Making a standard leaf pack into a metric ton

[Dando]

Would it be possible to have a spring shop make me the extra leaf I need to turn my 3+1 pack into a metric ton 4+1 metric ton pack. Then just add that leaf to my current pack?

[Incommando]

You could also just do an off the shelf add-a-leaf or any of the other ways to increase load capacity such as overload shocks. There would be no way to know what the end load capacity would be but I am pretty sure that is also true with aftermarket complete spring packs or with a custom add-a-leaf as you are asking about. 

[Eagle]

Would it be possible to have a spring shop make me the extra leaf I need to turn my 3+1 pack into a metric ton 4+1 metric ton pack. Then just add that leaf to my current pack?

The answer is obviously yes, since essentially the Metric Ton springs just have one more leaf than the standard springs. The tricky part is getting the proper thickness and arch to the added leaf so it increases carrying capacity without increasing ride height.

 

About three years ago a good friend picked up a well-used (actually, I guess abused is not so well used) '87 MJ. Each rear spring had a broken leaf in it, so he took the springs to a local spring shop to have the broken leaves replaced. He wanted the truck for hauling firewood (he heats his house with a wood stove), so he also asked to have an extra leaf added. Supposedly, he told the spring man he only wanted capacity, not lift.

 

Well ... he got lift. I never measured it, but according the Mark I, Mod 5 hairy eyeball the lift was at least 2 inches, and probably closer to 3". He was happy with that ... I would not have been.

 

I need to get an XJ spring under an MJ and hold it up next to the MJ spring. What I expect to find is that the unloaded XJ spring is going to have about the same arch as the installed MJ spring. If that's true, then it should be possible to add the XJ main leaf (with the eyes cut off) into the MJ pack without creating additional lift. But the extra leaf would add carrying capacity. How much -- don't know.

[Dando]

I would definetly like to avoid any unneeded lift, lifted truck just isn't my thing. Does anyone have any kind of spring rate or measurements etc of a disassembled metric ton leaf pack? I have a very good spring shop in akron that I want to discuss this with but I would like to have an idea of what I need from them before I even start talking with them.

[dybamx]

what about an overload spring? the kind that doesn't start working until the other leaves are compressed a certain amount?

[dybamx]

http://www.suspensionconnection.com/view-cat/jeep/comanche?category=helper%20springs

[HOrnbrod]

I need to get an XJ spring under an MJ and hold it up next to the MJ spring. What I expect to find is that the unloaded XJ spring is going to have about the same arch as the installed MJ spring. If that's true, then it should be possible to add the XJ main leaf (with the eyes cut off) into the MJ pack without creating additional lift. But the extra leaf would add carrying capacity. How much -- don't know.

Free arch will vary greatly depending on the XJ and MJ spring codes. On a side note, it's easy to see that installing MT springs on an MJ with the base leaf springs, you can expect a lift of 2"-3" depending on the MT spring you use.

 

MJ Springs: 7.62" - 9.50" Free Arch (Source: Hell Creek)

980 lb. capacity = 7.62" free arch, OEM part #89-52-002-312, 3+1 configuration

1100 lb. capacity = 8.75" free arch, OEM part #89-52-001-240, 3+1 configuration

1160 lb. capacity = 9.25" free arch, OEM part #89-52-002-351, 3+1 configuration

1220 lb. capacity = 9.75" free arch, OEM part #89-52-001-824, 3=1 configuration

1280 lb. capacity = 10.25" free arch, OEM part #89-52-002-350, 3+1 configuration

1440 lb. capacity = 9.12" free arch, OEM part #89-52-001-825, 4+1 configuration

1700 lb. capacity = 9.50" free arch, OEM part #89-52-003-676, 3+2 configuration

 

XJ Springs: 3-1/8" = 7.00" Free Arch (Source: JU Forum)

LL - 3-1/8" free arch, load rating 405

LM - 5-5/8" free arch, load rating 605

LS - 6" free arch, load rating 675

LT - 7" free arch, load rating 755 Up Country

 

Dealer part numbers:

 

52000050 Standard Duty, Coded LB

52000051 Standard Duty, Coded LC, EC

52000706 Standard Duty, Coded LN, ES

52000544 Heavy Duty, Coded LK

52000545 Heavy Duty, Coded LL, EL

52000707 Heavy Duty, Coded LM

52002390 Heavy Duty, Coded LS

52002392 Heavy Duty, Coded LT ( Up Country package +1” leaf spring)

[GrizzzzBear]

With the Tech Data from hornbrod, 

My Question is......

WHY does Everyone want to use a Clearly Inferior Component in the Rear Leaf Spring Package of a Comanche???

I mean Get a Grip on Reality!!!! Cherokee Springs are Not Even Close to Equal!!!!

 

IMO, Cherokee Leaf Springs are a Waste of Time & Money when used in a Comanche.

The Free Arch, Capacity & Length are All Way too far off to have an Equal Comparison.

[Eagle]

With the Tech Data from hornbrod, 

My Question is......

WHY does Everyone want to use a Clearly Inferior Component in the Rear Leaf Spring Package of a Comanche???

I mean Get a Grip on Reality!!!! Cherokee Springs are Not Even Close to Equal!!!!

 

IMO, Cherokee Leaf Springs are a Waste of Time & Money when used in a Comanche.

The Free Arch, Capacity & Length are All Way too far off to have an Equal Comparison.

 

Cherokee springs are clearly NOT "inferior" to Comanche springs. They are made to the exact same standards, and the leaves are the same steel and the same thickness. However, they are designed from the outset to be SOA, so they are designed to run basically flat at curb weight.

 

The concept is simple. As my structures professor expressed it in grad school, "Stress goes where there's material there to resist it." So ... add another leaf to a 4-leaf spring, and you increase the carrying capacity by 25 percent. Add another leaf to a 3-leaf spring and you increase the carrying capacity by 33 percent.

 

What you are griping about is just the arch. What happens if you add another leaf with the same unloaded arch is that you get more capacity but you also get lift. In an XJ, when a second set of main leaves (with the eyes cut off) is used as an AAL, it results in about 1-1/2 inches of lift. Do the same thing to an MJ using another pair of MJ main leaves, and you'll get about the same amount of lift, or maybe a bit more.

 

That's fine if you want lift, but what if (like me) you want the added capacity but DON'T want lift? The way you do that is to add an extra leaf that is arched as close as possible to the MJ springs when they are in the truck and sitting at curb weight. When you do that, the new leaf just takes up space, but isn't doing any work. However, as soon as you start to add load, now the new leaf is also deflecting, so it's adding carrying capacity.

 

I need to hold a loose XJ spring pack up under one of the MJs to see how close the arch is. I'm betting it's pretty close. If I'm right, XJ main leaves should make excellent MJ AALs.

 

But not if you want lift. Not everyone wants lift.