MJ rear SOA?

I'm getting ready to put the axle under the rear and have a question, are there different stock leaf packs for the MJ? Mine only has 4 leafs and one is a thick (about 1" in the middle) overload leaf. I'm going to throw in some stock XJ leafs and ditch the thick overload leaf. Thoughts?

I wouldn't get in a big hurry to ditch the overload. My packs have a thick overload on the bottom, and I love them. They act as bumpstops, to keep my packs from over flexing, and they also help to resist axle wrap. I say keep them, and if you aren't happy with the stuffage, then remove them, but I am happy with mine. .02

I ran the overload on my MJ SOA and I loved it. I mixed in CJ lift springs though also to get a little more arch out of the packs. I would think the XJ packs are too flat for the MJ packs to really do any good or anything at all. You might find at full droop and no spring clamp that the XJ leaves will actually have space between them and the main leaf, but I am not sure or not if that will happen. MJ stock packs SOA flex awesome though, why are you thinking of adding XJ leaves mixed in?

HEEPJEEP said:

I ran the overload on my MJ SOA and I loved it. I mixed in CJ lift springs though also to get a little more arch out of the packs. I would think the XJ packs are too flat for the MJ packs to really do any good or anything at all. You might find at full droop and no spring clamp that the XJ leaves will actually have space between them and the main leaf, but I am not sure or not if that will happen. MJ stock packs SOA flex awesome though, why are you thinking of adding XJ leaves mixed in?

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Good to hear they flex well in stock form. I was considering ditching the overload leaf and didn't think a 3 leaf pack was going to do to well, that is why I am considering the XJ Leafs. Besides, usually more thiner leafs performs better then fewer thicker leafs. I may hold off on the XJ leafs and see how it does SOA with the stock packs.

The stock mj springs will die a quick death without the overload. You will have massive axlewrap and they will sag almost instantly. I have run 5 different configurations of leafs on the rear of my mj. The best ride/flex came from a mj pack where i doubled up the second longest leaves and removed the overload. This configuration would hit the bumpstop in stock location and droop like no other. They would flex way into a negative arch. Worked great for crawling, but i killed them fast doing some high speed desert stuff.

right now im running a comanche main leaf, two f-150 leafs, a comanche leaf, and the f-150 overload. Works pretty good, tons of droop because the f-150s have more arch than the mj's, but they are a little stiff as far as uptravel goes. Im going to try and add another long leaf in to ditch the overload to get a little more uptravel.

MJlogan said:

The stock mj springs will die a quick death without the overload. You will have massive axlewrap and they will sag almost instantly. I have run 5 different configurations of leafs on the rear of my mj. The best ride/flex came from a mj pack where i doubled up the second longest leaves and removed the overload. This configuration would hit the bumpstop in stock location and droop like no other. They would flex way into a negative arch. Worked great for crawling, but i killed them fast doing some high speed desert stuff.

right now im running a comanche main leaf, two f-150 leafs, a comanche leaf, and the f-150 overload. Works pretty good, tons of droop because the f-150s have more arch than the mj's, but they are a little stiff as far as uptravel goes. Im going to try and add another long leaf in to ditch the overload to get a little more uptravel.

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Not trying to hijack this thread, but how much lift does the above setup give you?
Buck

MJlogan said:

The stock mj springs will die a quick death without the overload. You will have massive axlewrap and they will sag almost instantly. The best ride/flex came from a mj pack where i doubled up the second longest leaves and removed the overload. This configuration would hit the bumpstop in stock location and droop like no other. They would flex way into a negative arch. Worked great for crawling, but i killed them fast doing some high speed desert stuff.

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You have confused me (not that hard). You say the stock set up is best and my springs will die fast if I do other wise, then you discribe your best setup which was not the stock setup.... Which is it........
I didn't plan to run the stock springs with out the overload. If you read my post, I planned to add XJ leafs to make up for the overload spring.....

I agree with HeepJeep -- XJ springs are flatter than MJ springs, so I think you'll be losing ground if you try to use XJ leaves in an MJ pack. The XJ springs are also 5" shorter, and that ain't gonna help.

I'd suggest scrounging for Dakota leaves, or YJ leaves. I was given set of YJ springs by a friend who did a lift install for someone and needed to get the old parts out of his basement. On my garage floor they have a bit more arch than a set of XJ springs. The owner of the YJ apparently used it rather hard pre-lift, too, because when I inspected the ones that weren't totally smashed (from when he hit the tree), the ends of the main leaves are actually bent slightly down right at the point where the second leaves end. Which tells me that for durability you want the longest possible second leaf you can get, and if you can find something that'll be TRULY "full length" you're way ahead.

You can improve droop somewhat by using only two rebound clips, and keeping them fairly close to the axle. If they're tight they'll keep the leaves aligned, but the ends of the leaves can still spread vertically when the spring is unloaded.

I think I'm getting pretty good axle wrap now that I'm running the 9". What effect would adding a MJ overload leaf have? Would I gain 1" of lift in the rear and reduce axle wrap? Would it limit flex? [/hijack off]

My 89 MJ Metric Ton came with 5 leaves: 3 'normal' ones bound by the spring clamps, 1 long (3' long X .500" thick apprx.) overload and 1 short (2'L X .625"thk. apprx.) overload. The long overload has a small bit of arch and the short one was flat.

When I first did the SOA, I used all five leaves, but quickly got rid of the short overload. IIRC it was mainly to lower the rear ride-height. With 33x12.5 the flex was great. In actual trail use (opposed to a ramp...I never 'ramped' that MJ) the leafpack could get flat... but not into negative arch that I could tell - the stuffed tire would limit that.

I had considered not running the longer overload since I was still sitting butt-high (just run the three main leaves) but everything worked very well with the 3+1 so I left it be. In 3 seasons of abuse, the springpacks never sagged out.

<edit> Eagle has good advice about moving the clips closer to the axle tube... I removed the rear clip on my packs, but retained the front ones: The overload leaf needed to get kicked/sledged back into alignment once in awhile...but in vactory configuration, the Overload leaves were never held captive by the clips anyway<edit>

If axlewrap is too much for ya to stand, build a traction link

Hmmm something must be different about my stock leafs. The spring clips are the type that are bolted to one leaf and then run up above the other leafs and has a bolt/nut through the top. I can not move these.

If your leaf springs are odd JnJ, then the ones I had on my MJ were odd too. IIRC, it had a 3 leaf pack with overload and the clamp was riveted the the bottom leaf (not overload) about halfway between the axle and the end of the pack.

Sorry I cannot add any constructive input cause I working at building my first leaf pack for my XJ. I sure am "absorbing" everyones input though. Thanks!

Les

JnJ said:

Hmmm something must be different about my stock leafs. The spring clips are the type that are bolted to one leaf and then run up above the other leafs and has a bolt/nut through the top. I can not move these.

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Well then... I just peeked at the clamps on my 87 SWB and they are just like you describe. OTOH the 89 LWB are riveted(?) to the bottom leaf and just wrap around over the top of the top leaf like this [_] )

Thanks JnJ... I'm getting my PT this morning walking to my Jeep graveyard & back for ya

woody said:

Well then... I just peeked at the clamps on my 87 SWB and they are just like you describe. OTOH the 89 LWB are riveted(?) to the bottom leaf and just wrap around over the top of the top leaf like this [_] )

Thanks JnJ... I'm getting my PT this morning walking to my Jeep graveyard & back for ya

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No problem, just doing my part to keep ya healthy. I'm going to run the stock pack SOA and see how it does.

JnJ said:

Hmmm something must be different about my stock leafs. The spring clips are the type that are bolted to one leaf and then run up above the other leafs and has a bolt/nut through the top. I can not move these.

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Correct. MJ springs have that type of clip and YJ springs have that type (YJ are riveted and the vertical legs bent over at the top -- no thru bolt). As you know, the XJ springs use the sheet metal wrap-around type.

The MJ clips aren't bolted onto the leaf, they're riveted. If you're building your own custom packs you can either cut/grind them off, or you can extend the two vertical arms and move the bolt up. That'll keep your springs aligned but give you room to flex.

I was assuming you'd blow off those clips if you're going to be adding leaves.

Sorry about the confusion

-stock setup- not the best but works pretty darn good

-Best setup (so far) for flex that i have come up with is the stock comanche pack minus the overload leaf. heres the rundown in order:

1.stock comanche main leaf
2.stock comanche long leaf
3.ANOTHER stock comanche long leaf
4.stock comanche leaf with clamps no bolts in clamps
5.no overload

Insane amounts of uptravel- will hit the stock bumpstop in the stock location. Gives around 6.5" lift. I bent all of the leafs doing stupid high speed stuff in the desert. as long as your not an idiot like i am it will last.


Blue Jackson:
The f-150 springs make it sit perfectly level with my 4.5" zj coils, a 1.75" spacer and 2 stock isolaters stacked up front. im guessing around 8" lift. This is also with a 35" spare in back and about 150lbs of tools and spares. Stuffs the 35's pretty good, but its a little on the stiff side. The leafs still flex into a slightly negative arch, but wont hit the stock bumpstop like the combo above. rundown on the f-150 pack:

1. stock mj main leaf
2. f-150 long leaf
3. f-150 second longest leaf
4. stock mj leaf with clamps (no bolts through clamps)
5. f-150 overload

I think the f-150 pack minus the overload would be an ideal setup for around 7" lift. I'll try to post up how this works as i am lowering my mj 2" in the next few weeks.

JnJ-
Got ya on the xj springs- missed that part, sorry. I'd add in the longest leaf you can to the pack. I think the longest xj leaf will be slightly shorter than the longest mj leaf. Im referring to the normal leafs not main leaf with eyes.

well, i probably confused you guys even more. im horrible at trying to describe this stuff. let me know if i helped at all....

JnJ --

Maybe this will help guide you:

Rancho sells the same long AAL for both the XJ and the MJ. They list it as 2-1/2" for both, which is impossible. So I called their tech support number to ask what's the right number for each. Gal says "2-1/2" ". After I explained why that's not possible, she said "Uh ... just a minute."

She obviously went to talk to someone who knows something, because she came back (more than a minute later) to say it's 2-1/2" in the XJ and 1-1/2" in the MJ.

For comparison, taking a second XJ main leaf, cutting off the eyes and using it as an AAL in an XJ yields about 1-1/2".

Extrapolating, if the same Rancho AAL provides 1" more in an XJ, and an XJ main leaf provides 1-1/2" in an XJ, that same XJ main leaf in an MJ isn't good for much more than about 1/2"

I just added a leaf to my long bed MJ trailer since any load in the thing would really squat it down. I used a Bronco II main leaf with the loops cut off with a torch. It sits under the main leaf of my stock MJ pack and goes right up to the eyes (ok, maybe just a tad shorter to allow for length change as it cycles.) I removed the two spring clamp bolts, but left the U shaped uprights. I'm not going for flex though, but this is a way to get a full length second leaf with close to the same arch. I also added shocks to the trailer and that was the BEST thing I've done to it yet. A load would make the trailer sway on the springs something terrible since they were so soft. It would track straight behind my xj, but the bed would rock side to side. The shocks pretty much eliminated that. Jeff

I thought I should chime in with a picture on my almost stock MJ leafpack in SOA. I added a second main leaf to each side (after cutting the eyes off) and kept the overload leafs. The extra leaf was added to gain some load carrying capability (I don't want the ass-end saggin after loading the truck up for an outing) and to help fight axle wrap. The 33incher stuffs without touching the flares (in a static mode). Before I get out on the trails again (after an engine transplant) I will extend the bumpstops, but as of right now the stock ones don't even come close to touching and the springs do all the limiting on their own.
Jeep on!
--Pete