Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

HD front shackle

Discussion in 'OffRoad Design' started by Mastiff, Aug 2, 2003.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

    Joined:
    Jul 21, 2002
    Posts:
    2,755
    Likes Received:
    48
    Location:
    Tucson, AZ
    Can you explain what happens to the extra half inch of lengh on the shackle? Does the front end sit slightly higher, or does the shackle tilt back a little more than stock? A combination of the two? I'm just asking because I can't really picture the physics of it to predict how it works. /forums/images/graemlins/tongue.gif

    The web page mentions that it affect caster angle and may influence the amount of highway wander. It tilts the pinion down then? Funny thing is, I have a shim in there to tilt it up. But I do wander some on the highway.
     
  2. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    Now this is an exaggeration, but for the sake of explaining, think about putting a shackle 1 foot longer than stock back there. What would happen would be that the rearmost part of the spring would be pushed downward, the pinion would be pointed downward more (caster increasing), and you would gain roughly 6" of lift. This six inches is the result of only moving one half of the front spring down 12 inches. *Disclaimer; do NOT put a shackle more than about 1-2" longer than stock in!*

    Anyway, that's basically the physics of it. With only 1/2" difference, it's not going to change caster too much and the shackle will still be relatively straight up and down. The reason for the little bit of extra length is to keep the spring eye from hitting the frame when the leaf spring flattens while stuffing a tire.
     
  3. Mastiff

    Mastiff 1/2 ton status Premium Member

    Joined:
    Jul 21, 2002
    Posts:
    2,755
    Likes Received:
    48
    Location:
    Tucson, AZ
    Thanks, that makes sense. /forums/images/graemlins/thinking.gif
     
  4. Z3PR

    Z3PR Banned

    Joined:
    Mar 30, 2002
    Posts:
    19,217
    Likes Received:
    0
    Location:
    Everywhere
    But do you gain 1/2 a inch of lift ??? I was under the impression you do.
     
  5. 84k5

    84k5 1/2 ton status

    Joined:
    May 13, 2000
    Posts:
    2,949
    Likes Received:
    0
    Location:
    Dublin, CA
    You only gain half of the increase in shackle length. So in this case you get 1/4" of lift.
     
  6. bigjbear

    bigjbear 1 ton status Staff Member Moderator

    Joined:
    Feb 18, 2000
    Posts:
    13,973
    Likes Received:
    453
    Location:
    Marietta GA
    If it's 1/2" longer you gain 1/4" of lift. You are only moving the mount point of one end of the spring.
     

Share This Page