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How much slip does the stock front driveshaft have?

Discussion in 'Differential & Driveline' started by Pender1, Apr 24, 2019.

  1. Pender1

    Pender1 Full Access Member

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    Truck Year:
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    Truck Model:
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    Engine Size:
    305|5.3L
    I moved the axle in my Blazer forward an inch and have just now gotten around to regearing it after my 14 bolt swap. The problem is my slip in the driveshaft seems to stop right about the time it gets to the yoke at ride height. Looking at the witness marks, it looks like it only goes about 2" from full compression before it stops (on what, I'm not sure). Does that sound right or is there something funky going on?
     
  2. SquareRoot

    SquareRoot Full Access Member

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    Engine Size:
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    I went thru this recently and conducted some in depth testing to confirm my front shaft movement. I was concerned about the shaft bottoming out after swapping in a D60.
    The bottom line is it doesn't move as far as you would think. I unbolted the spring hangers (truck on jackstands) and let the front axle hang (full droop) and marked the shaft. Then I jacked up the axle against the bumpstops (full compression) and marked it again. Result:
    From ride height the shaft only compresses 1/2 inch. On extension, it moves about 5/8th inch.
    Conclusion, At ride height, unbolt the flange or u-bolts, slide the shaft forward and if you have at least 5/8" travel, call it good.

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  3. Pender1

    Pender1 Full Access Member

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    Engine Size:
    305|5.3L
    At ride height I seem to be at or slightly past full extension.
     
  4. SquareRoot

    SquareRoot Full Access Member

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    Engine Size:
    350
    I would do what I did just for piece of mind. You don't want the shaft coming out unexpectedly. Note that the shaft only moves one direction until the springs reach thier Apex (flat) then the direction reverses. That's why several inches of vertical movement only results in slight horizontal movement. It took me going thru the exercise to understand that.
     

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