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330 GTC brake disc thickness

Discussion in 'Vintage (thru 365 GTC4)' started by fasthound, Feb 18, 2025.

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  1. fasthound

    fasthound Formula Junior
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    #1 fasthound, Feb 18, 2025
    Trying to determine the correct rear disc thickness. Here are two different sources saying two different thicknesses. Roush and Apen say 12mm for rears on a 330 GTC with Girling brakes, and 9.5mm for the 365 GTC with ATE brakes. GT Car Parts quotes the thinner disc for the 330 GTC. Two different specs are shown below. Which is correct??

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  2. fasthound

    fasthound Formula Junior
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    #2 fasthound, Feb 19, 2025
    Well, I think I have my answer (via GT Car Parts…thank you!)

    Apparently the Roush/Apen book data refers to a Ferrari technical bulletin 110/3 dated 1/22/73. Specs showing the thinner thickness are from Ferrari technical bulletin 280/2 dated 1/9/77.

    And now you know. Luckily, that means my rear discs are fine at 9.3mm! So that’s one less expense this winter :)
     
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  3. TTR

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    #3 TTR, Feb 19, 2025
    Glad you figured this out, but what does that “as built” 330 GTC book says about this ?
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #4 Rifledriver, Feb 19, 2025
    I doubt it says anything. The guy who wrote it is a friend and it is not meant to be a shop manual.
     
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  5. fasthound

    fasthound Formula Junior
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    #5 fasthound, Feb 19, 2025
    It doesn’t give specifications. It’s a judging guide and documents the cars to the extent that show judges would be interested. Don’t get me wrong…it’s an invaluable aid, but it is not a technical manual.
     
  6. TTR

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    #6 TTR, Feb 19, 2025
    No problem and thanks for the clarification.
    I believe I have copy somewhere, but haven’t had a need or time to read it yet and was just wondering.
     
  7. TTR

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    #7 TTR, Feb 19, 2025
    Not to diminish authors efforts, but I was just thinking if it's intended as a judging guide, wouldn't it be fair to expect it distinguishing what type of brake system & relative components, perhaps even including any potential changes/supersessions/upgrades that were implemented throughout the production timeline so that a judge inspecting the chassis & undercarriage could and should be able to determine the subject having authentic/correct items present, just like exhaust, shocks/springs, steering, tires, wheels, etc ?
    Or perhaps it does (as I mentioned, I haven't read it yet) ?
     
  8. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #8 Rifledriver, Feb 19, 2025
    Or perhaps we can stick to the topic of brake rotor thickness.
     
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  9. SCantera

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    #9 SCantera, Feb 20, 2025
    I met with Clete at the Festival of Speed here in St Petersburg. He lives not far away in a nice 'burb in the area.
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  10. SCantera

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    #10 SCantera, Feb 20, 2025
    Sorry….couldn’t help it. What were we talking about?
     
  11. TTR

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    #11 TTR, Feb 20, 2025
    Last edited: Feb 20, 2025
    I agree and thought I was. :confused:

    OTOH, staying straight & narrow on any topic would be quite unusual in this forum, don’t you think ?
    Most contributors, including me & you, don’t seem to possess that ability.
     
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