3/4 Elliptic Tech Notes or Advice?

[Stahlgewitter]

I am redoing the rear suspension in my XJ and am very interested in a 3/4 elliptic setup as a low cost solution for maximum flex. I am familiar with the standard 3/4 elliptic setup using buggy springs and wouldnt even be bothering you all with this except I intend to use a full main leaf, shorter than the stock xj spring length. I plan to fabricate a second spring hanger behind the stock hanger to retain the other eye, reducing the twisting motion and strain on the center mount of the buggy spring (I know its not a true buggy spring since im using a full main leaf, but Im referring to the top spring as a buggy spring for ease of understanding).

My questions are these: First, what vehicle should I source this buggy spring from? It needs to be shorter than the stock xj spring and be able to flex enough to pull away from the frame.

Second, any input and ideas on capturing the center of the buggy leaf? Obviously its not as simple as making another spring plate and holding it together with u-bolts on our unibody vehicles. Any ideas other than cutting through the floor or welding bolts to the frame as WanderingWillys has done. Im not dismissing these solutions and I may use either one, Im just looking for more ideas.

Last, in everyones opinion is it more advantageous, strength and reliability wise, for me to go with a full main leaf instead of a standard buggy leaf?

Thanks in advance for any input and sorry for the long post.

 

[Capt. Nemo]

http://www.naxja.org/forum/showthread.php?t=81590&highlight=quarter+elliptical

 

[Lincoln]

Capt., he's talking 3/4 not 1/4. I haven't seen anyone do those in a very long time.

Stahlgewitter, I just question why?

Spring packs have come a long way since (kind of) since 3/4 was popular. Hell the folding shackles even came after them. I think you could get just as good of flex out of a set of tuned junk yard packs. Then you also wouldn't have to deal with the stability problems and spring wrap problems that are introduced with the buggy spring.

It's been a while since I ran leaves but I believe the MJ pack is longer which would also increase your travel.

Personally I would rather have balanced suspension that doesn't flex as much as a massive flex setup that is not balanced well.

 

[CRASH]

3/4 elliptical is really not an ideal solution to any problem. Max flex is very over-rated.

If I was to do one of these setups, however, I would cut an XJ main leaf down to 12 inches or less and use the large bushing end to mount my shackle. I would sleeve and plate the frame for 9/16" bolts, then drill my stub leaf.

 

[Goatman]

I don't understand the point of using a full length leaf for the buggy spring. I'm assuming you're meaning to lay the funny leaf against the frame? Doesn't the frame curve up over the axle? If you have something else in mind on how you'll mount that leaf please explain. If both of the spring hangers that locate the axle are in front of the housing, that looks to me to create some nasty stability and handling problems......maybe I'm not getting what you're talking about. There's no way any of us would know what application a shorter main leaf would come from, just go to the junkyard with a tape measure and start measuring leaves.

Most of us are WAY past making modifications just to get more flex. Flex is definitely overated. I worked to make mine flex more, and since I hit my maximum flex (about 6 years ago) I have been gradually taking the flex back out of it. It's so easy to get the amount of flex that's needed for good trail performance out of a standard suspension that there just isn't any need for alternate solutions unless a person just wants to play with ideas or be different......and gaining the absolute best possible trail performance is a secondary goal. Stability and handling should be equal (if not prefered) goals along with adequate flex.

 

[Stahlgewitter]

Here is a picture to help better illustrate what I was thinking with the full length 'goofy' leaf with two spring hangers. http://www.pirate4x4.com/tech/suspension/buggyleaf/fullspring3.jpg

And a picture of how WanderingWillys has done his 3/4 ellip setup. His is the only example I have been able to find of a buggy leaf setup on an XJ
http://home.off-road.com/~wanderingwillys/xjpics/Buggy_leaf/buggydown2.jpg

As for the questions 'Why?', Goatman has it right, I am mostly exploring this option for the sake of being different and playing with ideas that are outside the box.

As for funny handling characteristics, I would use a lockout pin just behind the shackle to keep the goofy leaf against the frame while on the road to keep it from unloading, making it essentially the same as a standard leaf suspension until the pin is removed.

What Im gathering is that everyone feels that I'd be better off running MJ springs or 63" Chevy springs? Keep the input and constructive criticism coming

 

[Goatman]

The first link didn't work. Also, I'm talking about handling and stability on the trail, though it also applies to the street. Sometimes I think people forget to consider that the leaf spring has to locate the axle AND transmit the power/momentum from the axle to the frame/body. The leaf spring is acting as a control arm. When you allow the spring/axle to be that free moving those forces don't get directed properly to the frame and you end up with lousy things happening on big climbs when rear traction is very important.

When you have two lockers, any rig will crawl rock gardens regardless of how much flex (the deciding factor there is ground clearance more than traction). So, what seperates one rig from another is how they climb, and all those funny springs and shackles don't climb as well because they don't direct the power to the frame as well. They also aren't fun on steep drop offs when the rear end kicks up needlessly.

 

[Gerr]

WOW now I have no idea what all this is about but this pic just doesnt look like it would be safe

http://home.off-road.com/~wanderingw...buggydown2.jpg

Im a noob when it comes to modified suspension. anyone care to point me to what in the hell it is and why

 

[Stahlgewitter]

Sorry for the invalid link. here is the page for the writeup. I was referencing the third picture on that page. http://www.pirate4x4.com/tech/suspension/buggyleaf/

And now that you mention it, I just noticed that this was written in 1999 it looks like. It seems you might be right about this concept being outdated, though there are recent posts on various Zuki and Toyota forums from people who are still utilizing this design and are very pleased with the results.

I also understand what you mean about inefficient transmittal of power/momentum while climbing.

Im still waiting to hear from someone who has used this setup and can give real world feedback on how it performs.

 

[Lincoln]

I haven't used it personally, but I did have several friends that tried it back in the late 90's.

Problems that were easier to get rid of than try an fix:
1. Unloading. No help from the axle on holding the body down. When corning all of the weight would want to shift at one. It would feel fine then all at once there was a bunch of body roll. The same affect happened on the trail.

2. Horribly axle wrap. With the goofy leaf the spring pack does very little to prevent it. Instead of the spring distorting the entire pack pulls down and stretches out the goofy leaf. The only thing I have seen worse were the revolver shackles.

3. Weird spring rates. Stiff packs kind of started the craze and it would go from almost a zero rate to a stiff rate in an inch or two. Similar to when a spring comes out of the seat except with a normal setup the rate would come in more gradually (again when higher rate packs were the norm).

To me they are no different than the folding shackles except the shackles have a hard stop when they top out. Even on those they started realizing that it should be limited to an inch or two of unloading to fight the unstableness (fawk I suck at English ). To gain an inch or two it really isn't worth it.

 

[tacobuggy101]

I hated my 3/4 elip. set up. It wheel hopped so bad it was scary like a foot or so. It also un loaded around curves (wasn't secured soild to the frame at the eyelet for street driving, should have been!!!!!!!!!!!!!) it felt un stable on the trail too. I wouldn't do it again

Later, Jake

 

[Stahlgewitter]

Hey Jake, Do you have any pictures of your setup still? If so I'd like to see them. Did you keep the springs outboarded like factory or relocate them below the frame? Do you remember what spring you used?

 

[tacobuggy101]

sorry i failed to mention this was on my tacoma. But i still think its a bad idea no matter what its on! I used a cj2a stock main leaf as the goofy w. a 6 inch shackle and stock springs (38.5 1100 boggers and cut fenders) dont get me wrong it flexed for days but it was def. the wrong way to get there. If i was you i would find some flexy leaf pack in a scrap yard and inboard them slightly im willing to bet that would give you the flex your looking for and no teeth shattering wheel hop. I run a hybrid 3 leaf pack in the rear of my truck w/ stock 56" taco springs main and 2nd w/ a full length arched spring from a custom leaf pack from competition spring co. I think it was a 12" rear pack for an f150 not for sure though. i run an 8 inch shackle and inboarded them 6inches per side. Im very pleased with it no wheel hop, real stable on and off road, flexy too. Btw thats with a d70 and 44's

Later, Jake

 

[Stahlgewitter]

Thanks for the input Jake. The more I learn about this the more I feel Im better off finding a different solution. I was never set on using a 3/4 elliptic, I was just thinking of ways to do something different. I think Im going to go with inboarding the leaves and running some longer MJ leaves with s-10 leaves mixed in. My current setup is stock XJ main with s-10 Blazer leaves so I'll just swap those over.