if that's going to stand up to the spirited driving (lots of braking at high speeds etc).

Thanks in advance.
 

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My $.02 on this one is that brakes and HP aren't necessarily connected. While its certainly nice to upgrade both, having more power won't tax your brakes significantly more. Speeds haven't changed unless you've changed gear ratios. On the streets (where 90% of the Z's on this site spend 95% of their time) you're still speed limit limited. If you're spending time on track, you may hit higher speeds and need better brakes.

I would look into better fluid, pads etc before a bbk. Don't forget, rotors contribute to unsprung weight just like heavy wheels do. I'm not saying you should just be pulling off the track as your brakes go, but you don't need a 16" 19 Pot kit if you're driving on the streets, it'll just slow you down. Heck, a guy on a Lotus forum went with smaller rotors as his were more than he needed, and just hurt him.

~Pat
 

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Time for me to change the rotors. Was searching for EBC rotors and thought I'd mention it here.
 

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QUOTE (SmoothZ @ Feb 27 2010, 09:34 PM) index.php?act=findpost&pid=592598
Time for me to change the rotors. Was searching for EBC rotors and thought I'd mention it here.
i LOVE my powerslot rotors.. but the first 20 miles really sucks.. they warn you about it.. but they don't warn you how bad it's really going to suck lol.. that coating is nasty and you feel like you don't even have brakes
 

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I could do an easy 20 miles around here. Just not too keen on the other drivers that use my roads....lol
 

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The Powerslot Cryo Rotors are great. Like night and day on the track. First time I raced with stock rotors (Hawk Pads) brakes started to fade bad around the 4-5 lap every heat and i'd have to give up a lap to let the brakes cool. Threw the Cryo Rotors on the next year (same track and pads) and I was going at least twice that before it would get just barely mushy.
 

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When you replaced your rotors, did you also flush your brake fluid and put in new fluid? That helps a lot.
 

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neither does Stillen. the rotors they advertise are actually DBA 4000's and 5000's but since they label them as Stillen they charge over $100 more than what DBA (or vendors selling the DBA) do.
I realize this is an old thread, but it came up on a search so other must be able to find it, too!

This is bad information. Stillen was the company that brought DBA into the USA many years ago. The "Pillar Vane" rotors sold are definitely DBA 4000 and 5000 series and are labeled as such. They do not offer the "Street Series", which no one should be interested in anyway. Stillen's pricing is exactly in line with DBA's MSRP and MAP policy guidelines, not the "$100 more" quoted above. They work very closely with DBA to help keep pricing aggressive and fair for a product that is superior to most of the offerings currently on the market.

And, while Stillen does not cast rotors on site (none of the aftermarket manufacturers do, including Centric!), they do have custom tooling made for certain popular and/or function-critical part numbers.

Chris
 

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When you replaced your rotors, did you also flush your brake fluid and put in new fluid? That helps a lot.

Doing this during the week. I got a set of EBC Red's but when I went to install them I saw how bad my rotors looked (OEM, 58K miles). I found OEM rotors for around $80/ea, but for $100/ea I can get a set of StopTech slotted rotors. I think I'm gonna go with the StopTech's.

Has anyone got any experience with StopTech rotors? Good/bad?
 

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StopTech = good. I think a lot of people on a budget are happy with the slotted rotors. I'm going to buy the set over the winter and do a complete brake 'upgrade.'

Got a link for me? Who's the vendor or source? PM if you want.
 
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