Traction Bar

I was looking at this link for a traction bar & it looks like it could work.
http://www.jeepaholics.com/tech/bambar/
I'm just wondering where i'd be able to attach the shackle end on the unibody? I'm thinking my Cross Shock hoop but i'm not sure if that tubing could take that kind of stress. Guy's need help here.

I have been contemplating a traction bar similar to this design, however I have one major concern. The vertical bar would work great at eliminating spring wrap, but what about the times when the rearend needs to drop equally at both ends. I can see that the bar would work during articulation, but I cannot see in my mind how the rearend would be allowed to sag equally at both wheels. I am talking mainly high speed driving, (think large pothole that both wheels would drop into at the same time. What effect would this have on the handling?).

What he seems to be doing is using a single bar to emulate the anti-wrap action of a 3-link suspension such as found in a ZJ. If I understood the description correctly, JJ13's question would be a non-issue because there are two joints in the assembly -- one above the diff/axle, and another forward where the link attaches to the chassis/body.

I'm having trouble really visualizing this thing in action. For all the photos, IMHO they suck because I still don't see just how it all goes together and works.

Where is MaXJohnson when we need him most?

Seems to me like this is the traditional design (with a link) stood on it's end in a vertical design. I can't see that it would exhibit anti squat characteristics any different. It has simply captured the rotational forces and they will manifest themselves in the only direction that the system allows: up/down, just the same. The lengnth of the horizontal link would provide bind in a both sides unloaded situation, but that's mostly a high speed thing. I do like the fact that this design is centered, but the clearance issue would be the big one for me. That and the trouble of welding to the pumpkin. I guess his design isn't welded that close to the pinnion bearing, but I can see buddy backyard welding 'pro' mess up a pig pretty quick. When I build my traction bar, I dont think it'll be this one.

At a glance, it appears as though the authors of the article don't realize that they have created a 3-link suspension. Their understanding of anti-squat seems to fall a little short as well.

The design of a normal leaf spring suspension is similar to the Ford radius arm design where you have an arm on each side rigidly connected to the axle and pivoting at the chassis. The equivalent link of a leaf spring is very short and consequently, leaf spring suspensions have a high amount of anti-squat(compared to link designs) Adding the "shackle" to a leaf design creates a third link.

The difference between this set up and a normal 3-link is that the leaf is rigidly mounted at the axle where as on a 3-link both upper and lower links pivot at the chassis and axle mounts. The lack of an articulated joint at the axle (spring pad) would bind up the suspension. This binding is alleviated by compliance in the leaf, but would not have the freedom of movement allowed by a normal 3-link design. Imagine adding a third link to a Ford radius arm suspension.

Since ths design is the equivelant of a 3-link, the length, angle and attachment points of this upper link (shackle) would have a major influence on the instance center. Contrary to the article, adding this link could have a major impact on anti-squat. Pinion angle gain would also be affected.

Knowing the effect this upper link would have on the suspension, you could experiment with different lengths and angles in an attempt at a reasonable design, but as already mentioned, the packaging would be a problem as well.

No wonder Richard G. and some of the other BOTW boys run the traditional ladder bar w/shackle.

I think I might go w/ Sam's Off Road Traction Bar w/ Johnny Joints at all ends. The concern is that this attaches it self to the axle tube where as the other one is on the pumkin. I'm wondering if the axle would twist out of the pumkin if enough force is put on it?

Pumkin mount is superior to axle tube mount, for the reason you stated as well as helping control the wrap up where it emanates from, the differential. Torque will have even less chance for damage at this point.

XJguy

Visit the MADXJ site. One of the guys there did a traction bar that I copied.

My version has poly bushings on the axles mount (axle tube as close to the pumpkin as I could) and a heim from a tractor toplink mounted to a shackle at the tcase skid mount.

I have not had any problems and I've had this set up going on 3 years. For reference, the axle is a d60 and I have a little over 100 to 1 low low.

Ray

There has been quite a bit of discussion and experimentation about using a single link traction bar. Basically, it partly works and partly doesn't work. If you have very slight spring wrap adding one link to the top of the pumpkin may cure the spring wrap, as it will try to limit the rotation of the pumkin.

Why this is not a guarenteed solution to spring wrap is because the pumpkin can still rotate at the bottom. Spring wrap is when the leaf spring distorts into an S shape, then springs back. With a single link from the top of the pumpkin, the front of the leaf spring can still compress under a hard torque load so the leaves can still warp in the shape of an S, so you can still generate spring wrap with this type of traction bar setup.

The ladder bar design, fully attached to the axle tubes with one pivoting mount at the frame, absolutely will not let the pumpkin rotate. Mine uses two poly bushings at the axle, and two heim joints at the frame. The heims are mounted through each other, so it can move forward/backward, side to side, and twist, but it cannot move up and down. It's mounted to the rear of my skid plate mounting bracket. Here's a pic:

http://fototime.com/AF00FF54D411945/standard.jpg

The Sam's Off Road style is definitely a better way to go.

Sam's Off Road can make me there HD Traction Bar w/ Johnny Joints at all attachment points. Is this worth the extra coin or will the Poly's at the axle be good enough? The only reason I was looking into JJ's is because of the extra flex they would give & I would think they would be stronger too. Any thoughts to this?