3/4 elliptical options w/SOA

[The Donzi]

Anyone have any experience/advice with using a 3/4 elliptical set up along with shackle reversal on front SOA?? I have used this set up on a short wheel base jeep and got good articulation without noticing too much difference in the ride quality. Wondering if my 79' Cherokee will tolerate the change as well?

How about a double shackle set up ?? Extra droop, extra compression just use a set of arms to locate the axle?

Any thoughts??
Jeff

[Stuka]

I am thinking you mean 1/4 elliptical springs? There has been recent discussion about usng these on full sized rigs. It should work really well. As for the double shackle idea with them, I am not sure how safe that would be on a heavier vehicle like a FSJ.

[The Donzi]

I think maybe the 1/4 elliptical name is a misnomer. If it is only a 1/4 of an ellipse it wouldn't hold anything up..... I just mean't the addition of another short spring attached to the frame with a shackle attached to the other end. I will check the archive, any kits that you know of??
Jeff

[rockjeep44]

Actually, he's not talking about 1/4 ellip. That would require at least a 3 link or 4 link. Basically he's talking about running a 3/4 ellip setup in the rear with dual shackles which has been done with pretty good success. This setup basically looks stock but instead of mounting the rear of the rear spring to the shackle it's mounted to a shackle which is mounted to a piece of a leaf spring which rests against the frame until it droops then it pulls away. Donzi, I think this will work well but not unless you have a good link system because 3/4 ellip in the rear will axlewrap like HELL. There are kits for CJs and stuff out there but if I was you I would just build my own. It's really straight forward and there are some good writeups out there.
-Andrew

[Gwamp]

Nobody makes kits like that for the FSJ's. it is all home made stuff. It can and has been done, you just need to make it yourself.

[Bob Barry]

CJ's and YJ's are much easier to do a 3/4-elliptical on, because the springs are under the framerails. On our FSJ's, the springs are on the side of the framerails, so there's no easy mounting point unless you fab some brackets to bolt to the side of the frame.

There is, however, an idea rattling around in my mind for a wilder elliptical suspension setup. I haven't seen it anywhere, and it involves more flex than a 3/4-elliptical; maybe it should be called a 7/8-elliptical? Here's what I'm thinking:

This is the original SOA rear suspension setup-

http://home.off-road.com/~wagoneer/tech/fsj_rear_susp_stock.jpg

What I had in mind was utilizing an original rear spring pack, mounted in the front in the original location, but with the pack inverted, and with the center of the spring supported by a pivoting bar that was bolted to the underside of the framerail (which would need reinforcing).

The rear shackle mount would be cut off of the frame, and a new lower mount would be added for the front eye of ANOTHER spring-pack, which would be attached to the rear eye of the upper pack by an ordinary spring-shackle.

This is effectively an inverted shackle setup like Riverbeast's, but instead of a rear shackle mount fixed to the frame, the rear shackle mount would be an entire leaf spring. Here is a rough diagram:

http://home.off-road.com/~wagoneer/tech/fsj_rear_susp_7-8.jpg

This would have at least the flex of a 3/4-elliptical setup, and probably more, if the upper center spring pivot was allowed to creep forward and back a bit.

It would also need some major dampening, not only at the axle housing, but it would probably be a good idea to add a shock-absorber to the rear shackle itself.

This setup would also require a track-bar for any kind of lateral stability, unless there was a trac-link tied into the rear shackle. Such a link could be the full width of the frame, which would not limit the flex at all.

Another advantage would be the ability to use two spring-packs of half the original load-capacity, so each pack could be half as stiff as the original.

Yet another advantage would be the fact that you don't really need any frame beyond the upper center spring pivot. Plus, you could try out any length rear spring you like, as long as you have four of them. You could alter the wheelbase with different spring packs.

Like I said, this has been rolling around in my mind for some time, and I've never seen it put into practice, though I wouldn't doubt that it has. It would have the advantage of massive flex, a soft spring-rate, and relative simplicity. For on-road use, it would even be possible to pin the rear eye of the upper spring in place, which would provide the same geometry as an ordinary inverted-shackle rear suspension.

Tell me what you think.

[tomd]

If you want, i can draw up an idea i had a while back, just uses some braced angle iron bolted to the side of the frame. I never built it, so its not precise measurements, but should give an idea.

[Hump]

There you go dreaming up all that crazy kind of stuff again. Always gotta be using that brain of yours.

I think it would work, but you would definitely need limiting straps. It looks like the only thing that would stop it, as you have it, would be when the top spring is almost vertical and hits the bottom front mount. Could be a little tricky making a driveshaft with that much travel. Pinning the rear shackle sounds like a good idea for regular use, but you would have to do it so you still get the shackle motion or you would get a nasty stiff ride. Springs got to be able to go somewhere.

[Bob Barry]

Originally posted by Hump:
I think it would work, but you would definitely need limiting straps. It looks like the only thing that would stop it, as you have it, would be when the top spring is almost vertical and hits the bottom front mount.That upper center spring-pivot would be fixed to the frame, so that front half of the upper leaf would not be able to droop. That pivot would need to be able to move forward and back a bit as the spring flexed.

A long-travel driveshaft would be absolutely necessary.

[rockjeep44]

Basically what you've created here is a 3/4 elliptical setup with a standard size leaf spring rather than a chopped down version. I don't think the benefits of the setup would be much over that of a regular 3/4 setup. I see it having some really bad flex steer. Honestly, instead of crazy leaf spring setups just do a simple triangulated 4 link with some F150 coils and that would be all you needed without all the trouble.
-Andrew

[tuck]

Originally posted by rockjeep44:
Basically what you've created here is a 3/4 elliptical setup with a standard size leaf spring rather than a chopped down version. I don't think the benefits of the setup would be much over that of a regular 3/4 setup. I see it having some really bad flex steer. Honestly, instead of crazy leaf spring setups just do a simple triangulated 4 link with some F150 coils and that would be all you needed without all the trouble.
-Andrewdude, did you just say "simple triangulated and 4 link all in one sentence?" ... hehehe

I've got to wear out my leafs first, and then I think I'm going to follow the crowd to 4 links. Give me a year or so.

[rockjeep44]

lol, i hear ya but really they are quite simple. The jerks over at pirate act like it takes a phd to build one and if you don't know how you're an idiot. Basically I learned by spending countless hours just staring at different ones and asking questions. Nothing to it smile.gif
-Andrew

[The Donzi]

Thanks for input guys. Bob Barry thanks for the drawing! I like the idea of flipping the stock spring. I was thinking about a similar setup using a greasable slide mount as the center pin (6" of fore aft travel) I have seen these used on some CJ's as the spring mount instead of a shackle. If I used a slidable center pin I could then just make it a full elliptical set up....
I have never driven a full elliptical on/off road what are the adv/dis of this??

And Rockjeep44 how bout a little more about that 4-link coil setup sounds interesting..Any links for info?
Jeff

[Bob Barry]

Ah, Andrew; EVERYBODY'S doing 4-links these days... ;)

There are problems with lateral stability on a 7/8-elliptical, though probably not worse than a 3/4-elliptical would be. Well, here's a modified drawing, with ordinary shocks, a pair of kicker-shocks, and the lateral heim-joint track-bar mounted on the shackles to provide more lateral stability.

http://home.off-road.com/~wagoneer/tech/fsj_rear_susp_7-8_cut.jpg

[scotty]

did i misinterpret the original question? not that i mind the discussion of 7/8 elliptic rear, ;) but i thot he was askig about a 3/4 etup on the front axle?

only thing id say about running it with a shackle reversal is that youd hafta have one heckuva drivesahft to tolerate all that movement. :eek:

what about running it up front with a front mounted shackle?

[tomd]

Originally posted by scotty:
did i misinterpret the original question? not that i mind the discussion of 7/8 elliptic rear, ;) but i thot he was askig about a 3/4 etup on the front axle?

only thing id say about running it with a shackle reversal is that youd hafta have one heckuva drivesahft to tolerate all that movement. :eek:

what about running it up front with a front mounted shackle?Wow, boy was i not paying attention.

On the front, you want to be careful w/ a shackle reversal and 3/4 elliptical, for one because of the driveshaft travel issue, and, at least w/ revolvers, i have seen where people try to climb up a ledge, and once the front tires get on top, the revolvers just unload, i would think a 3/4 elliptical could be similar, haven't seen it, but seems like it might. I would do it in the front personally.

[The Donzi]

I was originally just curious about the front shackle reversal with a 3/4. I am in the process of completely redoing my suspersion setup and I wanted to try something radical. I am switching to SOA front and probably 3/4 elliptical front.

With a short leaf attached to the frame up front, will I need to set up a 4-link / trackbar to stabilize?

[scotty]

74 wag,that what i was kinda thinking with the unloading issue. it may work well to design something that would notlet the frame spring drop,so that you could lock it if you were going to climba nig gnarly hill that unloading may occur. pull a pin or something to unlock when you want to travel across a rock garden where max articulation would be needed.

im having trouble picturing a system that would be able to work to its full potential with a reversed shackle. since the front axle moves more,youd need one one heckuva slip yoke to let the axle droop to the full extent that the 3/4 elliptic would allow. id be willing to betthat youd need limiting straps no matter how long a travel shaft you had.it would be real toughto have a shaft that would not compress all the way,or pul apart at an "unlimited droop"

donzi,will you be driving this rig on the road at highway speeds? if so i think a trac bar may be a good idea. at slow trail speeds,id think you would prolly be ok without one.

hmmm. now ya got me thinkin ;) 3/4 elliptic front :D

[The Donzi]

I will be driving at highway speeds to get to the trails since I live in the right in the middle of of New orleans. Do you think that the 3/4 front w/o a shackle reversal will need to braced (removable pin etc..) at the frame to prevent unloading?
Ok, time for a stupid question, what happens during unloading of the front shackle(revolver)?

Also, would a tracbar be necessary on the trail also? for lateral stability???
Thanks for the input guys.
Jeff

[rockjeep44]

I think that instead of going to all the trouble of running 3/4 elliptic just slap a set of $150 revolvers in the front. You don't need a front traction system (3 or 4 link) you don't need a shackle reversal, you don't need a long travel driveshaft, and you don't need limiting straps. I run revolvers front and rear without any unloading problems that you always hear about. It's probably because these rigs are too heavy for that. And, I've wheeled my revolvers as hard or harder than anyone I know. Only problem I encountered was excessive axlewrap in the rear that I cured with a simple traction bar. Oh, and they work on the highway no prob. If you haven't seen how well this setup flexes then here is a pic. This is revolvers front and rear with a rear traction bar and Alcan springs SOA with rancho 9012 shocks.
-Andrew
http://www.fullsizejeeps.com/jeeps/files/1984-1992-GrandWagoneers/fsjflex1.jpg

In the name of fast page loading here are direct links to the other pics.
http://www.fullsizejeeps.com/jeeps/files/1984-1992-GrandWagoneers/fsjflex2.jpg
http://www.fullsizejeeps.com/jeeps/files/1984-1992-GrandWagoneers/fsjflex3.jpg
http://www.fullsizejeeps.com/jeeps/files/1984-1992-GrandWagoneers/fsjflex4.jpg
http://www.fullsizejeeps.com/jeeps/files/1984-1992-GrandWagoneers/fsjflex5.jpg

[Bryan]

I know nothing about 3/4 eliptical or SOA but I love your name, "The Donzi". Do you have one? I ran a Donzi 22 classic for years. Had 460 ford with a king cobra outdrive, through hull pipes. Loved that boat & will get another one soon. Oh yeah sorry this has nothing to do with your topic tongue.gif

[rockjeep44]

Donzi, basically since coils have no stability whatsoever they require either a 3-link with a tracbar or a 4-link (better). BTW, there is a difference in tracbars and traction bars. I run a traction bar in the rear. A tracbar is that stupid bar you see on most jeeps that runs from one end of the axle up to the frame on the other side. Yea, they suck. Anyways, if you want max articulation you're going to want a triangulated 4-link (in my opinion). Don't let the name scare you. It is quite simple. It would take a long *** time for me to explain it when you would understand much more quickly with a picture and then ask questions from there. So, my advice would be to search Pirate4x4.com and other sites on the net and pull up some good pictures then come back to this thread and toss your questions into the mix. Here are two very crude drawings I did. These are basically the two most standard (read: works well) ways to triangulate a rear suspension. We could talk about other wacky ways till we're blue in the face but these are tested and proven. Good luck
-Andrew
http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/4-link1.jpg
http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/4-link2.jpg

[ February 13, 2003, 09:24 AM: Message edited by: rockjeep44 ]

[dnixon]

here is a link regarding 1/4 elliptical and the link set up.. seems to be a pretty good set up..

http://www.pirate4x4.com/forum/showthread.php?s=&threadid=113924&highlight=triangulated (http://www.pirate4x4.com/forum/showthread.php?s=&threadid=113924&highlight=triangulated)

here is kind of neat one that is different for coils
http://www.pirate4x4.com/forum/showthread.php?s=&threadid=90878&highlight=triangulated

[ February 13, 2003, 12:03 PM: Message edited by: SLOwag aka-dnixon ]

[FSJeeper]

I have looked at all kinds of setups and almost went with the 4 link/coil setup which would have cost about $4000 to do it right.

After seeing RockJeep44's setup posted here last summer, I decided his FSJ flexes as much or more than I will ever need. I think he has developed the most practicle, cost effective, and useful setup a fsj needs. It is no secret I am copying him. All I need to do is get my ride height decided on, (I have too much lift with the M715 rear tubs and front fenders) and I am ordering Alcans.

[blt2krl]

Yeah right FSJEEPER, we all know your opinion on revolvers. tongue.gif I second the setup Andrew is running is the most practical and cost effective. I do like to see these kind of posts though. You guys have some great ideas.

[FSJeeper]

BLT2KRL,

Never one to be controversial, I do admit I have been waiting to hear complaints from you guys actually running and having experience with your revolvers.

I have to admit, I am very encouraged with you revolver guy's experience with them and can't wait to try mine out.

LOL, I have changed my mind on the Choptop and am swapping to a 380 HP SBC stroker, T400, and doubler along with higher geared D60/D70 armored personel carrier axles with detroits. Also making my choptop removable and extending the top to accomodate a flat, foldable M715 windshield. RockJeep44 looks like he is having to much fun with his open top and I want that option too!

Anyway, it will be a month or so before I get to actually try out the revolvers.

[The Donzi]

Rockjeep44 it took me a while to digest all of those posts but I think I understand what you mean about triangulating the rear. Is you triangulation achieved throught he shock positions? Because I couldn't see any locating arms? So, all I would need is some high articulating springs and new shocks locations that allow for lateral sability in either of the configurations you drew up. That sounds like a really trick and simple design. I will search some other databases to find some examples.

Do you have a similar set up up front? I don't see any kind of trac bar or opposing shock congifuration. Do you need to triangulate the front?
Thanks for all the help guys!

Oh and I have been getting some posts about the name Donzi. I will post a pic under Gen Disc later that explains.
Jeff

[dnixon]

Originally posted by The Donzi:
Rockjeep44 it took me a while to digest all of those posts but I think I understand what you mean about triangulating the rear. Is you triangulation achieved throught he shock positions? Because I couldn't see any locating arms? So, all I would need is some high articulating springs and new shocks locations that allow for lateral sability in either of the configurations you drew up. That sounds like a really trick and simple design. I will search some other databases to find some examples.

Do you have a similar set up up front? I don't see any kind of trac bar or opposing shock congifuration. Do you need to triangulate the front?
Thanks for all the help guys!

Oh and I have been getting some posts about the name Donzi. I will post a pic under Gen Disc later that explains.
Jeffif you check my post there are some pictures that will show you exactly what he is talking about...

[The Donzi]

Thanks Slowag, I checked out the link and that is exactly what I was looking for. I'm going back to the drawing board , I will post with any questions later. Thanks again guys.
Jeff