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Hot Rods Front end setup

Discussion in 'The Hokey Ass Message Board' started by Lizzie deville, Jun 21, 2021.

  1. Lizzie deville
    Joined: Jun 21, 2021
    Posts: 3

    Lizzie deville

    Do you measure the 7° lay back the batwing or on the kingpin. I did 7° on the batwing for my straight axle and that puts the kingpin at roughly 15°. Want to make sure this is right before I do my final welds. Running a spring behind setup. TIA!!
     
  2. FrozenMerc
    Joined: Sep 4, 2009
    Posts: 3,093

    FrozenMerc
    Member

    I assume you are referring to setting caster angle when you say layback angle. In that case, you need to measure on a surface that is parallel to the kingpin axis.

    [​IMG]
     
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  3. hemihotrod66
    Joined: May 5, 2019
    Posts: 968

    hemihotrod66
    Member

    Measure all your alignment numbers off of the kingpin....
     
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  4. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 2,269

    woodiewagon46
    Member
    from New York

    The kingpin boss is the true place to get the measurement, the batwings can be welded on at any unknown angle.
     
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  5. Lizzie deville
    Joined: Jun 21, 2021
    Posts: 3

    Lizzie deville

    Caster angle is what I'm trying to set. Is 7° the correct amount of caster angle?
     
  6. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,535

    Doublepumper
    Member
    from WA-OR, USA

    Seven degrees will most likely work OK. P & J recommends five degrees.
     
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  7. wheeltramp brian
    Joined: Jun 11, 2010
    Posts: 2,556

    wheeltramp brian
    Member

    I put up to 10 degrees in my cars. As it makes it a little harder to steer in a parking lot it goes straight as an arrow down the highway
     
    Lizzie deville and '40 Coupe Fan like this.
  8. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,672

    Jmountainjr
    ALLIANCE MEMBER

    Do you have the car mocked up enough to account for tire rake? That should be done first due to increasing rake reduces caster. If not at least set the frame up with 2 or 3 degrees of rake then measure your caster. And if you are following the math you can see with an aftermarket front crossmember that has 10 degrees of built in caster gets installed with the frame flat in a jig, you give up 2 or 3 degrees to frame rake, and you have backed into 7 or 8 degrees of caster. And as others have said, measure off the kingpin top. Of course if you have adjustable spring perches it's easier to get the caster.
     
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  9. Lizzie deville
    Joined: Jun 21, 2021
    Posts: 3

    Lizzie deville

    Thanks for the replies. Very helpful
     
  10. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,212

    Elcohaulic

    What ever you do make sure you take your measurements with the car perfectly level, with each tire at the exact same spot or you will be chasing your tail.

    When I had my new driveway put in I had the guy make this one spot in the back as level as possible.
     
    Last edited: Jun 24, 2021
  11. clem
    Joined: Dec 20, 2006
    Posts: 4,188

    clem
    Member

    7* is what they are supposed to have.
    My sedan is 10* and the other car 7*.
    I would be comfortable with anything from 7* - 10*, but it should be 7*
     

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