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Shackle angle?

Discussion in 'The Garage' started by camok5, Dec 14, 2005.

  1. camok5

    camok5 1/2 ton status Premium Member

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    I have seen a bunch of threads lately talking about changing your shackle angles to get better flex and ride and I want to know how big of an improvment it is? Both my front and rear shackles are straight up and down, is this bad? What is the best angles to run and is there any negatives to changing them? Also it seem that alot of the people doing this are the ones running longer springs, is there a reason?
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    There is no specific "right" shackle angle. Determining what is best for you depends on lots of things. Spring rate, shackle length, vehicle weight, arch, and travel range are among the big things.

    But generally, for a compression shackle, on most vehicles, with typical after market lift springs, you will want the fixed end of the shackle to be somewhat closer to the fixed end of the spring than the shackle end spring eye. That means that the top of the shackle is angled toward the front of the truck. This will reduce your spring rate a bit, and is particularly useful if you have stiff springs like Rough Country. A longer shackle is also generally better due to the flatter arc of the swinging end, as long as you don't go overboard and cause problems for alignment and pinion orientation. But too much angle will cause physical interference with the frame on compression (or other limits due to geometry) and may lead to too low of a spring rate. There are lots of things to consider.

    But the biggest problem typical of GM lifts is that the short front shackle is actually set so that the spring eye is *forward* of the frame mount, so that when you droop that side, the shackle lines up with the arch of the spring fairly quickly, limiting movement in the process. It also fight compression of the positive arched springs by effectively increasing the spring rate and jacking the body by forcing the spring eye downward as it moves back (as it must to compress the arched spring).

    Searching for exact phrase "shackle angle" will get you lots of posts on the subject.
     
  3. camok5

    camok5 1/2 ton status Premium Member

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    Has anyone with stock length springs changed the angle of their shackles and did it make a differance?
     
  4. az-k5

    az-k5 1/2 ton status

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    I did with some standard 4" BDS front springs. Raked it about 20° and noticed a much better ride and about 3-4" of more flex. My rear shackle is set around 40° and you can barely feel it go over a bump.
     
  5. camok5

    camok5 1/2 ton status Premium Member

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    Just looked at your pics and have you ever hit your rear leafs with the shackle because they looked like they could?
     
  6. az-k5

    az-k5 1/2 ton status

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    They just barely clear. The paint is still there so there is no contact.

    This is about max flex. I do have bump stops and clear my flatbed by less than 2"

    [​IMG]
     

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