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Thread: studs vs bolts , blah blah

  1. #26
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    can I say u r overthinking this?

  2. #27
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    I don't over think when I buy them myself. I was just trying to provide info.

    Buy studs, ask about installation. Install. Drink beer.

    Sent from my SM-T713 using Tapatalk

  3. #28
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    Quote Originally Posted by lelandr View Post
    Sorry I wasn't clear, and I hijacked a little to cover all fasteners.

    You don't want to yield the bolt, but you do want strain (deform) in the elastic region. The reason for the higher torque spec on harder fasteners of a given dimension (M12 10.9 or 12.9, for instance) is due to the stretch that you want in the bolt. Clamping force between the parts is one aspect, but the orthogonal force between the threads, which is what keeps the bolt from backing out, is equally important.

    Again, I'm not saying that it won't work. I just wanted to point out that:
    1 Higher strength is not always better for a given application
    2 Contact the seller and make sure that you understand if there are changes into the torque spec.

    Sent from my SM-T713 using Tapatalk
    I really feel like I should bow out of this since I'm out of my element so take it for the uneducated nothing that this is worth but based on what I know, all steels stretch and deform pretty much the same up to a very high point (around 60k PSI I think), it's only once you get close to yield that the harder stuff starts to deform less (esp when the others break obviously lol). So I really don't think at this torque level for an M12 fastener, 10.9 vs 12.9 will make any difference in terms of elastic deformation for backing out. But that's just my opinion and no one should listen to me.

  4. #29
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    As an aside, I installed the 82mm and with spacers (5mm front and 10mm spacer rear) they work fine, but lug nut install would be easier with the 92mm from B-World. The shorter 82mm are however more aerodynamic and lighter.

    Feff

  5. #30
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    Quote Originally Posted by TheJuggernaut View Post
    I really feel like I should bow out of this since I'm out of my element so take it for the uneducated nothing that this is worth but based on what I know, all steels stretch and deform pretty much the same up to a very high point (around 60k PSI I think), it's only once you get close to yield that the harder stuff starts to deform less (esp when the others break obviously lol). So I really don't think at this torque level for an M12 fastener, 10.9 vs 12.9 will make any difference in terms of elastic deformation for backing out. But that's just my opinion and no one should listen to me.
    My 5 minutes of googling fasterners seems to agree.
    FYI...

    A dry 10.9 or 12.9 nut/bolt torqued to 100Nm provides about 9,400 lbs of clamping force.
    At 100Nm torque (dry), a 10.9 bolt is at 60% of proof load, and a 12.9 bolt is at 52% proof load.

    Fun stuff.

  6. #31
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    Quote Originally Posted by TheJuggernaut View Post
    I really feel like I should bow out of this since I'm out of my element so take it for the uneducated nothing that this is worth but based on what I know, all steels stretch and deform pretty much the same up to a very high point (around 60k PSI I think), it's only once you get close to yield that the harder stuff starts to deform less (esp when the others break obviously lol). So I really don't think at this torque level for an M12 fastener, 10.9 vs 12.9 will make any difference in terms of elastic deformation for backing out. But that's just my opinion and no one should listen to me.
    You're mostly right. The elastic modulus (Young's modulus) has much less variability in steels than the yield and tensile strengths. Even metallurgists will tell you that's a hard number to nail down.

    A steel with a higher yield strength will enter plastic deformation at a higher stress than a one with a lower number (this plastic deformation will come with a hardening). A 12.9 will require 20% more stress (F/A) to break than a 10.9. FWIW, 12.9 means that the ultimate tensile strength (breaking point) is at least 1200MPa. Generally speaking, yield strengths are related to tensile proportionally.

    Again, please note that I'm NOT saying that you would necessarily have a different spec, but due to alloys or microstructure required for the hardened fasteners that you MIGHT have a different spec, and should ask rather than assume.

    I feel that I have a very strong metallurgical and mechanical background, but a 5 minute phone call on a new set of studs isn't much of an imposition.

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