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Projects Drive Train Alignment

Discussion in 'Traditional Hot Rods' started by 66vwghia, Aug 19, 2019.

  1. 66vwghia
    Joined: Jul 24, 2010
    Posts: 62

    66vwghia
    Member
    from Tennessee

    Planning to build a hotrod frame, Ford rear axle has a 2" offset pinion. Does the motor/trans need to be offset 2" to match or can the drive shaft u joints manage this little difference?
     
  2. pitman
    Joined: May 14, 2006
    Posts: 5,148

    pitman

    Driveshaft length matters, as to your ?
    Offset if: you have steering box needing room in left front region.
    See recent thread on driveshaft-u-joint angles.
     
  3. 66vwghia
    Joined: Jul 24, 2010
    Posts: 62

    66vwghia
    Member
    from Tennessee

    Great point, longer drive shaft means greater angle change. Thank you.
     
  4. Turn it on it’s side and look at it

    Same same
     
    mgtstumpy and X-cpe like this.

  5. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,958

    X-cpe

    Can you explain? My thinking would result in the opposite. Draw 2 parallel lines on a piece of paper about an inch apart. Put an X on the left hand line close to the top. Start at the bottom of the right line and place a series of X's a couple of inches apart going up the line. Now, using the left X as a pivot point run your ruler across each of the right hand X's and observe the resulting angles.
     
    scrap metal 48 and Hnstray like this.
  6. BJR
    Joined: Mar 11, 2005
    Posts: 9,814

    BJR
    Member

    No it doesn't!
     
    Hnstray likes this.
  7. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,214

    mgtstumpy
    Member

    Irrelevant, provided pinion centreline is parallel to engine / transmission centreline, provided that engine / transmission centreline is parallel to centreline of frame. Many manufacturers have off set pinions and not every car / light truck has a centred pinion. Your rear axle needs to be square in frame, measure with a trammel bar if unsure and frame is square, check diagonals.
    Also ensure pinion angle is correct and corresponds with engine / trans angle. I won't go into detail as it's been flogged to death like a dead horse here on the forum.
    The longer the driveshaft, the shallower the arc.
    https://www.dragzine.com/tech-stories/pinion-offset-guide-and-how-to-with-chassis-engineering/
    upload_2019-8-20_11-38-16.png
    upload_2019-8-20_11-37-12.png
    Arc.jpg
     
    Last edited: Aug 19, 2019
    pitman and Hnstray like this.
  8. lostone
    Joined: Oct 13, 2013
    Posts: 2,820

    lostone
    Member
    from kansas

    Simply put it's not a problem, ford has been using a 9" how many years ? AND they've been using them with that same offset since day one.

    Ford doesn't offset the motor either, the drive shaft offsets to the side in any ford with a 9" so that means you can do the same thing ford has been doing too, center the motor in the frame, center the rear end in the frame and enjoy.
     
    lurker mick and Bandit Billy like this.
  9. 66vwghia
    Joined: Jul 24, 2010
    Posts: 62

    66vwghia
    Member
    from Tennessee

    Thanks to all that provided insight, I appreciate your shared knowledge and experience.
     

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