Traction Bar for a Ford 8.8

I have a Ford 8.8 and yes I know it has c-clips and the tubes twist under lots of stress. I dont want to hear about how I should have gotten another axle. This is a debate on how to construct a good traction bar with what axle I am running and lots of other people are running also.

So what I was thinking of doing was building a truss to go from one axle tube to the other and attaching it to the center section as well. The tubes will be fully welded to the center section. This will connect both tubes and pumpkin together. A ladder type traction bar will connect to the driver side of the axle due to the exhaust on the passenger side and will connect partly to the truss. The body end would be a custom cross member and would spread the force out over a large area. The body end of the traction bar would have a Johnny Joint on it to relieve bind when the suspension articulates. Also a shackle would used so the bar can move with the arc of the leafs.

Now the big questions:
1. What issues will there be with the truss and traction bar mounting points on the axle?
2. Will a single JJ on the body end be enough to keep bind at a minimum with the shackle?
3. Now the million dollar question: How does one factor in good anti-squat characteristics? From SEARCHING on POR and theres mixed opinions on what is best. Some say longer the bar the better, then some say it needs to be in the same plane as the front leaf mounting bolts. Then also should the bar be at the same angle as the drive shaft or be as parallel to the ground as possible. What gives and then WHY?

Thanks,

AARON

I'm not sure a truss is necessary. I have the same axle now and am going through the same issues trying to make a good effective traction bar. I will be putting the bar on along with a d60 but that's not the issue. Unless you are doing some heaving jumping, etc. I don't think you need a truss. If all your worried about is you tubes spinning, just weld them to the centersection and be done with it. The 8.8 tubes are thick enough that they shouldn't bend without some serious help.

I'm not sure what the anti squat thing is all about either. I think that one jj at the shackle end will be fine. How much flex do you get out of the rear springs anyway? I personally like the bar running parallel with the dshaft. It kinda adds some protection. If you have read all the posts and opinions, one stands out. Make it, try it, break it, make it again...different. What works for one, won't necessarily work for another.

MrShoeBoy said:

1. What issues will there be with the truss and traction bar mounting points on the axle?
Build the truss to span all the way out to your spring pads. You see too many pictures of truss' mounted just beyond the cast center section. Wider is better. Use a flat plate gusset under each side to support more of the tube. For the traction bar, 6" or so vertical distance between the mounts at the axle end should be fine. Make sure one joint is adjustable for setting pinion angle.

2. Will a single JJ on the body end be enough to keep bind at a minimum with the shackle? The JJ sounds good if this a trail-only rig. Otherwise factory style rubber bushings will help with NVH.

3. Now the million dollar question: How does one factor in good anti-squat characteristics? From SEARCHING on POR and theres mixed opinions on what is best. Some say longer the bar the better, then some say it needs to be in the same plane as the front leaf mounting bolts. Then also should the bar be at the same angle as the drive shaft or be as parallel to the ground as possible. What gives and then WHY? What are good anti-squat characteristics? Judging by the reports back from Moab, it looks like WonTonTomato and Beezil found a good AS%. I think the figure posted was 87%. Right at 100% sounds good at climbing angles so 87% on flat ground makes sense.

Click to expand...

Thanks.

I am thinking about the truss so the added forces caused by the traction are spread out over the whole axle and not just the one axle tube and the center section. With the truss, both tubes and centersection would share the forces. I was just wondering if there would be any negitives with this but I cant see any.

Why is a JJ only a good idea if this is a trail only rig? Is this just for the fact that they will transmit vibes into the cab? I have JJs on the frame end of my long arms and poly at the axle end and have not noticed any negitive effects or excessive vibes with them.

I am still fuzzy on the whole anit-squat thing. What was the post that Beezil had that explained it really well? I want to do my homework the first time around because I dont have the funds to try it, break it, build it again. Build it once build it right!

Thanks,

AARON

I don't see how a traction bar will effect anti-squat.....but it might in a way that I'm not thinking. Anti-squat comes as a result of torque working against upper and lower links. A traction bar is only one link, and it moves at the front, so I don't see any anti-squat force involved.

One problem that has shown up with the 8.8 is the thickness of the tubes, they are big to resist bending, but thin and the force of a traction bar can rip the tube. I think all you need to do is make sure the lower mount goes as far around the tube as possible to spread the load. Doing this and putting the upper mount on a truss should work real well.

I think the other links may be considered the leaves Richard. but I don't really understand the whole anti-squat thing either. I didn't even realize it was an issue untill after I built mine. In reality its not like you have a whole lot or room under there to make everything match up.

Regarding the tearing tubes. The tore tube was a poor design problem :angel: As you can imagine the mount on the tube translates alot of torque. The one that tore the tube apart was basically two perpendicular plates welded to the tube so that all the torque was held by the thickness of the two plates and the welds around them. That load need to be spread more.

I cut my bracket out of a piece of box tubing. So the welds are 3 or so inches long around the radius of the tube on both sides of the box tubing and on the top and bottom its about 2.5 inches wide welded all the way across.

I got a little crazy with the plasma cutter

MrShoeBoy said:

Why is a JJ only a good idea if this is a trail only rig? Is this just for the fact that they will transmit vibes into the cab? I have JJs on the frame end of my long arms and poly at the axle end and have not noticed any negitive effects or excessive vibes with them.

I am still fuzzy on the whole anit-squat thing. What was the post that Beezil had that explained it really well?

Click to expand...

I'm speculating on the JJ. Based on the joint construction, they look like a mid-compromise between heim joints and rubber bushings for vibration and noise isolation. With the XJ being a unibody, I don't even like to use poly. YMMV

The only anti-squat post of Beezil's I remember was the one regarding his neighbor. She had a friend in the state legislature that was threatening to pass an anti-squat bill if Beezil didn't quit taking a dump behind his garage.

Richard, the traction bar acts like a radius arm and handles the torque from the rear axle instead of the springs doing so. Axle torque is applied to the sprung mass where the shackle is attached to the chassis and resists the body pitch moment during acceleration. The shackle can move fore and aft, but in the vertical direction where the traction bar is pushing up on the body, it's more or less rigid.

Thanks for all your help. This is a good start

AARON