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Old 11-24-2014, 09:00 PM   #1
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Default 11.75" Directional rotors @ SuperMiata

We now offer affordable Directional Vane 11.75 rotors for our 11.75 BBK at $89 each. Made for SuperMiata in the USA from high quality material. Our directional is about 1lb heavier than the $36 Wilwood 160-0471 straight vane "econo" rotor that is cast in Mexico out of a lower quality iron. Wilwood cast their premium rotors here in the US also.

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Old 11-25-2014, 02:38 AM   #2
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Outstanding! I assume this rotor is the same high quality material as SM 11" directional rotors. If so this is sure to be a hit. Once I burn through my spares I'll torder a set.
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Old 11-25-2014, 01:05 PM   #3
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Originally Posted by k24madness View Post
Outstanding! I assume this rotor is the same high quality material as SM 11" directional rotors. If so this is sure to be a hit. Once I burn through my spares I'll torder a set.
Yup. Same material, foundry, machinist and basic design.
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Old 11-25-2014, 05:23 PM   #4
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Damn, I already have a spare set of the non directional sitting here!

Are the differences between directional and non directional noticeable/significant?

I was going to say i have no heat problems since upgrading to the 11.75 set (which was an amazing improvement from the 11") BUT for a few race meetings I ran a cooler duct to one side and not the other (forgot to put it back on when it fell off) and noticed a significant difference in brake pad wear on the non ducted side....
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Old 11-25-2014, 06:21 PM   #5
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Damn, I already have a spare set of the non directional sitting here!

Are the differences between directional and non directional noticeable/significant?
Huge difference in stability of the rotor at temp. It helps prevent coning and drag. also more thermally stable at higher temps. How much more stable it is all depends on the engineering behind the veins shape, and size.

Link to my basic Mind puke of brake info
https://www.miataturbo.net/general-m...estions-81577/


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there are allot of different aspects when it comes to a rotor.
What is it made from (Iron, Steel, Aluminum, Carbon ceramic, Carbon Carbon)
Where is it made
Is it 2 piece (hat made from aluminum, Rotor ring made from iron)
if it is 2 piece does it float?

Not wanting to spend all day i'll try to keep the answer short. and focus on the standard parts store rotor.
Standard rotors that you find on Rockauto, Autozone, and so on come from china. They are covered and machined with oil, the material to make them is not as pure as it should be, and are never made engineered for racing. allow me to explain.

The machining process for Chinese rotors involves blasting the machining surface and tools with a oil to keep them cool, this lowers maintenance costs on machines. Then factory workers will warp the rotors with an oil impregnated paper. This oil is in an attempt to prevent rust, at that it works well. The problem with using so much oil is that, it will impregnate itself into the iron. once that iron is impregnated the oils will come out under extreme braking. Most of the time when you see issues creating and keeping a transfer layer, the oil inside the iron is causing that issue. It impurities in the rotor are kicking the transfer layer off. Racing companies like PFC, Brembo, AP, will cut the rotors "dry". Dry means to machine the parts without any oil. it is more expensive to do this but will increase the rotors ability to obtain and keep a transfer layer.

Next is what it's made from. Iron is easily one of the best materials used for rotors. Size for size an iron rotor will outperform a carbon ceramic rotor. if you have 14" rotors one in carbon ceramic and one in iron, the iron one will generate a more consistent and higher TQ output. Not to go too off track but that is why you see 15-16" carbon ceramic rotors on oem vehicles. The oem manufacturers need the increased size to get the performance. but Carbon ceramics will outlast a iron rotor. ...sorry back on topic, right iron.. Iron is one of the densest materials in the universe. also how pure it is in the casting for a rotor makes a considerable margin in braking performance. rotors that are casted in china are known to have quite a few impurities, and are labeled incorrectly. anyone that has dealt with 304 *chinese* stainless will know what i'm talking about. these impurities will have a decreased effect on braking performance. I like to find Rotors manufactured and casted in the usa. the us has a higher standard of casting. again PFC, AP, and brembo all are manufactured in the USA, GB, or Italy.

finally the engineering in the rotors could take year to explain, so i'll focus on balancing only. when a rotor gets hot it cones, it beds, and it looks like a wave. it's never still. The material is constantly flexing. think about a top fuel dragster tire in slow motion.. it's not 100% the same but it is close. that rotor is constantly trying to keep itself together and not explode. in order to stop a rotor from shaking the wheel all manufacturers will balance them. Top Motorsports brake manufacturers will balance the rotor by cutting the entire outer perimeter of the rotor on a lathe. this ensures that when a rotor is at thermal capacity, there will be no places of excess or minimal material. it makes the rotor stronger, and more resistant to cracking. part store rotors balance the rotors by finding the heavy spot on the rotor and cutting that off.

what not to do.


In Motorsports this is a huge no-no. the hard edges give a place for cracks to start, the material has a thin spot on the rotor, and it means that the material that is spinning is not balanced through the assembly. it can lead to a cracked rotor and can lead to problems with a long pedal.

In conclusion, :P. is high quality rotors a waist? Like tools good quality parts are never a waste. On average a motorsports rotor will outlast a parts store rotor long enough to justify the price. Parts store rotors can work, they also let allot of people down. If it was my money, paying for my track day, i'm putting the parts on my car that will insure that i have a fun weekend. i'm not looking not fight the $30 rotor that costed me $800 of track time. Allot of people might say "they worked fine for me". Truth of the matter is 80% of the motorsports population knows how to build a motor, 10% know how to build a braking system. when the brakes that they said "worked fine" didn't work "fine", and that person has no idea what the problem actually is.
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Old 11-28-2014, 09:08 PM   #6
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Damn, I already have a spare set of the non directional sitting here!

Are the differences between directional and non directional noticeable/significant?
I think the quality of the material will make the biggest difference.
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Old 11-28-2014, 11:09 PM   #7
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The iron composition can make a large enough difference in rotor life as well that it becomes cheaper to run the USA-made rotors in many cases.

-Ryan
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Old 11-28-2014, 11:49 PM   #8
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Originally Posted by mx5-kiwi View Post
Damn, I already have a spare set of the non directional sitting here!

Are the differences between directional and non directional noticeable/significant.
yes, that is why we went to the trouble of making them. Comparing a lower quality iron straight vain to a high quality iron directional vane there will be a big difference. On a car that really isn't pushing it brakes that hard, you might not notice much difference. But on a car that's really killing its rotors in a weekend or two you might expect two or three times the life out of the higher quality rotor.

The 11 inch version of the economy 11.75 Wilwood is pretty bare bones. My experience with those was that on a fast car you can crack them in a day. The Wilwood HD 36 are really nice rotors but they're like $140 each.
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Old 11-29-2014, 10:43 PM   #9
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Originally Posted by emilio700 View Post
yes, that is why we went to the trouble of making them. Comparing a lower quality iron straight vain to a high quality iron directional vane there will be a big difference. On a car that really isn't pushing it brakes that hard, you might not notice much difference. But on a car that's really killing its rotors in a weekend or two you might expect two or three times the life out of the higher quality rotor.

The 11 inch version of the economy 11.75 Wilwood is pretty bare bones. My experience with those was that on a fast car you can crack them in a day. The Wilwood HD 36 are really nice rotors but they're like $140 each.
Dont use a cracked rotor as "time to change the rotor" marker. If your rotors are cracking you have a serious issue and it needs to be addressed.

A rotor sould be replaced after they are 1.5mm thinner than the original thickness.
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Old 11-29-2014, 10:59 PM   #10
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Dont use a cracked rotor as "time to change the rotor" marker. If your rotors are cracking you have a serious issue and it needs to be addressed.

A rotor sould be replaced after they are 1.5mm thinner than the original thickness.
Thanks for the tip. .060 is somewhat arbitrary though. Some rotors are done at .040 some can go past .080

Heat checking happens on rotors and that's not going to change no matter how bitchin your brakes are. Most of the cars in our shop run carbotech so we get pretty good rotor life. Typically 2-4 sets of race pads before the rotors are either too severely heat checked or starting to warp. I can't remember the last time I actually put a micrometer on a rotor.

The rule of thumb that we use and what I tell my customers (not a subject of debate for this thread) is replacing the rotors when any single heat checking crack is more than 30% of the swept width of the rotor or it reaches the outer perimeter.

I agree though, the cooler they run the less heat checking they will have when they are simply too thin and begin to warp.
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