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Originally posted by typhoid mary
Here is a quote from another board from the guy who invented these. "My name is Fred Callahan and I am the inventor of the rotors you see posted. The rotors are Intermetallic coated titanium (international patent), and have been in use for over 10 years. Starting from the top, the swept area is actually more than a current Corvette rotor. Coefficient of friction does not depend on surface area, but rather the friction value, multiplied by the force applied (by the caliper pistons to the pad). Surface area has a lot to do with pad wear, or think of a rotor that has a ¼" swept area. It will still stop the car the same amount, but the pads won't last as long. The heat generated is from the material thermal conductivity and mass of the rotor. Nice for show, but useless for the track? Rocky Moran Jr. won the last Formula Atlantic race he ran using four rotors half as thick as these at Laguna Seca. You can either ask him or Price Cobb who owned the car at the time. Review this race and you will see he won by a fairly large margin and was able to easily pull away from the field. In fact, it was so easy that after the race they tore his engine down thinking he was cheating. These rotors have been in many races from SCCA, Late Model Dirt cars, World of Outlaws, many different styles of cars, both ovals and road courses. Brake rotors do not need to store energy, cast iron brake rotors need to be massive because they store energy, and if you cool a cast iron rotor too quickly, it cracks. Ask yourself why would you want a brake rotor to remain hot - wouldn't it make more sense to cool it quickly before applying the brakes again, and inducing more energy? The Specific Heat for titanium is .14 BTU/Lbs/°F, while cast iron is .10 and carbon fiber is .16, so you can see titanium is closer to carbon than it is to iron. If aluminum could withstand the temperature, it would be the best rotor with a .23 specific heat, which is why all of the money was dumped into aluminum metal matrix rotors, but at the end of the day, aluminum is aluminum. The open slot design (US patent pending) performs two functions. First, the slots on the rotor pictured have just about the same surface area as a cast iron rotor, and surface area is the important factor for cooling, which is why heat sinks are usually aluminum, and have a lot of machined surfaces and protrusions, to increase the surface area to allow for radiant cooling. Secondly, the angle of the slots are important for initial bite. Depending on the situation, you may want a higher or lower initial bite, most street cars would require less. The most important factor I haven't seen mentioned yet (probably because it is a pro and not a con) is the lower inertia these rotors offer over cast iron. It may be only 50 lbs. static weight, but this translates to hundreds of pounds rotating weight - which allows the car to accelerate quicker (not having to spin up the heavy cast iron rotors), decelerate quicker (not having to stop spinning the heavy cast iron rotors), quicker response time for the suspension (less weight means the spring isn't compressed as far over a bump and keeps the wheel planted to the road), and less spring rate required, for the same reason, allowing greater flexibility in vehicle set-up. An example of inertia, two kegs of beer are rolling down a hill at you, one is empty and the other is full, which one do you want to get in front of? Now, LG is mad at me because of a comment I made to him at the SEMA show, and Lou, if you want to go over that in public forum, I'd be happy to accomodate you. Andy was given a free set for his car to try. I have e-mails stating the first few tracks went fine, but eventually, 35-40 minutes into a race, the pads would get too hot and begin to fade - I also have the e-mail where the rear blades were continued to being used, and the cast iron vented rotors were back on the front only. I offered a set of vented titanium rotors, but not for free this time, and received no response. The blade rotors are certainly not for every application, which is why we offer vented rotors to some, and blades to others. The Mosler car was interested in competing in performance, with acceleration/deceleration as a primary goal, not running the 24 hours of LeMans - if that was the case, we would have put vented rotors all the way around. If you think the rotors are too expensive, find me an inexpensive source for titanium. Nobody is getting rich off of these things, I still have a day job, this isn't what I do for a living. I hope I've answered some of your questions." I guess only time will tell if these things are worth the money.
if htis person thinks that specific heat is a major part of braking performance, then why not use copper? its specific heat is like 2x that of aluminum? probably cuz specific heat isnt as important as he thinks...2005 Legacy GT Ltd, Garnet Red Pearl
speak softly and spool a big turbo
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