My front coil over project is nearly complete. Now I'm thinking about how to get the rear end to flex equally as well. I would like to work with the existing leaf spring setup rather than doing coil overs all the way around.

So what are the pros and cons of a 3/4 elliptic rear suspension? On the surface it seems like an easy way to get more flex that seems more controllable than say a revolver shackle.

why aren't you just doing coil-overs on all 4 corners rick?

Some would say that a con is that on hill climbs you can get loss of traction. People experienced this with the chevy double shackle setup also. I think even with a traction bar you still might run into problems with bouncing and such on loose hill climbs.

If done correctly ( which it never is for some reason) you must use a 4-link and a dual shackle, That will eliminate the problems listed above. No real pros or cons to list, But if you do it right with a link system and dual shackles you don't need the goofy leaf, and just by freeing up the motion of the spring you will gain reasonable travel and a better ride.

To clear this up before it becomes a problem: Dual shackle is refering to a shackle at each end of the spring (not two shackles hacked together)

ericfilar@fatcity

I'm sure that Eric knows what he is talking about also!! :D

Got any pics? Technically it's not 3/4 elliptic if you are using a shackle at both ends of the spring then right?

I was going to use some leftover springs I have and do a 3/4 in the rear. I am planning a triangulated 4 link like Camo has. I just want to get more travel out of the rear for now until I get coilovers. So should I stick with the 3/4 or do the double shackle deal?

Ty Ty and Eric (Fatcity) are right. I ran a dual shackle (front and rear of spring) with a long 3/4 spring in the rear of my full-width YJ for a few years. Recently I ditched the 3/4 spring and rotated my shocks up (to get them more inline with the travel of the axle) and I am extremely pleased with the results. I lost a little travel (not even needed/practical for the trail) and can't say the loss is noticeable. I run trails in Tellico and Gardendale (Southeast U.S.) and had the oppurtunity to test the new setup out a couple weekends ago at the Superlift ride in Gardendale. I am now able to climb steep rocky grades with limited bounce resulting in more traction. My website has pictures of my old setup and I will try to post some pics of the new setup from the Superlift/Gardendale ride. Don't worry about the 3/4 spring and go with the 4-link/dual shackle setup. It performs similar to a coil-over setup and is a good bit cheaper. You'll love the travel and control.

Grumble.... thanks for all the info. I was trying to avoid moving my gas tank... I wasn't thinking links with a 3/4 elliptic.

My fuel tank is mounted inboard of the frame rails on the drivers side getting in the way of any link type setup. So I guess my first step is to get a BII fuel tank and mount it behind the axle freeing some room up under the truck.

My tank is in the same place. :( I just got a fuel cell. At least I can put mine in the bed.

Originally posted by Explorer
My fuel tank is mounted inboard of the frame rails on the drivers side getting in the way of any link type setup. So I guess my first step is to get a BII fuel tank and mount it behind the axle freeing some room up under the truck.

Originally posted by MattS


Technically it's not 3/4 elliptic if you are using a shackle at both ends of the spring then right?



A regular leaf spring set-up with or without a shackle at both ends of the spring is considered a 1/2 elliptic suspension

The only thing that makes it 3/4 elliptic is the goofy leaf, it has nothing to do with the shackles.

I've run this set-up on my jeep for over 7 years now and could not be more pleased with it.

ericfilar@fatcity

What would be the advantage to using a leaf spring vs. a coil in that case, since the leaf is no longer need to locate the axle?

None. The only reason I am doing it is because coils are big $$$ and I don't want to spend it right now. But for $30 I can make the rear flex until I can get the coilovers. I will have the 4 link done and all I will need to do is hack off the springs and build a mount for the coilovers and it's done.

Originally posted by LAME
What would be the advantage to using a leaf spring vs. a coil in that case, since the leaf is no longer need to locate the axle?

Originally posted by LAME
What would be the advantage to using a leaf spring vs. a coil in that case, since the leaf is no longer need to locate the axle?


No advantage, just helps keep you're walet from floating away.
ericfilar@fatcity

Originally posted by FatCity



No advantage, just helps keep you're walet from floating away.
ericfilar@fatcity

Thanks..just what I thought:D

Ok I read this post and was like hmm never heard of 3/4 elliptic so I did a little 0.47 search at google and found a lot about it but when looking at the pics and reading I wasnt sure if you need to do it to both sides or just on(kind of like a wristed arm). I think you need both sides just to get good flex on both sides, but then that brinks in the links system that yall where talking about so I think I am some what on the right line. Am I?
Justin<><

Originally posted by Explorer
I would like to work with the existing leaf spring setup rather than doing coil overs all the way around.


WHY ?!?!

is it a money thing?

otherwise, cant see a reason for doing it:eek:

Rick, while you might not be able to do a 4 link because of the gas tank, I believe that you can still run a three link. This is what I had planned eventually, with either coilovers or 1/4 elliptic. I'm not sure about the difference in the travel department between 3 link/4 link/ 1/4 elliptic/ and 3/4 elliptic, maybe someone can enlighten me. I imagine that a 3 link would a have a little more bind in it than a 4 link, but I doun't know how much difference it would make in useable travel.

Originally posted by Explorer
Grumble.... thanks for all the info. I was trying to avoid moving my gas tank... I wasn't thinking links with a 3/4 elliptic.

My fuel tank is mounted inboard of the frame rails on the drivers side getting in the way of any link type setup. So I guess my first step is to get a BII fuel tank and mount it behind the axle freeing some room up under the truck.

How 'bout Buggy-Bars? Anyoe have any pics? We're gonna build a set for a toy this weekend and would like to see sum pics. Can't imagine that we would need to link up the rear end for 3/4 Elliptic with bars. Maybe a traction bar....

Originally posted by Rock Toy
How 'bout Buggy-Bars? Anyoe have any pics? We're gonna build a set for a toy this weekend and would like to see sum pics. Can't imagine that we would need to link up the rear end for 3/4 Elliptic with bars. Maybe a traction bar....

Can you tell me the difference between a goofy leaf and a goofy bar?.

ericfilar@fatcity

Originally posted by FatCity
If done correctly ( which it never is for some reason) you must use a 4-link and a dual shackle,
ericfilar@fatcity

any advantages between the 3/4 with shackles on both ends of the springs vs a 1/4 elliptical ? since you had to have a 4 link to locate the axle anyway.

- jack

Well the 4 link is all thre work really. Once you have a 4 link done, you can swap juat about anything you want it. You can thrown some coils in there, some 1/4 elllip setuyp, coilovers, dual shackles, ANYTHING. If I was going for the 4 link, and invested all that tiem into it, I would swap in a 1/4 ellip setup. IU mnean you are most of the way there. I can see the dual shackle on the front, but I really hate things hanong off the rear on my rig. Ilike the negative departure angle. I have seen WAY too many rigs get stuck on their rear shackles. Just my .02

Dimitri

Originally posted by Rock Toy
How 'bout Buggy-Bars? Anyoe have any pics? We're gonna build a set for a toy this weekend and would like to see sum pics. Can't imagine that we would need to link up the rear end for 3/4 Elliptic with bars. Maybe a traction bar....

If you are describing what I think you are, I am running this-I don't trust a cut piece of spring in the 3rd quarter section. I run tubular arms with bump stops. It's simple and strong. I have been running this for years. You can pin them in thier static position, this alleviates the only downfall of this design(when climbing ledges/bouncing). If you build it this way with long springs on the rear, you have the best of both worlds without spending $$$ ...And yes, I run a traction bar. Sorry, I am unable to post pics here....:(
:smokin:

everything i know about suspensions and trucks tells me the one and only drawback to 1/4 elip. rears is street performance, and thats mostly in high speed maneuvers and braking which all stems from softness and lack of friction.(in our type suspensions)
the same thing you get with coilovers. or any soft long travel suspension.
my pig is what i like to call a trail rig, meaning that i do a little bit of everything from slow crawling to faster extended dirt road travel. i have found that all the "buggy" type mods are a hindrance in performance with me. great for slow driving but allowing too much soft uncontrolled movement for faster driving. not to mention the inherant "slop" in all the extra pivots. bouncing, sway, and a general looseness of the rear end is all pronounced with speed.
i find that a well balanced medium travel suspension is perfect for what i do, and i think it would be the same no matter what spring type i was useing. i just happen to use leaves for they're all around toughness and simplicity.
i think the more "exotic" suspensions are great for there intended target, from indy cars to trophy trucks, but they are all designed for that particular terrain which is why they work. build it, but build it right for what you are realistically doing. ok ok enough rambling, go build it man

3/4 eliptical:

pros. make you look good on a ramp :D

cons. make your rig uncapaple of climping big obstacales on the trail due to wheel hop.

of course i have never done a buggy leaf but have seen many fail to climb obstacles that otherwise the same kind of rig with out buggys made up no problem.

Originally posted by camo
3/4 eliptical:

pros. make you look good on a ramp :D

cons. make your rig uncapaple of climping big obstacales on the trail due to wheel hop.

of course i have never done a buggy leaf but have seen many fail to climb obstacles that otherwise the same kind of rig with out buggys made up no problem.

Not to sound like a broken record,
IF done correctly, with a 4-link and dual shackle it will work great.
A common mistake made buy the guy's who want to look good on the ramp, is useing a goofy leaf that is to long. Don't make the goofy more than 10" long and it will ellininate the above problems.

Now that said,
it is then, not worth useing the goofy leaf since you are only gaining maybe 4-6" of articulated travel.
ericfilar@fatcity

Originally posted by FatCity


A regular leaf spring set-up with or without a shackle at both ends of the spring is considered a 1/2 elliptic suspension

The only thing that makes it 3/4 elliptic is the goofy leaf, it has nothing to do with the shackles.

I've run this set-up on my jeep for over 7 years now and could not be more pleased with it.

ericfilar@fatcity


LIAR LIAR Pants on fire.......

You haven't used blackie ( for more than ten minutes ) in two years.But when it works it works awesome ( Driver is a big homo though ):flipoff2:

SO what is the benefit of a dual shackle over a 1/4 ellip or a coil setup? I mean I like the idea, and would not mind using that, but with all thw ork, I would throw in a few bucks more and a few more hours of work and do the 1/4 or coils. As for driving on the street, I loved driving my Flatty on the street. the 1/4 ellip kicked ass, It drove SUPER smooth, and cornered like a charm. I would even say it droive better on the street this way than it did with the leaves under it.

Dimtiri

Originally posted by FatCity


Not to sound like a broken record,
IF done correctly, with a 4-link and dual shackle it will work great.


i guess i have never seen one done correctly then because based on the performance that i have whitnessed i would never personally build one of these buggy leaf setups.

Camo, are you and Eric talking about the same thing? If so, why not do the dual shackle? I have seent ehm work great. AS for the buggy bar, it is great for droop,. but that is about it. We just did noe on a buddy's Toy. Came out really nice, but it is going to have that problem you were talking aobut when backing up. I gotta figure a way to stop that from happeniong. Some sort of a limiting strp./ I was trying to talk him into doing a 1/4 ellip on the back of his Toy, but he wanted to go with full leaves. Oh well, Good luck ot him.

Dimitri

flatty i'm sure it did drive nice on the street, a four link locates an axle well, but i was refering to the long and soft suspensions we run in general, i'm sure it didnt handle like the four link set-up on a nascar racer ehh?? requires a different kind of driving thats all.
on the double shackles, it flexes better(double in theory) over one shackle, and its kinda nice if you dont wanna mess with a panhard locater in the final link set-up. some like it because the axle follows a more up and down movement rather than the arc a normal single shackle leaf does. but that all depends on the links.

almost forgot, fatcity is right, a four link will not bounce any more than the tires let it if done correctly, i beleive the term is rising rate suspension, and i think camo is stuck on the buggy thing, which bounces like a lo rider and nothing i know of will stop it.

What if one were to do a 3/4E setup and use say a u-bolt (or something better that's just a quick fix) to pin up the buggy leaf right behind the rear shackle for driving on the street / steep hill climbs. Then when you wanted more rear flex on flat ground or wanted to look good on a ramp (heaven forbid :D) you could un pin the buggy and go to town. Good idea / bad idea?

Actually Rhino, the kind of suspension you have does not dictate the way the axle moves (in an elliptical pattern). This is all in the design of the 4 linbk. That allows the axle to move all over the place and "walk" under the rig. AS for the Nascar thing, find any truck that will drive even close to that. I mean we build for one reason really, and an addade bonus is if we can get the flex we want without comprimising the off roadability of the vehicle.

Dimitri

Originally posted by Flatty
SO what is the benefit of a dual shackle over a 1/4 ellip or a coil setup? .
Dimtiri

There's no benefit to the dual shackle over either one, I've never been a fan of 1/4 do to it's off-road antics. By antics I mean no disrespect, but in order to tune the suspension front to rear for rockcrawling it allways needs a realy soft front suspension, I like jumpin dunes and such.

To clarify what I'm saying:
A 1/4 elliptic rockcrawler always has more travel being used in the rear and hardly uses the front.
Example:
put a 1/4 elliptic rear rockcrawler on an rti ramp and in most cases you'll notice that the front has almost no compression takeing place.

Again I'm not looking for an argument, but if I'm wrong, please post a pic of it at ride height, on the ramp, and comeing in for a landing

ericfilar@fatcity

Originally posted by Brawler



LIAR LIAR Pants on fire.......

You haven't used blackie ( for more than ten minutes ) in two years.But when it works it works awesome

But it's ugly, I wan't a nice clean rig like the rest of you jackasses :crybaby2: ....shoemaker never has shoes....


[i]( Driver is a big homo though ):flipoff2: [/B]

Please don't make fun of my alternative lifestyle, or I'll send my life partner after you...He takes care of my lite work
:flipoff2:

Eric, you saw a great example of one downa t the hammers when my bro was there in his CJ7. It was a blue onw with a 460 in it, 1/4 ellip rear, SOA front, auto, 38's,... The thing is 60 40 with 60% being used in the front. I gotta say it is nice having the front work so well. The best part is he can drive the truck on the street, and even pull doughnuts in the middle of his parking lot at home (PAVEMENT)!!!!

Dimtiri

Originally posted by Flatty
Eric, you saw a great example of one downa t the hammers when my bro was there in his CJ7. It was a blue onw with a 460 in it, 1/4 ellip rear, SOA front, auto, 38's,... The thing is 60 40 with 60% being used in the front. I gotta say it is nice having the front work so well. The best part is he can drive the truck on the street, and even pull doughnuts in the middle of his parking lot at home (PAVEMENT)!!!!

Dimtiri

60/40's awsome, but is it stiff enough to jump? I know they drive good, anyone that say's different, built it wrong
I don't remember the vehicle though.
ericfilar@fatcity

He was hitting the dunes and jumping a little. I mean it was not a 6 foot launch, but he did "jump" it. In reality his is the only one I know that is built this way and with this kind of flex. If you want to build it SOFT, it will be that way. If you want to build it controlled, it will end up this way. I will try to get my bro to post a pic.

Dimitri

On level ground:

http://www.sierrarockcrawlers.com/community/rocktoy/Jv-Sergei

http://www.sierrarockcrawlers.com/community/rocktoy/DSC00005.JPG

Flexed up:

http://www.sierrarockcrawlers.com/community/rocktoy/Flex%20Shot.jpg

Nice pics!!

Do you have any with the front end on a rock as apposed to the rear?

ericfilar@fatcity

Here one of the front end on a rock.....doesn't show the rear flexing well at all.This was before we redid the rear a little:

http://www.sierrarockcrawlers.com/community/rocktoy/Rubiconflex

It looks like a realy well balenced susp. I remember the Jeep now w/o the lights
ericfilar@fatcity

Originally posted by RHINO

on the double shackles, it flexes better(double in theory) over one shackle, and its kinda nice if you dont wanna mess with a panhard locater in the final link set-up. some like it because the axle follows a more up and down movement rather than the arc a normal single shackle leaf does. but that all depends on the links.


Are you saying that a double shackled leaf spring will still locate the axle laterally? If so, that may be your solution Rick. Run double shackled springs under the frame and run links outside the frame. Nothing to interfere with your fuel tank and all the benefits of a link type suspension. What do you guys think?

Actually the double shackle setup will not locate your axle. yous till ahve to run a 4 link in there.

'Dimtiri

I know it won't do anything for fore and aft, but does it locate it side to side?

Originally posted by Grandpa Jeep
I know it won't do anything for fore and aft, but does it locate it side to side?

It will work with a 3-link (2-lowers & 1 streight upper )
But, I would'nt recomend it for driveing at speed.
ericfilar@fatcity

Why waste your time with a double shackle and a three link? You are one link away from a full four :flipoff2: Pony up some cash, get a pair of coil overs and call it good.

Well, I started a good discussion here and I've been sitting back digesting all the info. I appreciate the input.

What I have decided is that it's just best to get it done right the first time and not screw around. So, time to save the pennies and go for coil overs in the rear too.

Since I am no fab guru, I have to farm it out to a shop so it will take some time. In fact my rig is still sitting in the shop today waiting for the front coil over projct to be wrapped up. Everything is complete, just waiting for UPS to drop off the right coil springs.

yes a double shackle leaf spring WILL locate your axle side to side, all you NEED is two links going to the centerline of the axle on each side. your only controlling fore/aft movement. however i would want at least a 3 link for torque control as well.

ya know explorer, you have gotten alot of feedback here, and i think you have come to the right decision, just go a four link and decide on the springs, coils?? why not, theyre lighter.