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Spring-over with metric tone

billyjp2

billyjp2

NAXJA Forum User
Location
Indian Orchard MA
I recently aquired a 2wd MJ that has 4wd metric tone rear leafs swapped into it. If I do a spring over, how much lift am I looking at needing for the front. I would appreciate people who have done something similar to this giving me an idea of what worked for them. I'd like to keep it at around 4.5" as I'll be putting on 33s.

Thanks in advance
 
Take your height now, and add:

Height of the sprung-under perch
Axletube diameter
Height of the spring-over perch

That should give you an idea of where it will sit. You'll probably gain around 4" by just going sprung-over.
 
Plus axle tube diameter of the 8.8 you want to put in will add a little as well. I'm betting you could easily get away with an extended shackle if you didn't mind SUA. Relocate the shock mounts onto the axle, run the shocks that are on it and get some new coils for the front, cut the fenders up and beat on it until it explodes.
 
cmelo said:
Plus axle tube diameter of the 8.8 you want to put in will add a little as well. I'm betting you could easily get away with an extended shackle if you didn't mind SUA. Relocate the shock mounts onto the axle, run the shocks that are on it and get some new coils for the front, cut the fenders up and beat on it until it explodes.
Click to expand...

I'll look into shackles. good call
 
With the regular stock 4x4 springs SOA on an 8.8 I've got a slight rake with RE 5.5 coils + 2" spacers - the stock spacer + winch, so about 6." lift to match. You should end up about 7".

I have an extra good pair of regular 4x4 leafs...want to trade? :eyes:
 
Mine is a metric ton and before the 2" AAL with my 14 bolt axle it sat at about 9". I'd have to say with a stock axle 7" is a safe bet.

THe last MJ I did SOA on with non metric ton springs it netted just at 6" of lift.

Everyone is pretty much spot on.
 
7.5 to 8" of lift.
 
alright. I'm going to set this in stone, because I have done it. these specs all with D44 axle (factory), and stock shackles, with a 1.75" tall spring perch.

2wd leaf packs = 5.75" lift
4wd leaf packs = 6.75"-7.25" lift (depending on wear)
M/T leaf packs = 7.5"-8.5" (depending on wear)

take off the difference for whatever perches you're using. any way you go about it, that's about the best reference chart you're going to get.



where people get screwed up is when they don't take into account the height (above axle) of spring perches, the axle tube radius of the axle they are using, and what shackles they are running. While leaf springs will obviously wear at a different rate varying truck to truck, these are generally as close as you will get.
 
foress_89 said:
I can't understand why no one agrees on how much lift?? 4.5 inch or 8?? the axle is roughly 3-4 inch why would it give 8 inch of lift?
Click to expand...


above and beyond you're misconception, outlined in my previous post....you've forgotten several things.


SOA lift comprises of the
A) height of radius of axle (NOT diameter, as the center point of the axle is the center of the shaft thus center of wheel)
B) spring perch height (the amount from the center of the arch to the surface which meets the bottom of the leaf spring pack)
C) thickness of leaf spring pack.

when SUA, the entire thickness of the leaf pack is below the axle. flop the axle to the other side, it's above the axle.


so, say your spring pack is 2.75" thick. and you're axle tube diameter is 3.5". take the radius of the diameter of the axle tube, plus thickness of pack, you have 1.75"+2.75"=4.5".

and that's without adding the fact that you've got at least 3/4" for the spring perch height....likely more like 1" to 1.5".


it's simple math. a typical 1" tall spring perch with those imaginary specs will net you a total lift gain of 5.5" of lift.
 
Here is an SOA with 4X4 springs and stock front
rd350006.jpg


Here's how it sat with 3" and 2" spacers up front
rd350007.jpg


Here's how it sits with 6.5" coils up front
2011-05-14101314.jpg
 
Last edited:
My SOA with 4x4 leafs (good condition) and a D44 gave 5 to 5.5" of lift.

Don't forget that MJ leafs are fairly soft ... it doesn't take too much weight to sag them down.

Here is a pic of my truck with the SOA described above and 4.5" Clayton springs and a .5" spacer up front. With a full size spare and a tool box in the back, it sits level. On 33s in the pic.

IMG_2484.JPG
 
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