Traction/ anti wrap bar design questions

GWag89 · Post by **GWag89** » Sat Feb 14, 2015 10:29 am

I'm starting to design an anti wrap bar for my wag now that I have Chevy 63" rear Springs and plan on running 33s and a locker in the rear Dana 44.

I plan to make a traditional bar with 3 heim joints (unsure of size). Two heims mounting to the axle side and one on the shackle side. The shackle will be bolted to a hanger that is welded to the factory X member that runs underneath the rear seat. The bar itself will consist of 1.5" or 1.75" .120 -.25 wall dom . 1 main bar ruining from the shackle to the upper heim Mount on the axle bracket. And a shorter angled tube that mounts to the lower heim on the axle .

What angle do I want the traction bar for best performance? Flat? Angled with the drive shaft? Angled with the pinion?

How do the positions of the heims on the axle affect articulation?

GWag89 · Post by **GWag89** » Sat Feb 14, 2015 10:45 am

Here are some ideas I'm tossing around on the axle bracket. I want maximum articulation but don't want to compromise performance of its anti wrap duties.

There are quite a few variables that can be adjusted when designing this bracket. I'm looking for insight as to how these variables affect performance and articulation

Post by **Stuka** » Sat Feb 14, 2015 11:11 am

Having the upper bar over the axle would be better than having it in front. Provided you have shock and brake line clearance.

The bar will limit articulation, no real way around that. But the longer the bar is, the less of an impact it will have on articulation.

GWag89 · Post by **GWag89** » Sat Feb 14, 2015 12:55 pm

Is it better to have the shackle mounted in compression or in tention?

Post by **Stuka** » Sat Feb 14, 2015 3:50 pm

That typically comes down to which fits and gives the best ground clearance.

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GWag89 · Post by **GWag89** » Sat Feb 14, 2015 7:00 pm

Anybody have pics of your anti wrap bar setup?

What works for you? What would you change? Any and all advise is appreciated

Tatsadasayago · Post by **Tatsadasayago** » Sat Feb 14, 2015 7:21 pm

The main design concern is that the bar must move with the axle housing as it travels up and down and rotates during articulation.
Ideally, your bar should be centered over the axle tube and the other end mounting even with the front spring eye.
The rotation affect can be mitigated by moving the front mounting point toward the center of the axle while keeping the rear mount toward the tire. It should also be designed to maintain proper pinion angle during compression and extension if possible.
Ideally, the bar will not bind and will travel in the same arc as the axle.
If you have ever seen a ladder bar setup, they hold to this design. Traction bars did a similar thing but used the forward area of the leaf spring and a contact point instead of a solid mounting location further forward. The kind of bar design you shared is essentially a ladder bar with only the upper tubing. That's a bad thing for a straight line drag car but good for a wheeling rig.
4X4s add the rotation/articulation aspect so some sort of ball and socket mount at the front end eliminates the torsional binding.

If I had my CAD computer here I'd design a link setup for you, but alas I cannot.

GWag89 · Post by **GWag89** » Sat Feb 14, 2015 9:02 pm

Thanks for the tech. That's all good info. I like to design my own stuff if possible . But i don't like to simply copy others design without understanding the principles of the design. Knowing how is not enough. .. knowing why is the ultimate goal.

SJTD · Post by **SJTD** » Sat Feb 14, 2015 9:18 pm

Take a look at Resbum's truck: http://fsjnetwork.com/forum/viewtopic.p ... 1&start=20

He used two but I think the basic design is an example of what you're looking for.

GWag89 · Post by **GWag89** » Sun Feb 15, 2015 9:53 am

Yep resbum design is very close to my own design with only a few small differences.

I only need 1 bar

My rear suspention is built to maximize down travel so I'm thinking of mounting the shackle in tension to allow the axle more droop.

I had planned on using heims on the axle side but am undecided because of price. Not sure if 2x the $$ buys 2x the performance or durability

SJTD · Post by **SJTD** » Sun Feb 15, 2015 11:00 am

Idunno why he used two other than a single one might offend one's sense of symmetry.

In this application it seems to me they don't see much movement so maybe cheaper is adequate?

I don't see where the front to back mounting of the arm at the axle makes any difference. The vertical spacing needs to be enough for adequate stiffness. You are simply making a rigid truss. I'm not sure you even need the spherical ends at the rear. They won't allow the bar to twist relative to the axle. They would allow side to side movement. Maybe polyurethane spring ends would be good enough.

GWag89 · Post by **GWag89** » Mon Feb 16, 2015 2:54 pm

Anyone running a traction bar want to chime in?

68glad · Post by **68glad** » Mon Feb 16, 2015 8:34 pm

Here's mine. (Pay no attention to the wd40 overspray

) 8" separation between upper & lower bolts. 48" long. Homemade poly bushings on axle end and a heim on the shackle end. I don't think heims are needed on the axle end. At least on mine. The amount of swivel needed isn't as mutch as it appears. Got one on the front also. Driving at the dunes through some whoops, without transfer case shifter boot, and about loaded my britches when I saw how much the frontend actually moves. I had this face...

edit: bottom bar matches driveline angle.

Front.

GWag89 · Post by **GWag89** » Mon Feb 16, 2015 8:49 pm

Thanks 68glad. I think I've decided on poly bushings for the axle end and a heim on the shackle

I'm going to try to keep the top bar flat and the lower bar angled with the drive shaft but let it hang an inch or so lower to act as a slider.

Still undecided on shackle orientation?

Jerry Blair · Post by **Jerry Blair** » Tue Feb 17, 2015 7:18 am

I my traction bar on my YJ was built similar to 68glad's. I used what I had in the scrap pile so the axle end used rubber bushings from a track bar and the shackle end uses two rod ends mounted in threaded DOM. I mounted the shackle so that the pulled on it going forward and pushed in reverse.

This bar worked perfectly and controlled wheel hop from soft YJ springs SOA, 37" Krawlers and a warmed-over 302HO.

AwesomeJ10 · Post by **AwesomeJ10** » Tue Feb 17, 2015 8:21 am

Jerry Blair wrote:I my traction bar on my YJ was built similar to 68glad's. I used what I had in the scrap pile so the axle end used rubber bushings from a track bar and the shackle end uses two rod ends mounted in threaded DOM. I mounted the shackle so that the pulled on it going forward and pushed in reverse.

This bar worked perfectly and controlled wheel hop from soft YJ springs SOA, 37" Krawlers and a warmed-over 302HO.

Very nice YJ and very nice traction bar.

Just last week I built a traction bar on my wifes YJ and it came out very similar to yours. The whole jeep is built pretty much like yours, except I do have a 14 bolt back there

To the OP.

Save yourself some time and $$$ and look at some of ruff stuff's stuff. https://www.ruffstuffspecialties.com/ca ... TMAIN.html

I built my first traction bar in the Honcho a few years ago with stuff I had laying around in the garage and it works GREAT, but I've since bent the main part that welds on the axle and need to redo it all. I wish I had went with ruff stuff from the beginning. I did on my YJ and it worked out real good.

Jerry Blair · Post by **Jerry Blair** » Tue Feb 17, 2015 8:31 am

Blake wrote:
Very nice YJ and very nice traction bar.

Just last week I built a traction bar on my wifes YJ and it came out very similar to yours. The whole jeep is built pretty much like yours, except I do have a 14 bolt back there .

Thanks, it is "the one that got away!" I regret selling it every time I see a pic!

AwesomeJ10 · Post by **AwesomeJ10** » Tue Feb 17, 2015 8:39 am

Jerry Blair wrote:
Blake wrote:
Very nice YJ and very nice traction bar.

Just last week I built a traction bar on my wifes YJ and it came out very similar to yours. The whole jeep is built pretty much like yours, except I do have a 14 bolt back there .

Thanks, it is "the one that got away!" I regret selling it every time I see a pic!

oh yeah. I built an '88 GW a couple of years ago, threw a ton of money into, axles, atlas, tires, etc and then practically GAVE IT AWAY just so I could fund the purchase of my wifes TJ.

boy do I miss that thing and I definitely know how you feel.

GWag89 · Post by **GWag89** » Sat Feb 21, 2015 12:16 pm

Here are some options I'm tossing around. I will give full credit to WRO for the adjustable link. Since I'm running 63" Springs with d44s larger axles and more lift is likely so adjustability is key if I want to use the same bar.

You may notice the shackle hanger has 4 holes for adjustment. That is there so I can adjust the mounting point when I move my axle.

Jerry Blair · Post by **Jerry Blair** » Sat Feb 21, 2015 9:26 pm

GWag89 wrote:

I like options 1 and 2. Those are the strongest. The other designs that have one bar much longer than the other will be prone to bending. When I built my bar it looked a lot like #3. I used 3/16 plate to sandwich the longer bar all the way from the Y to the shackle. I had seen previous examples bend on designs used by competition rock crawlers back in the day.

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