• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Adjustable shackle and relocators

Black1990jeep

NAXJA Forum User
Location
california
On my 1990 XJ I have 33 inch tires and a Rubicon 5,5 inch lift. My shackles are five inches long. I installed the lift shackle relocator kit from iron man. The shackles at first I put in the center hole in the relocator bracket, got me near 45 degrees, but it dropped my jeep body too much such that wheels rubbed on the flares. So I moved the shackle to the rear most hole in the relocator bracket. This improved lift, but not as much as I liked, but gave me a 10 degree shackle angle, better than what I had before (before the relocator, the shackle was vertical, and ride was harsh.)

So I want to go to a shackle length to give me a 45 degree angle and up my lift a bit more for added tire clearance.

I see iron mans adjustable shackle, it has a range of adjustment from 8 to 10.5 inches.

I have kind of sketched out the geometry on paper with a protractor and ruler and think that 8 inch shackle would give me close to 45 degree angle if I use the forward most hole of the relocator, and it looks like it would give me near 3/4 inch of lift too.

Does this seem correct?

Core offers a shackle that goes from 5 to 8 inches, verses ironman that is 8 to 10.5 adjustment range.

So should I go with the iron man shackle, which may even allow more lift is say I adjust it to 9 inches?

As for angle Is it true that 45 degrees is the best? what if it is steeper, say 30 degrees ie more vertical than 45 degrees, is used? will that cause trouble?

I think I can also swap the shackle relocator around to allow even more forward holes, for even longer shackle while able to keep a good near 45 degree angle, right?

Advice?

Thanks
 
One thing to also take into consideration is the amount of lift that you get from a shackle is only 1/2 that of the length of the shackle, so even if you go from your 5" shackle to an 8" shackle - The maximum amount of lift a 3" shackle will provide even in a vertical plane- is 1.5" of possible lift. You are correct that you can actually decrease the total amount of lift by decreasing angle of the shackle - which in your Pythagorean Theorem c2 = a2 + b2 (2 denotes to the power of) that you messed with earlier and assume c2 is the length of your shackle a2 is your vertical height and b2 is the horizontal from the shackle mounting point to the leaf mounting point in a horizontal plane, you are increasing the horizontal b2 as you decrease the shackle angle and in turn decrease your a2 vertical height if you keep your shackle length constant c2. Bottom line, even with a 3" longer shackle you are going to get less than 1.5" of total lift. If I did the math correctly and at a consistent 45 degree angle a 3" longer shackle will net you 1.06" of lift. - Hope that helps?
 
Last edited:
Mine's currently at 45°, so I'm not one to talk, but I'm not happy with it and was going to increase it. While searching for a technical answer to your question, I found this thread particularly convincing

https://www.jalopyjournal.com/forum/threads/leaf-spring-shackle-angle.682051/

At the end of the day, shock travel is typically the limiting factor on droop, so maximizing your ability to flex doesn't really provide any benefit. That being said, some of us build trail only rigs, some of us build race trucks. If you're building a trail rig, run 45°, you'll be happy with it. If you're building a Tow/Winter/back-up DD rig, you won't be.

I had to trim the bracket rearward of the hole I used; that was the main reason for shifting it forward. It also makes it possible to increase the angle to lift the suspension as new leafs settle in.

Bajabronco, on a side note, you're math is a little off. The length of any two legs of triangle added together must be greater than the length of the third.
 
Jim, I think my math is correct. - If you look at the 8" shackle - which is the long side of the triangle - and he had a 5" long shackle to start with, then the increase in length of the hypotenuse is 3". So if we know the angle is 45 deg, and we are looking at a right triangle, then the initial height of the triangle is 3.53", and then the height is increased to 5.65" with the new 8" shackle - so keeping the angle the same, in going to a 3" longer shackle will give an increase in the height of 2.12" (new height of 5.65 - previous height of 3.53) The thing is when using a lift shackle you are only increasing the overall height of the rear end by 1/2 of the actual number (you are only lifting one side of the leaf spring) so 2.12 (.5) = actual lift amount of 1.06"
 
Back
Top