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Thread: Brake rotor material?

  1. #21
    Senior Member
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    You sure Pat? 1018 steel rotors?
    Any views or opinions expressed by me may in no way reflect those of Stewart-Haas Racing, Kettering University, or their employees, students, administrators or sponsors.

  2. #22
    Originally posted by AxelRipper:
    You sure Pat? 1018 steel rotors?
    Better than the Ti rotors our solar car team used a few years ago...
    Dr. Adam Witthauer
    Iowa State University 2002-2013 alum

    Mad Scientist, Gonzo Racewerks Unincorporated, Intl.

  3. #23
    Originally posted by Adambomb:
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AxelRipper:
    You sure Pat? 1018 steel rotors?
    Better than the Ti rotors our solar car team used a few years ago... </div></BLOCKQUOTE>

    And still not nearly as good as iron (the material).

  4. #24
    As a completely serious question:

    Ignoring that aluminum is lower strength and loses strength more quickly as it heats up, I was under the impression that the thing that is fixed in a brake rotor is total heat capacity, not strength or weight. That is, an aluminum rotor should need to weigh as much or more than a steel or cast iron one for the same application.

    Am I missing something obvious here? I guess maybe in practice for fsae cars an iron rotor that is actually at the limit heat capacity wise would need to be too small to actually work ?
    GTMS 2007-2011
    CVD Equipment Corporation 2011-present

  5. #25
    Some years back - it is unclear how many - someone made an alloy of aluminum that they called "Aluminum Metal Matrix." And made brake rotors from it. It was wildly successful, had a brilliant reputation, and professional race teams quickly bought all that had been produced. This experiment was not repeated. A few years back another someone created another alloy, calling it the same thing, and made (is making?) brake rotors from it. I have heard nothing of the success.

    My perspective is that the brake pad material is the real problem with such a solution. With steel or iron rotors you have a large number of brake pads that you can use, each with different properties. For example, to get proper balance with my brake system I use a different compound front and rear (and yes, I have also modified my calipers and master cylinders). With aluminum, or AMM, or titanium, you are very much more limited.

  6. #26
    someone made an alloy of aluminum that they called "Aluminum Metal Matrix." And made brake rotors from it.
    Metal Matrix Composite (or MMC) rotors were and are still around in the automotive industry, and yes, there have been aluminum based MMC's used for brake rotors. You can find more information about them on the googles.

    In MMC brake rotors when aluminum is used (as far as I know) they often solve the issue of pad material by bonding a ceramic to the effective braking surface. I don't see any reason why it wouldn't also be possible to braze something like cast iron onto the surface either, but I'm not really certain of that. Since MMC's can be manufactured in intricate shapes like say, a honeycomb core rotor, the strength can be extremely high while allowing the bulk of the rotor to remain thin enough to bond a material with suitable braking qualities.
    Owen Thomas
    University of Calgary FSAE, Schulich Racing

  7. #27
    Originally posted by Ben Coburn:
    Ignoring that aluminum is lower strength and loses strength more quickly as it heats up, I was under the impression that the thing that is fixed in a brake rotor is total heat capacity, not strength or weight. That is, an aluminum rotor should need to weigh as much or more than a steel or cast iron one for the same application.

    Am I missing something obvious here? I guess maybe in practice for fsae cars an iron rotor that is actually at the limit heat capacity wise would need to be too small to actually work ?
    You have missed something obvious - the specific heat of the material. The specific heat of aluminium is double that of iron. So an aluminium rotor will absorb twice as much heat as an iron rotor of the same mass for the same temperature increase. That is good.

    On the other hand high thermal conductivity is good and bad. The bad is that plain (not ventilated) rotors are cooled from the same surface as the heat is applied (the friction surface). During heavy braking, an iron rotor is much hotter on the surface than internally. This improves heat transfer from the rotor.

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