Ok, I have a beer, and lots of free time. . .so here's what I'm pondering. I just got me some L&L ladder bars (used of course) and was thinking how it would work to put a shackle on the front of the spring as well, and use the ladder bar to locate the axle under the truck. This in theory (makes me sound smart, eh?) should let the axle move forward in the arc of the ladder bar unhindered, and yeild better flex than stock or even shackle flipped, and more lift

Any forseable problems?
Will the 3/4" heims be enough to locate the axle?
Should I quite my job to persue a carreer in art?

How best might the ladder bars be attached to the axle? Its supposed to be "U" bolted on, but I was thinking of something like the drag car bars that have a plate welded to the axle, and fix poly bushings to the LB's and bolt them on. Sould provide some give and more "twisty flex" (real technical term there).

Heres an illustration. . .

 

The idea looks good and so does the drawing. But I believe without a static mounting point on one end of the springs, axle wrap may be present.

I believe the system looks a little to dynamic and may hop up and down and possibly side to side.

 

It's a good idea. I have seen it used on a couple trucks that I've seen in pictures on the net and in magazines (since I'm a poser and never get out to see "real" built trucks...and it's not like we have any in MT anyway).

The problems I forsee are:

1. Sway. With shackles and bushings on both ends of the leaf springs, the axle will be more easily permitted to work itself sideways than if one side is mounted to a hanger.

2. L&L ladder bars are not beefy enough to actually locate an axle....especially on a trail rig or high-torque situation. They're also not going to allow articulation without turning themselves into pretzels.

The ones I have seen on trucks are used with a 4 link or 5 link system. That way, the pinion angle doesn't change drastically when the suspension cycles. Also, it's stronger in that the rotational forces of the axle are translated into a tension motion (push on one link-pull on the other) that is easily managed, whereas a ladder bar setup requires the pivot point to not only take the push-pull by itself, but also the up and down force the axle housing creates under torque.

Hope that makes sense.

Good drawing by the way!!!! Kudos.

Cody

Edit: Pic added.....

 

If you're gonna go that far why not ditch the leaf spring, swap in coils and a trac bar and have something that'll really flex? I don't see much an advantage do doing this with the ladder bars as the forward/backward movement of the axle is still going to be limited by the ladder bars and there for not going to give you any more flex of the shackles. Cody had some really good points about the stability of it too.

 

Becuase thats outside the bounds of the K.I.S.S. principle, at least for me Literally, all I would have to do was scrounge another pair of shackles from the junkyard for this.

But thats kinda the point? When you add the LB's you change the axles tendancy to rotate about the spring. . .to that of the LB's. When the suspension cycles, the front portion of the LS is being compressed or extended (or trying to be becuase its fixxed), by adding the shackle the the LS's are allowed to rotate freely in the suspension arc. Thats what I was thinking, did I just missunderstand you? Or am I confused myself

Very good points Cody, and yes that makes a lot of sense. I didn't take into account the extra rotational forces from unegual wheel travel. Just out of curiosity, how "beefy" would/should something like this be? And what is that suspension called? I did a google search and a search here and didn't find any relavent hits. On the subject of searches, what is the shackle setup on the front of the LB called? Of course, searching "shackle on ladder bar" turns up hundreds of irrelavent hits with any of the above search terms

Thanks again!

 

I just don't think you'll get near the spring compression it would take to flex both shackles to the point where you'll notice a big difference, unless you have a SOFT spring with a lot of arch to it. Most springs sit relatively flat already and they're not going to move a single shackle much when compressed, let along 2 shackles. But if you had a heavy duty enough set of ladder bars that would be up to the task of locating the rear axle you could do some junkyard coil springs and buckets, an a track bar and you'd have a pretty crazy flexing setup for cheap. I'm kicking this idea around for my rear steer next year. The big thing though, no matter which design you want to go with, is to buy heims that are STRONG or you'll loose that axle. Personally the only joints I would use for the job would be Twister's joints by Evolution. They'll run you about $55 each but they'll hold up to the beating.

 

you will not get much flex with ladder bars, I run them with the coils so they do locate my axle (no they aren't L&L stuff too light for my taste) and when I pull into the yard off the street it usually lifts one tire off the ground, and that isn't what I would call serious rockcrawling angles infact my wifes stock 89 bronco can make the same angle without lifiting a tire so if your going for articulation stay away from the ladder bars.

 

Good on 'ya for thinking outside of the box, but all the problems the gang pointed out with this plan are dead on. I have to say, I was shocked how feeble the L&L bars where when I first saw them, especially for what they sell them for.

 

Rob, do you use heims on all your ladder bar ends?

 

No just the front conection point no real point in using them on the rear except for adjustability on the angle but they won't move anyway so why put in another failure point.

 

Just a thought here but don't you think that a heim joint, on both connecting points at the axle and on the forward end of the ladder bar where it meets the frame, would increase articulation drastically with a setup like this? If you don't have any way for the axle to twist and no sideways movement allowed for in the joint it's not going to flex at all which, I imagine, is why you pick up a tire pulling into the driveway. I'm having a hard time explaining it but does this make any sense? I've only seen 1 truck with the ladder bar/trac bar setup in action but it flexed like mad and used 6 heims on the ladder bars plus 2 more on the trac bar. I don't see it any different than trying to make a 4 link without heims. If the links can only move in 1 plane of motion your suspension will only travel in that plane. If the links can move freely in any direction you should have great articulation too.

 

lets see if I can explain this so it makes sense but you have a solid mount on the axle so it's not going to move then the 2 bars in the ladder bar are welded at the front and have braces running down the length so they aren't going to move so in order for the heim joints to make any difference by moving one of the bars would have to have some type of slider to allow it to stretch which would also have the affect of eliminating the advantage of the ladder bar in the first place.
Did that make any sense?
edit BTW a shackle mounting on the front pivot point like used with a leaf spring ladder bar setup will allow for a lot more flex but can't be use to locate the axle in a coil or coilover suspension setup.

 

Well yes and no, I kind of understand what you're saying but I'm not following you on the slider portion. Think about a standard triangular ladder bar, 2 mounting points at the axle and 1 up front at the frame. Now if you have a standard hinge style joint at the frame (or at all 3 points) you can move the axle up and down but side to side movement is going to be almost zero, as well as any twisting movement. Now replace this with heims at 3 points (6 points total, 2 at the axle and 1 at the frame for each bar). Now if you had the frame on stands and a back strong enough to move the axle around you could move it side to side until the heims maxed out. You could twist it (by twist I'm talking articulation twist, one side up the other side down) drastically too, because there's no binding in the joints.

EDIT: Rob, I browsed your gallery again and don't know if this is where we're mixed up but what I'm talking about here is brackets welded to the axle and the ladder bar having seperate ends which can attach to the bracket with heims. In your case you're using a solid mount on your axle which doesn't allow it to articulate very well because there's nowhere for it to twist. We're running 2 very different kinds of ladder bars and yours are more similar in design to the L&L bars. What I'm trying to describe is actually far more like a 4 link (non-triangulated so I guess really a 5 link) except it only uses 1 forward mounting point at the frame. The advantage to this is you have more ground clearance because you don't have the lower links hanging so low. Here's my ladder bar at the axle:

 

I think what you are saying is that if you used heims on the ends of the ladder bars (as with a link suspension) along with the dual shackles on the leaf springs it would allow the suspension to cycle, unlike a rigid or fixed ladder bar. If you changed that then that aspect of the design would work as desired. Add another link to control sway, and this design would work, its just at that point just do a real four link as it would be better in every aspect and less complicated.

 

Ivan I understand what your saying but take some paint and paint your ***** in the heim joints (something like fingernail polish or plowcoat would work best) then take it out, and see how much gets worn off my guess is you will find that the rear hiem joints don't actually move at all. if you getting flex it's from the tubes twisting not the joints moving.
As I recall I believe your ladders bars have a slip joint in them this allows them to lengthen, and shorten with the leaf springs which you can't do with a coil sprung suspension and this allows for a lot more movement within the ladderbar plus allows it to "twist" with the articulation but with coils I don't have that option since it locates my axles front to back.