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Discussion Starter · #1 ·
Are aftermarket rotors going to weigh less than stock? Is it substantial if they do? What manufacturer would you guys recommend for rotors (weight and braking capabilities for the street)
 

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please post in the correct forum..

No aftermarket rotors are not lighter than stock. They are about the same.

I went with Stoptech slotted rotors. They are great!
 

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Typically, going bigger means more weight. If you go bigger and lose weight, you're lookin at very high prices (ceramic, CF brake rotors, etc.)
 

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I don't know of a company that makes lightweight rotors either. I've heard good things about the StopTech slotted rotors in terms of braking, but I've never read anything about lighter rotors.
 

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im sure you could find some type of carbon rotors that weight nothing, but you will pay like 10k for them.. I saw some full carbon fiber wheels once. weight was only 2 lbs
 

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If you can find a two piece rotor, the center section is usually made of aluminun so the overall weight if the rotor will be less. If you have the Brembos, I believe that Stoptech makes 2-piece replacements for them. I don't think that I have ever seen 2-piece non-brembo replacements.
 

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the weight would be negligible. Also since it is very close to the axle the moment of inertia difference would be near zero between light rotors and heavy rotors.
 

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So then heavier rotors wouldn"t affect rotational mass?
they will not affect rotatation inertia. Without going into a physics lesson:

Mass affects acceleration in a line

Inertia affects rotational acceleration (i.e. wheels, flywheels, axles, etc...)

You will never see a difference in your car's speed or acceleration by going to heavier rotors.
 

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Isn't mass related to inertia? The larger the mass the more inertia. Acceleration is a change in speed or direction. It is easier to accelerate a smaller mass than a larger mass. I can be easily corrected, but according to Newton's second law of motion doesn't
acceration = force/mass? Acceleration and mass have an indirect relationship in that the
smaller the mass (inertia) the larger the acceration with the same force (force = m x a),
likewise, the larger the mass the slower the acceleration. If you have a car with 300 hp and 300 torque, the car with less mass will accelerate at faster rate.

With all that technical talk, I would put my money on the lighter car/with lighter brakes
accelerating at a faster rate. Let me know what you think?
 

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Isn't mass related to inertia? The larger the mass the more inertia. Acceleration is a change in speed or direction. It is easier to accelerate a smaller mass than a larger mass. I can be easily corrected, but according to Newton's second law of motion doesn't
acceration = force/mass? Acceleration and mass have an indirect relationship in that the
smaller the mass (inertia) the larger the acceration with the same force (force = m x a),
likewise, the larger the mass the slower the acceleration. If you have a car with 300 hp and 300 torque, the car with less mass will accelerate at faster rate.

With all that technical talk, I would put my money on the lighter car/with lighter brakes
accelerating at a faster rate. Let me know what you think?
I disagree and this and here is why. Inertia is related to Mass but is more dependant on WHERE the mass is located. Why do you think ice skaters have to tuck in their arms and legs to spin so fast? The further away mass is from the axis of rotation (i.e. axle) the more impact it will have to the inertia. Rotors are right on the axle. Compared to the wheels and tires which spread further away from the axle and collectively weigh in around 50lbs each, the rotor has minimal impact on the Inertia.
 

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You got street cred. Thanks for the lesson! :yourock:
 

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We actually did some calculations on wheel/tire get the overall impacts to weight, inertia, and car acceleration. I dont think i have the numbers anymore, but if i had to i could produce them.
 

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I dont know the physics of it but I'm petty sure that the reduction of unsprung weight has a great affect on vehicle performance. I'll do some digging to see if I can come upwith more info.
 

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A 2 piece rotor will weigh less than a one piece - so, for marketing purposes, yes there are lightweight rotors.

However, the most important aspect is having a rotor that interacts well with your intended pad. Unsprung weight aside, you'll have a FAR more capable car selecting a proper set of rotors that suit your needs than automatically choosing the lightest rotor on the block.
 

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While I think weight is always a consideration when talking automotive performance, in the case of brakes, it should definatley NOT be your biggest priority. Heat dissipation and material quality should be your number one focus when purchasing rotors.
 

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Discussion Starter · #18 ·
So what rotors would you guys reccomend for a nonbrembo setup? I'm going to use Hawk pads and it's definitely time for new rotors.
 
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