A well tuned leaf spring setup or 4link rear.

[customcreationsllc]

I think the leafs in the rear would work, leafs give you a nice constant roll center and stuffing the mounting points up higher in the body will actually raise your RC (Leaf RC is the line between the frame mounts directly over the axle)

Leafs suck for axle stability, basically a spring holds your axle in place so the whole axle moves around where ever it gets pushed. Like hard corners the axle will shift to the side. Pan Hard would help.
When you hit something hard the axle will push backwards as the spring straightens out then springs forward.
Never mind axle wrap.

Leafs wouldn't be as bad in the rear as the front you need the stiff front for drops and steering, and approach angle is more important then deproach angle.

Having a Leaf sprung vehicle I watch those axle move where ever they want.
My next jeep is going to have all links what kind I have not figured that out yet.
They all have their trade offs.

RCrocs you should be able to build it for class 3 / WE-Rock Promodified.
I would check the rules so you can meet as many classes as possible.
RCrocs, WE-Rock, KOH, Rausch Creek Racing, Southwick Racing

Everyone that rain Air shocks said they faded by the end of the race.

Give me a couple years to save and I'll be building a go fast rock crawler too.
I'm just dreaming up Ideas right now.

[SupermanIce-J]

I just don't see the point in setting up your rig for real coils. If you are going to 4-link it, run coilovers or airshocks.
(airshocks would be cheaper)

I think if I did go the rear links route i would probably do CO's... Rock Krawler is coming making their own shocks now...Can get them discounted as well.

I think the leafs in the rear would work, leafs give you a nice constant roll center and stuffing the mounting points up higher in the body will actually raise your RC (Leaf RC is the line between the frame mounts directly over the axle).

I believe that RC means roll center... can you explain if raising your roll center is for the better or worse?? It sounds like it is worse but IDK.

Leafs suck for axle stability, basically a spring holds your axle in place so the whole axle moves around where ever it gets pushed. Like hard corners the axle will shift to the side. Pan Hard would help.
When you hit something hard the axle will push backwards as the spring straightens out then springs forward.
Never mind axle wrap.

Leafs wouldn't be as bad in the rear as the front you need the stiff front for drops and steering, and approach angle is more important then deproach angle.

Having a Leaf sprung vehicle I watch those axle move where ever they want.
My next jeep is going to have all links what kind I have not figured that out yet.
They all have their trade offs.



Everyone that rain Air shocks said they faded by the end of the race.

Give me a couple years to save and I'll be building a go fast rock crawler too.
I'm just dreaming up Ideas right now.

Thanks for your insight... very helpful.

Also thanks to everyone else for your help.

[customcreationsllc]

Ya RC = roll center.
Your body roll is based off the distance the Center of Gravity (CG) is over your roll center.

When you go around a corner the CG puts a force at the CG height straight out.
The the higher the CG is over the RC the more Moment (engineering work for torque) it puts on the body therefore the more body roll you have.

Some body roll is good. When you go around the corner weight is transferred to the outside tire for more traction the outside tires do all the driving in corners. But if you get too much roll you can overload your outside tires. So it becomes a balancing game.

Most Lifted trucks the CG is way way above the RC. So a Higher RC is better.

If the CG and RC were in the same plane you wouldn't get any body roll.
If the CG is lower than the RC it would roll inwards and you get what they call a jacking effect that wants to lift the outside tire really bad for driving.

Link suspensions (Use the 4 link Calculator to determine the RC) basically it is the center of the pan hard bar (3link) or where the 2 links cross on the axle(triangulated 4link). That's part of the reason most people have the links mount really high over the axle.

But the problem with Link suspension roll centers moves up and down with the axle, (all the link angles change)

That is why people say with links there is little warning when you roll as the axle drops the RC drops and you go over faster and faster.

Leaf springs the RC is determined by drawing a line from the leaf to frame bolt to the shackle to frame bolt then a vertical line from where the tire hits the ground.
You can see how leaf RC don't move so you get a very stable predictable Vehicle.
You can balance the jeep right on the point of rolling because the RC isn't moving.

Circle track race cars they actually move the RC to the opposite side of the car so the can make left turns better.
That is why they have adjustable pan hard bar mounts.
The Featherlite race cars I used to work on used Watts links (fancy pan hard) wherever the Watts link mounts on the Axle is the roll center it was shifted to the side and had an adjuster screw so you can change the RC height in the pits, it balances out under/over steer.

There is a lot that goes into link suspension. Not only RC but Anti squat, Roll/bump Steer, and everything changes as the body rolls etc.

That is why I went with a Leaf sprung jeep, very stable I just have the problem of wandering axles it is not as solid as links.
Only thing you need to worry about with Leaf springs is the leaf angle it changes your brake dive anti squat. That is why I don't like lifted shackles it changes those angles.
Then you have shackle angle which it kind of gives you a progressive spring rate.

Travel is also limited on the Leafs I would like to see someone get 20" of travel with leaf springs you would need some really long springs. (I'm not taking about articulation, full axle up and down)

Hope this starts you off in the right direction.

[XJLI]

You seem like you are contradicting yourself. You say if you were to run KOH there is no chance in hell you would run rear leaves. But you then mention if you were to build your rig for crawling and speed (KOH) you would utilize a nice link setup up front, and linked rear "if you wanted to". From my research I have heard a properly linked rear is much more important. I could be completely overlooking sarcasm here but that was just what i took from your post.

building a multipurpose XJ should not be confused with building a rig for KOH.

[SupermanIce-J]

Well I have spoken with Rock Krawler and have convinced myself on the rear conversion.

I have even unofficially convinced Rock Krawler to help me set the rig up for Coil-overs!!!

Now I just gotta get my ass in gear and start working on this peice.

[XJtheXtremeJeep]

my vote is to definitly just go with a linked setup in the rear, youll never have to worry about wrap etc jjust take your time setting it up with all the geometries

[grundlepunch]

Well I have spoken with Rock Krawler and have convinced myself on the rear conversion.

I have even unofficially convinced Rock Krawler to help me set the rig up for Coil-overs!!!

Now I just gotta get my ass in gear and start working on this peice.

going to cut a hole into the body? what are you going to mount the coil over to? whats that going to tie into?

any xj i have seen with coil overs/air shocks have an internal cage that the coil over mounting hoop is tied into.

im just mentioning this because going to this type of setup opens up an entire new can of worms for mods to your jeep

[SupermanIce-J]

There won't be a body... except lexan panels.

AS far as mounting I am not sure yet... possibly hoops tied into cage. Or use RK's tj Coil-over conversion brackets modified to tie into my cage.