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Thread: notch stresses on the frame

  1. #31
    Registered User wagonmaster's Avatar
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    Can't see how frame flex is ever good. You would be popping out windows, doors wouldn't open, body panels won't line up, etc. You want a frame to be as strong as possible for the suspension to work as best as possible. Naturally you can't make a frame that doesn't flex, but I would think you would want to minimize any flex.

    As for the c-notch thing, if the frame is the only variable, then yes, removing half the frame height will certainly weaken it. The plate helps to overcome that. But it isn't just the frame, the body is part of vehicle strength too. I would be interested to see data with a body attached.


    Quote Originally Posted by phatfarmer2 View Post
    i think a key thing to also think of is a fully boxed frame, as well as over reinforced frame is not good as well... a car or trucks chassis is to flex some, this flex asorbes stress which prevents cracking... with out a frame or uni body flexing, stress cracks are more prone. food for thought as well.

    you want the chassis to be strong but not overly strong

  2. #32
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    Quote Originally Posted by supernova View Post
    how are first gen pickups and blazer frame different. They are pretty fucking similar, besides general shape of the rails firewall back.
    the back is half is different on all 3 s10/s15 truck, four door and two door blazers/jimmys
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  3. #33
    Doesnt look like this supernova's Avatar
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    im aware of that, but what does the shape of the rails have to do with strength, which is the point you seem to be making. Both of them are c channel, and the same thickness material. Again how are they "completely different"

  4. #34
    I'm BATMAN! Harley's Avatar
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    Quote Originally Posted by BigP View Post
    And I think your trying to say surface area not taller.
    I mean exactly what I said. When calculating bending stresses and most any stress with beams the moment of inertia is required. The formula for that on a square section is I = b * h ^ 3 / 12 where b is the width and h is the height of that section. Notice how h is to the third power. That means that as h changes the moment of inertia changes drastically. None of the other variables in the stress equation have an exponent meaning that h is the single most significant variable.

    Quote Originally Posted by wagonmaster View Post
    As for the c-notch thing, if the frame is the only variable, then yes, removing half the frame height will certainly weaken it. The plate helps to overcome that. But it isn't just the frame, the body is part of vehicle strength too. I would be interested to see data with a body attached.
    This is the exact thing I'm cautioning against. Again there is no replacement for the frame height. While plating does add reinforcement it cannot return the full strength of the original frame alone without out adding an extremely thick plate and even then...

    Yes the body is part of the strength too, but it hasn't changed, so the whole assembly is still weaker than when you started. Besides the body strength doesn't apply to a pickup. The bed pretty much just goes where the frame does.


    If this still isn't sinking in for anyone try a simple experiement. Grab a ruler, try bending it with the numbers facing up. Should bend really easy. Rotate it 90 degrees with the numbers facing toward you. Try bending it again and it will not be so easy. No matter how wide you make the ruler it will not gain much strength with the numbers up, but will only get significantly stronger when the numbers are facing you.

    Or watch this video. Not the same situation, but a similar concept that relies on the same variables. 0:40 to 2:20 shows how the difference in height affects bending.
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  5. #35
    will work for food! phatfarmer2's Avatar
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    1st gen and second gens are the same frame of like kind. as well as blazer to pickup are pretty damn well near the same! as far a piss poor, it was used from 82-04 guess the frame is junk. lol i wouldn't hesitate to swap a s10 or blazer frame under any vehicle.
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  6. #36
    will work for food! phatfarmer2's Avatar
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    Quote Originally Posted by wagonmaster View Post
    Can't see how frame flex is ever good. You would be popping out windows, doors wouldn't open, body panels won't line up, etc. You want a frame to be as strong as possible for the suspension to work as best as possible. Naturally you can't make a frame that doesn't flex, but I would think you would want to minimize any flex.

    As for the c-notch thing, if the frame is the only variable, then yes, removing half the frame height will certainly weaken it. The plate helps to overcome that. But it isn't just the frame, the body is part of vehicle strength too. I would be interested to see data with a body attached.

    like i said you want a frame to be strong, but not too strong.. a good example is most crossmemebers are riveted in (some not all) this account for the frame to flex some. Also for collision purposes
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  7. #37
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    of like kind they are pretty close. I believe the frame rails are the same but there's small things like gas tank cross members and carrier bearing cross members which make a difference. They changed there steel mixture in later 1st gens to because of rust.

    I should have said the first gen channeled 4 door frame is piss pore. That extra 7 inchs really adds a lot tords frame flex. I can hear stuff flexing when turning in to steep drive ways. It drives me nuts.
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