Driveshaft angles, demonstration

Discussion in 'SRT Hellcat General Discussions' started by Slowhand, Mar 3, 2015.

  1. Slowhand

    Slowhand Gold Member

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  2. magnummrk

    magnummrk SRT Hellcat Supporter Gold Supporting Member

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  3. Blackdevil77

    Blackdevil77 Silver Member

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    Interesting, thanks for posting. Is this why the Hellcats use a 2 piece drive shaft? There isn't a straight shot to the diff from the transmission and they need to angle it?
     
  4. Slowhand

    Slowhand Gold Member

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    Based on this and some other info I get the idea it is because the 2-piece units have different harmonics/resonant frequencies per piece and 1 may dampen the other. But that may be unadulerated BS also. I am not a mechanical engineer. But at 200mph, the driveshaft is spinning much faster than most. To make it stronger, easiest to make it larger diameter. But that creates more angular momentum to overcome. Tradeoffs everywhere.
     
    Last edited: Mar 4, 2015
  5. B5 Blue

    B5 Blue Platinum Member

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    Last edited: Mar 3, 2015
  6. CasualObserver

    CasualObserver Senior Hellcat Member

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    Typically a 2 piece driveshaft is made to prevent whip and hitting a "critical speed". When a driveshaft hits a critical speed it can begin to violently whip and come apart. Splitting the shaft into multiple shorter sections typically raises the critical speed. Think a long vs short guitar string, the longer string will have a lower resonant frequency than a short string all else being equal. Also, typically a shorter driveshaft section will have a much lower whip amplitude at its resonant frequency. The amplitude would be how much the shaft deflects when at a resonant frequency. The goal is to tune the length of the shaft so a critical speed is never hit during operation.
     
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  7. RadCat

    RadCat Left Shark

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    And this is why I mentioned that there may be angles that we don't know about, or other issues for the reason that Dodge installed a 2pc driveshaft from the factory. But it is hard for me to believe that is the reason considering the bottom of these cars are pretty flat, not like a 15ft tall 4x4 diesel with military axles and a drop from the rear of the transfer case output shaft, 3 feet down to the rear axle.

    Until I can lay under one myself, with an inclinometer and take some measurements, I'm just daydreaming...and have no idea.

    But it looks like to me, since there are no obvious steep angles, that a single piece, quality made, well balanced driveshaft should be fine.
     

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