Anti-Wrap Traction Bar (1 Viewer)

[J Mack]

I’m getting ready to build a new rear end and I’m thinking about adding an anti-wrap traction bar similar to the Ruff Stuff kit. http://www.ruffstuffspecialties.com/catalog/AWKIT.html

I know a few of you guys already have them on your 55’s and I would like to know if there is any down side that out ways the benefits?



Thanks.

 

[tatat]

my first idea is that it gives mor weight to unsuspended parts. Is it important to usual pigs speed?
second. Do you reallyneed it? I assume it is needed when you have an engine with much more torque than OEM or more reduction gear.

 

[J Mack]

my first idea is that it gives mor weight to unsuspended parts. Is it important to usual pigs speed?
second. Do you reallyneed it? I assume it is needed when you have an engine with much more torque than OEM or more reduction gear.

I have no real world experience with traction bars on a 4X4 and you are correct I’m not sure it’s needed.

My 4BT diesel will have around 450+ foot pounds of toque and the transfer case has under drive low range gears so I’m thinking the axel wrap is a possibility and I would rather error on the safe side if the Anti-Wrap/Traction Bar has no ill effects.

 

[J Mack]

Dug some pictures of mine up:

You can see how the brackets and "wraparound" section cover about 2/3s of the axle. If I recall right, the brackets are 1/4" plate. Yes, I've also got sway bars The tubing is all 1.5" DOM .250" wall

What size heim joint is at the end not shown?

Thanks for the photos!

 

[Delancy]

Have been trying to find a post of Don's about this for two days, and can't.

Pretty much hits it on all points, here, though, the only semi-tech I can regurgitate is it's similar to links, in that separation should be 25% of tire size and the flatter the better.

Most of your suspension movement will not be "straight up and down" unless the vehicle is strictly street driven. And on the road it'll only travel 1-2" each way unless you jump the vehicle.
When you're dealing with an off road application, you need to worry about a traction device that can deal with suspension compression and droop as well as articulation.

The pic the OP posted is exactly what you want/need. We've been building them that way for years. It's a design perfected by FC187 and has been tried and tested on numerous cruisers. Including mine .......

Hth

Georg @ valley hybrids

Fwiw.....

1) you do want the top bar to be as close to horizontal as possible or you could run into issues with "dive" or "lift" under acceleration or braking.

2) you want the length of the bar to be as long as the rear driveline or slightly longer for the same reason.

3) the travel of the rear axle ( linear or elliptical ) depends on the arch of the springs and length of the rear shackles.

I know what this stuff looks like on paper. I did go to college for mechanical engineering. Who cares! Real world experience has taught me a lot more about things like traction bars ........


Georg

We use 3/4"x3/4" heims on all three ends of the bar and bushings at the fixed end of the shackle.

Georg

fine. we don't know what the hell we're talking about. we've only been running trails including rubicon for 20 plus years and none of our bars have ever broken off the axle housing or the hanger mount. nevermind that we do this stuff for a living every day..............just a couple of idiots!


i just so happen to have one of quite a few SOA 40s in the shop right now that we built. with one of don's bars in it. i'll jack it up tomorrow and will post some pics.


georg @ valley hybrids



ps: one very simple question for you ed: when is the last time you drove your cruiser and the rear suspension dropped 8" on both sides?

 

[Delancy]

FWIW, Georg and Don are old school, thinking Pighead's TWRECKS the first SOA Pig Don did, as a driveway project, even and don't think there's been any issues in ~20 years he's run.

 

[J Mack]

View attachment 959133

I've been looking at the bars FC builds for inspiration and it appears the he hangs the front shackle the opposite of this illustration. Do you know if one way is better than the other?

 

[Delancy]

Do you know if one way is better than the other?

Whatever way Don does it is better....realizing that doesn't really answer the question.

 

[scrapdaddy]

I ran a set of traction bars on my old 40. It was SOA, 327 chevy and 38" mudders. They were similar to Chris's illustration, seemed to be rough riding on the street, but I even knew less then, than I do now, so...

 

[Delancy]

So obviously not much help

I wasn't discounting what you said, dood.

 

[LAMBCRUSHER]

shackle can go up or down with same effect...Don makes some dam beefy bars...I have been thinking about these as well as I seem to be experiencing some wheel hop out back. I am SUA on some MAF 4" springs...my guess is that if you are high enough, or strong enough, the traction bar is a bonus...,.no drawbacks.

 

[fj55tlc]

I used to think that I didn't need a traction bar. How could a leaf spring with 9 leaves twist that much. Well I could not have been more incorrect. The leaf springs didn't twist in my experience. I was climbing a ledge on about a 40 degree slope. I wasn't even in compound low, which would have been 146:1 with over 30,000 pound feet of torque to the tires, but I was only in low range. The right rear wheel fell into a hole that was dug out in front of the ledge and when I gave it a little bit of throttle to bounce it up the ledge, I twisted the whole rear axle housing. The u-bolts were still in place but I folded the edges of my 5/16" homemade spring perches and the axle rolled. Broke the rear u-joint and snapped off both shocks. When it happened, and I have it on video, both front tires lifted off the gound a few inches. I would have never thought that would ever happen. The pinion was pointed straight up and both rear tires were pushed forward into the sliders. I high lifted off the rear bumper till the weight was off the springs and attached the winch though a snatch block on the rear bumper to the axle to pull it back. I was able to replant the axle and tighten down the u-bolts. All this still on the 40 degree slope. I removed the rear drive shaft and turned the brake proportioning valve down so the rear brakes didn't undo all my hard work. Then I drove it home over 100 miles on front wheel drive at 70 mph. It proved to me that I needed a traction bar.
So for the love of everything holy, please do everything you can not to duplicate my experience.
I used, for the most part, the Ruff stuff kit. I made the whole thing out of 2" dom tube. Yes it's heavy. So is the rest of the truck. I can tell a difference. Even on the street. It feels more solid when under acceleration, even with my worn out 1.5f.
Here is how mine turned out.

 

[scrapdaddy]

fj55tlc,

Would you have a picture of the front mount?

 

[J Mack]

fj55tlc,

Would you have a picture of the front mount?

I would also be interested in photos of the front both fj55tlc's and Lil'John's bars.

I'm looking at Johnny joints for mine but still cant devote enough time to this to fully wrap my head around what I'm needing vs wanting.

 

[Delancy]

I don't know nothin' about nothin' but in the last 5 years of researching suspension geometries, links, so forth, seems that the basic principles of chassis design are the same across the board, from track car to crawler.

One thing that's always stood out is a local chassis builder's schooling on drag car design, saying it embodies best the crawler concept, from geometry to protection.

The way that makes sense to me, is because crawlers are typically loading up suspension in straight lines, but also the premise that it's all the same.

ANYHOW....

I'm tired of researching threads, only to find the link explaining what I need to know, that everyone in the thread cheers, dead....

Dunno if this helps, or not, but saved link from perusals last week and seemed a legitimate concept.

From

http://www.deckersonline.com/fj40_traction_bar


FJ40 REAR (assuming axle is centered on spring)

This drawing shows the Land Cruiser rear suspension as it goes through full suspension travel. The front traction bar mount is located above and forward of the front spring bushing. This location allows the rear of the traction bar to swing in an arc that is very similar to the arc of the traction bar bkt that is welded to the top of the axle. This means that the traction bar is not applying undue force to the top of the pumpkin/axle as it travels in it's arc but is preventing it from wrapping when torque is applied. In other words as the spring is compressed and the axle moves up and back the traction bar follows it because it is swinging in the same arc.
* Note that this drawing is hypothetical as the axle is shown mounted in the center of the spring.


FJ40 REAR (axle is mounted forward of center on spring)

This drawing shows the axle mounted forward of center on the spring as it is from the factory. In order to get the traction bar to swing in the correct arc the front Traction bar mount is still mounted above and forward of the front spring bushing but somewhat lower (just about where the cross member is behind the FJ40 transfer case). Notice that the line that is drawn through the axle and the rear traction bar mount no longer remains absolutely vertical as the spring travels from droop to bump. This is why Toyota mounted the axle forward of the spring centerline. In full droop the pinion is pointing up and in full bump it is pointing down. This would allow for better U-joint angles.

FJ40 REAR (axle is mounted rearward of center on spring)

This drawing shows the axle mounted rearward of center on the spring. This would be the case if the rear springs have been flopped front to rear to get a longer wheelbase hence a better departure angle and longer driveline. Notice that as the suspension moves into droop the pinion is pointing down and as it moves into bump the pinion is pointing up, which will not make for good u-joint angles and will increase the chances of breaking a pinion.
*We don't recommend using our Traction Bar if the rear springs have been flipped or the axle is mounted behind the centerline of the springs.

FJ40 REAR WITH LADDER BAR (axle is mounted forward of centerline)

This drawing shows the axle mounted forward of center in stock position. What I did here was draw a horizontal line 90 degrees to the vertical line that goes through the axle. The solid horizontal lines represents a Ladder Bar that is mounted to the axle but is disconnected from it's front mount. As the axle travels up and down the front of the bar also travels up and down because the ladder bar doesn't have a rear pivot, but rather is triangulated and is fixed to the axle. When the front mount is connected and the front of the bar is fixed vertically (as shown by the dotted lines) it will force the top of the pinion back in droop and forward in bump. This will force the pinion to point toward the back of the transfer case, which is ideal for better u-joint angles, but with the axle bolted solidly to the spring, it will put a twisting force on the springs and the ladder bar. Mounting the rear of the ladder bar to a shackle in the front allows for fore and aft movement, but doesn't allow for up and down movement.

Do I need a Traction Bar or Ladder Bar?

Traction bars and ladder bars are both in use and either will help solve axle wrap problems without obvious consequences. With stock Land Cruiser springs you can probably get away with almost anything because they are so flexy. In short if you're having problems with axle wrap, your pumpkin will be torqueing forward and rearward more without a bar than it would be with one with poor geometry.

During articulation one wheel moves up and one drops down. In this case a ladder bar or a traction bar (even one with poor geometry) will work fine and there will be no spring bind because the axle is pivoting from center, where the bar is mounted. For a dedicated trail rig a ladder bar works great. For a vehicle that is driven on the street or as a daily driver a traction bar may be a better choice. If a ladder bar is fitted to a rig at ride height while unloaded, when it is packed full for a trip, the added weight will change the ride height and cause a forward twist on the springs. If the ladder bar is installed on a loaded rig, the springs will be forced to twist backward when unloaded.

We recommend using our traction bar if you use your rig both on the street and on the trail. You will need to have the stock cross tube behind the transfer case still installed and in good condition, or replace it with a heavier bar. We recommend using a doubler to spread out the load if using the stock cross tube, as we have seen a few failures of the tube where the rear mount for the traction bar is welded. We don't recommend using our bar if the rear springs have been flipped. Our bar will not work on the later model FJ40 with the external gas tank.

 

[Delancy]

Another

I set the front of my wrap bar on a shackle w/ a heim joint and angled the shackle toward the front of the rig, like this /.
So during up travel it'll move forward and down travel, obviously, it'll move back.

Hope that makes sense....

 

[fj55tlc]

I will get a picture up for the front mount this coming week. The bummer is that my cruiser is up at my work waiting for its new engine to show up.

 

[fj55tlc]

Sorry for the delay. Here is my transfer case mount for the traction bar. I have the advance adapters rear cross member which I had to modify because mine is 10 inches further back then they designed it to go. It is fairly thick steel plate, about 5/16". I made a steel plate that bolts on half of the bolt circle on the transfer case. The plate I made is 3/8" steel that I welded 2" square tube to and reinforced that with some more 3/8" steel. The shackle for the traction bar is attached to that. So far so good. It hasn't been on too many hard four wheel trips yet, but I am always trying to put my own engineering to the test. Someday I may get it all right.

Oh, and disregard the bolt that is too long and the rusty shackle. It will be rectified soon.

 

[TuffMudder]

And I continue to Single White Female Jmacks build up (for the record this is coincidental and not an actual case of Pig stalking )...

This thread made my brain hurt. Traction bars are far more complicated than I anticipated. I came on here thinking to find relatively simple answers to my questions, but why I thought that would ever happen is anyones guess.

So, it seems if I make the top arm about the length of the rear drive shaft and mount the front end to either an add in crossmember or skid plate with mount points near the TC rear pinion with the top arm as close to horizontal as possible I should be ok?

Anything else I need to keep in mind for the traction bar?

I plan to go with a Ruffstuff kit. Anyone know the difference between:

Simple traction bar kit
and
Antiwrap/traction bar complete kit

I'm thinking i need the complete kit, but not sure what the difference is (the simple kit is quite a bit more expensive than the complete) nor can i tell if the complete kit has a large enough circumference on the housing bracket to ensure a strong enough weld.

 

[scrapdaddy]

It looks like the Simple traction bar kit is for two bars, like old drag bars. I don't think they are connected. I don't understand this one? Seems like it would bend.

The antiwrap bar is two bars made like Lil' John's. They are made as one unit.