New leaf pack inverted/negative arch?

4901 Views 40 Replies 10 Participants Last post by virshereads, 5 mo ago

tuxj

Discussion Starter · Aug 11, 2021 (Edited)

Hey team,

I just noticed this while the Jeep was on the lift getting exhaust work done. My new leafs seem to be arching over the axle to form a “W/ Mustache” shape, as opposed to a “U” shape. (This is a drive-on lift at the shop, as opposed to a frame lift, so it sits as it would on the road).

It’s IRO 3.5” packs, IRO 1.5” Boomerang shackle, Iron Man Shackle Relocation Brackets.

I reached out to IRO and they think it’s caused by the relocation brackets and recommended removing them.

Only thing I realized during installation is I installed pack onto axle first, then lined up front and rear bushings. Would installing ends first, and then securing to axle be any better?

Here are some photos.

Thanks!

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tuxj

Discussion Starter · #2 · Aug 12, 2021

Here is a photo of the shackle angle with the relocation brackets.

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quicksilver

· #3 · Aug 12, 2021

Your logic on the order of installation seems to make sense to me... I'd bolt both ends of the leafs into place first, then secure the u bolts on the axle perch. Of course, if you just loosen up the nuts on the u bolts, you wouldn't have to worry about undoing the leaf spring bushings.

It still seems odd that the leafs would arch the way they are regardless of the order you did it in. I doubt the relocation brackets will do that either. The steeper angle is putting less downward force on the end of the leaf and pushing it out more toward the back...

tuxj

Discussion Starter · #4 · Aug 12, 2021

The other thing IRO brought up is weight. I’m not sure what would be considered a lot for an XJ, but I have an empty roof rack, IRO gas tank skid, and cargo area has 33” spare and a collection of tools, Jack, fluids, etc.

I didn’t think that would be enough to do this to a brand new leaf pack.

Guess I’ll be emptying the Jeep and pulling the relocation brackets just to determine if there’s an issue with the spring packs. Which sucks, since the brackets were a pain to get bolt holes lined up with tow hitch and skid plate.

The ride is excellent right now, but I don’t want to let it go like this if it’s going to fail or cause issues eventually, since I doubt IRO would be much help after much time has passed after installation.

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4.3L XJ

· #5 · Aug 12, 2021

OK, now for my 2 cents. First I will tell you that I used to design and build lift kits from scratch in the 70s, until Rancho put me out of business with Chinese stuff. I have also worked briefly in a spring foundry. So here it is.

I see two things wrong here. First the middle of the spring is not supported enough and all the bending is there. Eventually, this spring will sag as it will loose the temper there from being bent too far.

Second, I am going to trash some internet conventional wisdom. It is a popular thing to put the shackle at the angle you have there, and you obviously bought a kit for that purpose. However the reason they soften the ride is that they make the spring bend exactly as you have shown here (Thanks for the pics on this). The spring bends in an unnatural way and only bends on one spot instead of all over so the ride is "softened". Now I can find probably a hundred guys on forums that will disagree with me on this, but the proof is in the pics.

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tuxj

Discussion Starter · #6 · Aug 12, 2021

4.3L XJ said:
OK, now for my 2 cents. First I will tell you that I used to design and build lift kits from scratch in the 70s, until Rancho put me out of business with Chinese stuff. I have also worked briefly in a spring foundry. So here it is.

I see two things wrong here. First the middle of the spring is not supported enough and all the bending is there. Eventually, this spring will sag as it will loose the temper there from being bent too far.

Second, I am going to trash some internet conventional wisdom. It is a popular thing to put the shackle at the angle you have there, and you obviously bought a kit for that purpose. However the reason they soften the ride is that they make the spring bend exactly as you have shown here (Thanks for the pics on this). The spring bends in an unnatural way and only bends on one spot instead of all over so the ride is "softened". Now I can find probably a hundred guys on forums that will disagree with me on this, but the proof is in the pics.

Thanks for your thoughts. What would be the remedy for the leaf spring support issue you mention?

Perhaps moving the shackle back a bit on the bracket may help then. That’s easy to experiment with.

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4.3L XJ

· #7 · Aug 12, 2021

I would need to see a little better pic of the center of the spring, but the addition of a short leaf might solve the problem

Gluckmysock

· #8 · Aug 12, 2021

I installed no lift shackle brackets and boomerang shackles with 3.5" RE leafs. I wound up with 4.5"+ of lift and kept about 200 lbs of extra wait to get them to settle. But they never looked like that. Unless you have the rear extremely overloaded, I agree with 4.3.

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tuxj

Discussion Starter · #9 · Aug 12, 2021

Am I crazy, or does their website photo of these springs also have a slight inversion to them in the center?

XJ 3.5" Leaf Springs - Iron Rock Off Road

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Gluckmysock

· #10 · Aug 12, 2021

Yep. Looks that way to me!

4.3L XJ

· #11 · Aug 12, 2021

Yup I think so too. This just means they use an adjustable table that doesn't have a good center adjustment. However I still stand by having a shorter leaf added to the center. That bottom leaf is too long IMO

tuxj

Discussion Starter · #12 · Aug 12, 2021

4.3L XJ said:
Yup I think so too. This just means they use an adjustable table that doesn't have a good center adjustment. However I still stand by having a shorter leaf added to the center. That bottom leaf is too long IMO

Would you be talking about something like a short add-a-leaf?

www.rustysoffroad.com

Rusty's Add-A-Leaf - 1.5" Short (pair)

Rusty's add-a-leafs are an inexpensive way to add lift to your vehicle. These leafs are positioned within the existing spring pack and add more arch to the springs. They also help restore ride height lost from sagging springs and bump up the spring rate to handle the additional weight from a...

www.rustysoffroad.com

What would be the pitfalls of running springs like this in the event IRO doesn’t play nice? That add a leaf is a cheap thing to try. Otherwise I’ll just have to run them until they sag enough to replace with BDS or something of better quality.

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4.3L XJ

· #13 · Aug 12, 2021

What I would do, is instead of adding a curved leaf, which would stiffen your ride considerably I think, is use a flat tapered leaf about the length of the last leaf, then remove it and use the flat one. This would give you a two stage spring that should have a ride about like what you have now and the center would be supported

tuxj

Discussion Starter · #14 · Aug 12, 2021 (Edited)

4.3L XJ said:
What I would do, is instead of adding a curved leaf, which would stiffen your ride considerably I think, is use a flat tapered leaf about the length of the last leaf, then remove it and use the flat one. This would give you a two stage spring that should have a ride about like what you have now and the center would be supported

Any chance you would have a link of what you’re referring to? All I seem to find are curved add a leafs.

And what would be the long term theory of what would happen by running springs like this without adding anything?

Edit:
This is what IRO would have me use to add to my pack:

IRO 3.5" Leaf Spring Add-A-Leaf - Iron Rock Off Road

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Gluckmysock

· #15 · Aug 12, 2021

I understand what 4.3 is saying. That pack was assembled with ALL curved leafs. They are pressed together then the center bolt is installed. because the bottom leaf is so long and curved, it actually presses up on the leafs on top and this is what causes that wonky shape. If you remove the bottom leaf and replace it with one the same length, but flat. It will take out the wonkyness. Here is a leaf pack from clayton off road and you can see how flat the bottom leaf is.

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tuxj

Discussion Starter · #16 · Aug 13, 2021

Gluckmysock said:
I understand what 4.3 is saying. That pack was assembled with ALL curved leafs. They are pressed together then the center bolt is installed. because the bottom leaf is so long and curved, it actually presses up on the leafs on top and this is what causes that wonky shape. If you remove the bottom leaf and replace it with one the same length, but flat. It will take out the wonkyness. Here is a leaf pack from clayton off road and you can see how flat the bottom leaf is.
View attachment 229691

Thanks for the photo, I see what you mean. Having trouble searching for a flat leaf to use. All my searches for flat leaf spring bring up endless forum results of people experiencing decades old leaf packs being flat.

I guess when it comes down to it, I really just want to know if this will even cause issues or if it just visually looks weird. The lift height and ride is stellar, so not totally eager to mess with it. On the flip side, I don’t want it to cause issue on the trail or totally sag in a month.

4.3L XJ

· #17 · Aug 13, 2021

tuxj said:
Any chance you would have a link of what you’re referring to? All I seem to find are curved add a leafs.

And what would be the long term theory of what would happen by running springs like this without adding anything?

Edit:
This is what IRO would have me use to add to my pack:

IRO 3.5" Leaf Spring Add-A-Leaf - Iron Rock Off Road

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The best place to get that leaf would be at a pick and pull. There are tons of them on rear springs in a wrecking yard, and they would be cheap. One off an S10 would be ideal and if you were local to me, I probably have some sitting in the scrap pile

tuxj

Discussion Starter · #18 · Aug 13, 2021

I experimented with moving the shackles back one hole on the shackle relocation brackets. Not much, if any, difference in the springs or the ride.

Took some photos while leafs were at full droop and shackle bolts loose. Sorry for the dark lighting; had to start working on it at 4:30am to beat the triple digit heat outside!

And here is how it looks with vehicle weight on them, in the new position on the SRB.

I’m really torn about putting any money into these. I want a solid rig, but I also am happy with the ride and height. So if it’s not going to get worse or cause issues, I think I’d roll with it. I dunno. lol

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tuxj

Discussion Starter · #19 · Aug 13, 2021

4.3L XJ said:
The best place to get that leaf would be at a pick and pull. There are tons of them on rear springs in a wrecking yard, and they would be cheap. One off an S10 would be ideal and if you were local to me, I probably have some sitting in the scrap pile

Hey 4.3, in this picture of an S10 pack I would be looking at the flat leaf on bottom right?

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4.3L XJ

· #20 · Aug 13, 2021

You got it.

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