Shackels Questions

So I'm entering the final stages in gathering my lift components and I am now focusing on the rear. I'm going to build a bastard pack in the rear, but want to make it as flexible as possible. I've been told that shackels are the way to go to get the most articulation out of the rear (besides a coil conversion)

My goal is ~4 or so, but I am planning on "growing" the XJ to about 5.5 after I wear out my 31s, get an SYE, and regear. So my question is this, what shackel length and type should I get? Here is what I have been thinking about:

1.5" Teraflex Greasable
1" Lift Boomerang Shackles
1.5" Lift Boomerang Shackles
Rubicon Express Boomerang Shackles
1.25" Rubicon Express lift Shackles

Also what are the advantages for me getting a boomerang shackle?

Actually shackles help alot but are only part of the package to get the rear to flex well. You need to find a spring pack or main leaf that has some length to it, to get the shackle to sit around 45 degrees or so. This allows more movement for the leafs to droop and compress. I am in the process of designing a new shackle mount to move my attachement point forward to get a more desireable shackle angle. Right now I am running and RE 4.5" main leaf and thier shackle, and my shackle is straigh up and down, not the best irde of flex. But better than rusty's set-up. Do a little searching on the board and you would be surprised how many times this has been covered.

I too agree on searching, but it gives me an excuse to show what I did (CHEAP!!!).

Built new mounts that lower the mounting point. They are also moved backward.
I am using full F150 leaf packs, + 1 leaf, 5 leaves total. Sits about 6.5" or so.(note: these leaves are longer than stock, so new mounts are required.)

The shackle angle is near perfect now.


BEFORE Flex shot


AFTER Flex shot, it will droop even further once I relocate the shock mounts.

I forgot to mention, my reason for doing this was shitty flex from my bastard pack. The problem is if you use an XJ main, it will be too short to get the proper shackle angle once "arched" by the other leaves. Mine was actually angled toward the front causing a rough ride and limited flex. Sure I could have just made a mount lower and forward, but I wanted to run a longer spring, also for ride and flex.
It rides better in the rear than the front, but I'm running short arms....for now (hopeful winter project)

I got a set of 1.5" boomerangs from TNT and they worked out well.

Yeah, I searched but the results were pretty overwhelming, and I didn't get any hits for "boomerang advantages" or "boomerang purpose"

Thanks for the info, I think I see how it works now. Shackles + longer leafs = more flex

jdbwrx said:

I got a set of 1.5" boomerangs from TNT and they worked out well.

Click to expand...

x2, they're even greasable now

TRAILREADYXJ said:

I too agree on searching, but it gives me an excuse to show what I did (CHEAP!!!).

Built new mounts that lower the mounting point. They are also moved backward.
I am using full F150 leaf packs, + 1 leaf, 5 leaves total. Sits about 6.5" or so.(note: these leaves are longer than stock, so new mounts are required.)

The shackle angle is near perfect now.

BEFORE Flex shot

AFTER Flex shot, it will droop even further once I relocate the shock mounts.

Click to expand...

what is the length eye-to-eye of the F-150 main leaf? loaded, preferably. Thanks

i agree that the longer leaf swap was definitly worth the benefits. I used an MJ leaf.

splitz said:

Yeah, I searched but the results were pretty overwhelming, and I didn't get any hits for "boomerang advantages" or "boomerang purpose"

Thanks for the info, I think I see how it works now. Shackles + longer leafs = more flex

Click to expand...

The boomerangs allow better clearance, which in turn should equal better flex. Someone correct me if I am way off on that.

did you use the new body style f150 or like say a 2000 f150?

jdbwrx said:

The boomerangs allow better clearance, which in turn should equal better flex. Someone correct me if I am way off on that.

Click to expand...

boomerang shackles only help with clearence of your usin full lift packs since they have a longer main leaf, if your usin a stock main leaf then a regular shackle is fine

jjvande said:

what is the length eye-to-eye of the F-150 main leaf? loaded, preferably. Thanks

i agree that the longer leaf swap was definitly worth the benefits. I used an MJ leaf.

Click to expand...

I am not positive on the length, I can measure an extra spring we have at the shop if needed. The centering pin is normally too far back (about 1.25"), and would require a new front mount unless you do what I did. Since my 8.25 has 3 holes in the perch, I just moved the axle forward, so the pin goes in the rear hole. I actually made shims with an offset hole as well, the pinion pointed way too high without. This turned out to be about perfect for stuffage. I decided to do this instead of building a new mount to allow me to move the axle back in the future to run a longer WB. Eventually I plan on caging it, chopping the rear quarters, swapping axles and running 36 or 37s.

2000xj4x4 said:

did you use the new body style f150 or like say a 2000 f150?

Click to expand...

I am not too sure what year, but Id guess 90s. We bought several packs for bastard packs and such, they were all in a pile out of the truck. They were 4 leaf packs with an overload. I ended up using 5 leaves (all f-150) and ditched the overload.

ROBZ95Xj said:

boomerang shackles only help with clearence of your usin full lift packs since they have a longer main leaf, if your usin a stock main leaf then a regular shackle is fine

Click to expand...

Semi-true, Boomerangs can help fit many spring packs since they can be flipped to allow the most movement in the "pocket" (stock shackles have little movement, any longer shackle will move more, giving more flex). The problem is they do absolutely NOTHING to correct actual shackle angle. The ONLY way to do that it my moving the mount, or using the correct length main leaf. Boomerangs are designed to fit a longer spring in most applications so the shackle can pivot backward farther in the pocket, not forward. Draw an imaginary line between the mounting bolts to figure the angle. A lot of control arms are bent for clearance, but it doesn't change the angle. If that were the case there would be no need for longarms and such.

With the shackle angle pointing to the front like /, the shackle has to move down and back as the spring compresses. Spring wanting to go up, shackle wanting to move down...so they fight each other.
With it angled to the rear like \, the shackle is free to pivot up and back so it doesn't fight the movement of the spring pack.
Straight up and down isn't ideal, mainly for droop, since the shackle will pull down and forward as the spring droops. The more you can utilize the "natural" range of the shackle, the better it will ride and flex.

Here is a side shot of mine flexed out to show the shackle movement in action. Notice the compressed spring pack is nearly flat with plenty of room for the shackle to move (limited by bumpstop), the drooped side shackle still has room to move forward, I can (and will) relocate the shock higher to allow it to droop further.

TRAILREADYXJ said:

Semi-true, Boomerangs can help fit many spring packs since they can be flipped to allow the most movement in the "pocket" (stock shackles have little movement, any longer shackle will move more, giving more flex). The problem is they do absolutely NOTHING to correct actual shackle angle. The ONLY way to do that it my moving the mount, or using the correct length main leaf. Boomerangs are designed to fit a longer spring in most applications so the shackle can pivot backward farther in the pocket, not forward. Draw an imaginary line between the mounting bolts to figure the angle. A lot of control arms are bent for clearance, but it doesn't change the angle. If that were the case there would be no need for longarms and such.

With the shackle angle pointing to the front like /, the shackle has to move down and back as the spring compresses. Spring wanting to go up, shackle wanting to move down...so they fight each other.
With it angled to the rear like \, the shackle is free to pivot up and back so it doesn't fight the movement of the spring pack.
Straight up and down isn't ideal, mainly for droop, since the shackle will pull down and forward as the spring droops. The more you can utilize the "natural" range of the shackle, the better it will ride and flex.

Here is a side shot of mine flexed out to show the shackle movement in action. Notice the compressed spring pack is nearly flat with plenty of room for the shackle to move (limited by bumpstop), the drooped side shackle still has room to move forward, I can (and will) relocate the shock higher to allow it to droop further.

Click to expand...

Great explanation thanks. So what's the ideal lenght for the main leaf when using boomerangs? I would think it would be the distance from eye to eye of the shackel when they are at their most horizontal angle.

The reason I ask is I have a set of Toyota pickup leafs that are long, and just might be the right width. I'm wondering if they would work with the boomerangs.

well, you would just have to measure the toy leaves and see, they should be the same width, but you would have to check on the centering pin measurment too, not just total length.

There is no set "ideal length" for boomerangs, it all depends on the amount of lift in the pack. The main thing is you want the shackle around 45* to the rear when loaded and level. Once again, boomerangs just allow more rearward movement of the shackle in the pocket (helpful with the stock design of the hanger pocket). The angle would be the same with a normal shackle, it would just bottom out on the crossmember before a boomerang would.

what and all did u buy to do this lift, i would like to have it on mine. i know u got the f150 rear springs, but what other stuff did u buy such as coils, u-bolts...

Well, the front is mostly Rusty's stuff, 4.5" Coils w/spacers, Adj, LCAs, and track bar. The UCAs are modified stock arms. I am also using YJ brake lines, with the hard line relocated.

As far as the rear goes... the hardest part to duplicate would be the custom offset shims I made. The U-bolts can be found at NAPA or other parts stores. I have an 8.25 that has 3" tubes, so it was easy to find the right size. Dana axles use odd sizes and can be harder to find (something like 2.65"???). Other than that it's just 1/4" plate, and some box tubing cut open and gusseted. Oh, and I used the F-150 shackles too, they are almost identical to MJ shackles.

i hav s-10 bastard packs and homebrew 1 in shackles. can i just drill a new hole in the pocket to move it forward and correct my shackle angle which is straight up and down. it looks like their should be enough room to move it forward...???

troy6187 said:

can i just drill a new hole in the pocket to move it forward and correct my shackle angle which is straight up and down. it looks like their should be enough room to move it forward...???

Click to expand...

The shape of the pocket won't really allow this, it is narrower where the shackle bolts up. There is also no access to the inside to put a nut on the bolt.