OK Cliffy. So what is the plan? How are you using your trailing arm as an anti wrap? I read your post about having the spare trailing arm, but did not put it together with using it for an antiwrap system like we talked about. What's the scoop? :)

Well the items I have are 2.5"x2.5" 1/4" wall box. They are about 4ft long and have a spring eye end bolted to them. The bushings in those spring eyes are already shaved down at the ends (like a football) to prevent binding.

My thought was to add a crossmember and a shackle typoe set-up. The only different thing here would be that you would want the anti wrap bar mounted above the crossmember to avoid loosing GC, due to the design of the bar.

Notice in the pic how the spring eye end is on TOP of the bar. You could just flip the bar over, but I think this way would minimize GC loss also.

PS: Remember I said I'd ship it to ya for just the cost of shipping ;)

Use this a reference for your talks.

Originally posted by Cliffhanger
Well the items I have are 2.5"x2.5" 1/4" wall box. They are about 4ft long and have a spring eye end bolted to them. The bushings in those spring eyes are already shaved down at the ends (like a football) to prevent binding.

My thought was to add a crossmember and a shackle typoe set-up. The only different thing here would be that you would want the anti wrap bar mounted above the crossmember to avoid loosing GC, due to the design of the bar.

Notice in the pic how the spring eye end is on TOP of the bar. You could just flip the bar over, but I think this way would minimize GC loss also.

PS: Remember I said I'd ship it to ya for just the cost of shipping ;)

I thought a single bar would not work? I thought it had to be a ladder type setup?

Are you thinking inboard or outboard of the springs?

Originally posted by Hooper


I thought a single bar would not work? I thought it had to be a ladder type setup?

Are you thinking inboard or outboard of the springs?

Inboard and as close to the pig as possible.. :D

Learned that the hard way:(

I definitely don't think you could use a single bar if you talking about heim type connections, but These bars seems to zero out my axle wrap on the blazer.

Inboard of the springs. I was thinking on the pass side of the diff. That's where it would work best on my 14bolt.

How would you allow for the rotation of the axle in this setup? Don't you need at least one heim in the system?

Originally posted by cornfedred


Inboard and as close to the pig as possible.. :D

Learned that the hard way:(

What happened on yours? Too much droop twisted everything up, right?

Originally posted by Hooper
How would you allow for the rotation of the axle in this setup? Don't you need at least one heim in the system?


All heims or Johnny.. The only bushing is in the lower shackle mount

Originally posted by Cliffhanger
I definitely don't think you could use a single bar if you talking about heim type connections, but These bars seems to zero out my axle wrap on the blazer.

Inboard of the springs. I was thinking on the pass side of the diff. That's where it would work best on my 14bolt.

Have to use heims to allow the rotation of the axle.

On the setup cliffhanger is describing, the trailing arm acts exactly like the ladder bar.

Imagine you added a 3rd spring perch to your axle housing, then the trailing arm is u-bolted to the top of the spring perch, with a bolt in it acing as a centering pin. Now, the trailing arm moves with the axle, and the axle cannot wrap with out the forward end of the trailing arm moving upward. Attach the forward end of the trailing arm to a shackle and you have created your ladder bar/shackle arrangement.

what about the PM style?

http://www.partsmikeparts.com/WCparts.jpg

Originally posted by Old Scout
what about the PM style?

http://www.partsmikeparts.com/WCparts.jpg

Which end attachs to the tube? Do you run one or two?

you only need one and the tube end in on the left.

Hey Scouter you still have that pic of one installed?

Originally posted by Hooper
How would you allow for the rotation of the axle in this setup? Don't you need at least one heim in the system?

Originally posted by Cliffhanger
The bushings in those spring eyes are already shaved down at the ends (like a football) to prevent binding.


I thought it was clear there, but let me add:

"The bushings in those spring eyes are already shaved down at the ends (like a football) to prevent binding during axle articulation."

I'm assuming by ROTATION you mean ARTICULATION.

If you mean rotation the other way, this is what we are trying to PREVENT.:rasta:

Nothing against PM but I've heard those DON'T work :confused: Although I've never run them...

Originally posted by Ben W
On the setup cliffhanger is describing, the trailing arm acts exactly like the ladder bar.

Imagine you added a 3rd spring perch to your axle housing, then the trailing arm is u-bolted to the top of the spring perch, with a bolt in it acing as a centering pin. Now, the trailing arm moves with the axle, and the axle cannot wrap with out the forward end of the trailing arm moving upward. Attach the forward end of the trailing arm to a shackle and you have created your ladder bar/shackle arrangement.

EXACTLY!!!:smokin:

Originally posted by Old Scout
you only need one and the tube end in on the left.

Hey Scouter you still have that pic of one installed?
PM bar on my past Jeep. The bar works very well if installed correct.

Here's a couple of pics

front cross member pic.

another

last

Originally posted by Scouter

PM bar on my past Jeep. The bar works very well if installed correct.

call me stupid, but if there is a pivoting joint, using a single bar, AT the axle how does this control wrap??:confused:

Due to the nature of leaf springs, don't the springs keep the pinion angle virtually the same throughout their cycle? (assumedly horizontal) The only time the pinion gets out of angle is when the springs *S* under torque, correct? That antiwrap bar is trying to rotate the axle as it swings through its arc, and the springs are trying to keep it straight, under compression or droop, the springs and anti wrap bar will be fighting each other? The reason ladder bar with 2 pivots at the axle and one on the shackle works is because it allows the springs to dictate the pinion angle on compression and droop, but won't allow the pionion angle to change if the spring compression does not change.

Look at the arrow through the axle in the top picture.

Then look at the arrow through the axle in the bottom picture with the springs slightly compressed. The angle between the pinion and the antiwrap bar is constant since the bar is welded to the housing. The antiwrap bar has forced the axle/pinion to rotate away from where the springs want to be. They are going to cause the springs to S under articulation.

http://www.ihssii.org/Hooper/Images-Technical/WeldedAntiWrap.gif

The A-frame ladder bar, and the bar as I described above will behave identically. Both are fixed in their relationship to the axle housing. Both will remain at constant angle relative to the pinion throught out the axle's range of movement. Both eliminate axle wrap by preventing the axle housing from twisting about the axle shafts when torque is applied. Both allow full articulation due to the heim or bushing at the forward end and the shackle.

I'm pretty sure a ladder bar set-up would work the same way.

In a 4 link set-up (like BELLY DRAGGERS) the front bars are VERY Similar to the yellow ladder bar shown above.

Belly stated in one post that his Driveshaft has only 1/8" of slip. He said that it was due to his bars being the same length as the DS and that the bars kept the pinion pointing @ the X-fer case throughout the cycle of the suspension.

Originally posted by Cliffhanger


call me stupid, but if there is a pivoting joint, using a single bar, AT the axle how does this control wrap??:confused:

It will control wrap because if the axle tries to rotate, the opposite end of the bar will need to go up, but the shackle pins that end of the bar so it cannot rise.

Originally posted by Ben W
The A-frame ladder bar, and the bar as I described above will behave identically. Both are fixed in their relationship to the axle housing. Both will remain at constant angle relative to the pinion throught out the axle's range of movement. Both eliminate axle wrap by preventing the axle housing from twisting about the axle shafts when torque is applied. Both allow full articulation due to the heim or bushing at the forward end and the shackle.

Hmm, that's right. Since the ladder pins at two places, and the angle between the bars cannot change, then the angle between the bars and the pinion cannot change........ because for that angle to change, the angle between the bars would have to change.....

But, you still need a heim at the top....

Originally posted by Hooper


Hmm, that's right.

But, you still need a heim at the top....

But with my set-up you do not. That's where the FOOTBALL shaped bushings come in.

Originally posted by Cliffhanger
another

How much does that thing weigh? Lets figure out how much freight is going to be.....

Where are you again?

Originally posted by Cliffhanger


But with my set-up you do not. That's where the FOOTBALL shaped bushings come in.

Don't follow. How do those help?

I know it's not curved much, but consider that it sill "Squishes" when pressure is applied.

Not neccesarily. A poly bushing will allow some twist, Cliffy has said he shaved the bushing, most likely into an oval shape, which would allow even more twist. You could also use a 'goofy' shackle, which is a shackle that can bend in both the X and Y axis'. A 3rd option would be to use a jonny joint.

Originally posted by Hooper


Don't follow. How do those help?

I don't know how to explain this, can someone help me out here??

Originally posted by Hooper


How much does that thing weigh? Lets figure out how much freight is going to be.....

Where are you again?

I don't know, it's pretty heavy. 35-50lbs. I could CUT it down to a specified length (under 4ft) to drop some weight before shipping.

Originally posted by Ben W
Not neccesarily. A poly bushing will allow some twist, Cliffy has said he shaved the bushing, most likely into an oval shape, which would allow even more twist. You could also use a 'goofy' shackle, which is a shackle that can bend in both the X and Y axis'. A 3rd option would be to use a jonny joint.

Yep. some twist, but not much. I think it would start restricting a well articulating axle.

Take Scoutillac's rig, for example. Mine obviously does not flex like that, but his axle must rotate 50 or 60 degrees from the angle of the frame. A bushing would not allow that.

If you start talking goofy shackle and such (not sure what a jonny joint is) wouldn't a heim work equally well? (I already have one)

Originally posted by Hooper


Yep. some twist, but not much. I think it would start restricting a well articulating axle.

Take Scoutillac's rig, for example. Mine obviously does not flex like that, but his axle must rotate 50 or 60 degrees from the angle of the frame. A bushing would not allow that.

If you start talking goofy shackle and such (not sure what a jonny joint is) wouldn't a heim work equally well? (I already have one)

These trailing arms allowed my axle to twist about 30-40 degrees in relation to the frame. But they would not be the best idea for a buggy spring, 4-link or other seriously RADICAL set-up.

That's also why they will work good for me. Remember it's not like you HAVE to get this...just wanted to present you with an option.

How about this: I'll set it up on my rig. Flex it up, take some pics and we'll see if you think it'll work for you.

Shaving the bushing allows it to twist side to side without deforming. It is basically a budget jonny joint. Here is a jonny joint:

http://www.allprooffroad.com/pics/3515.jpg


I'm not saying any one method works better than another. I was just pointing out the options. If you have a heim already, by all means run with it.

Originally posted by Ben W
Shaving the bushing allows it to twist side to side without deforming. It is basically a budget jonny joint. Here is a jonny joint:

http://www.allprooffroad.com/pics/3515.jpg


I'm not saying any one method works better than another. I was just pointing out the options. If you have a heim already, by all means run with it.

Agreed....

Also, if you have bushings anywhere in you anti wrap system, they will deform enough to allow a small amount of wrap, where heims are rigid and will be more solid. It is debatable whether or not a small amount of wrap is desirable or not.

Originally posted by Ben W
Also, if you have bushings anywhere in you anti wrap system, they will deform enough to allow a small amount of wrap, where heims are rigid and will be more solid. It is debatable whether or not a small amount of wrap is desirable or not.

Better to have a little give then :nuke:

How much wrap is too much, less then 15 degrees of rotation should not hurt anything:question:

Originally posted by Cliffhanger


call me stupid, but if there is a pivoting joint, using a single bar, AT the axle how does this control wrap??:confused:
Look at the pic of the PM bar, it has a stop on the front where the shackle is and the bar cannot get longer. The pinion raises under power, the bar cannot get longer and wrap is controlled.

IMO 15 degrees would be too much. The goal would be to eliminate the wrap induced hopping without being overly rigid. I don't think there is a hard # to quantify it with. Its a trial and error thing.

Originally posted by Cliffhanger


These trailing arms allowed my axle to twist about 30-40 degrees in relation to the frame. But they would not be the best idea for a buggy spring, 4-link or other seriously RADICAL set-up.

That's also why they will work good for me. Remember it's not like you HAVE to get this...just wanted to present you with an option.

How about this: I'll set it up on my rig. Flex it up, take some pics and we'll see if you think it'll work for you.

Sounds good. Mostly I like the discussion of the how and why. I had been thinking that the ladder bar would allow the pinion to bar angle to change. Now I realize that is not the case. It was a good discussion for me.

Sure, strap it on your rig and lets see how it works. A 30-40 degree angle is pretty good on an axle for rigs like ours.

Ben, wasn't there a discussion on the 4x4 list that a single bar would not work? I missed the thread, but someone summarized it as such. Did you follow that thread?

Originally posted by Ben W
IMO 15 degrees would be too much. The goal would be to eliminate the wrap induced hopping without being overly rigid. I don't think there is a hard # to quantify it with. Its a trial and error thing.

I'm with Ben on this one. That is way too much. We are not talking ujoint angle problems. We are talking hop caused by that pinion angle change. I am thinking minimal pinion rotation is the goal. The small amount from bushings should not be an issue. That would be in the degree or half degree range I would think.

Originally posted by Hooper

Ben, wasn't there a discussion on the 4x4 list that a single bar would not work? I missed the thread, but someone summarized it as such. Did you follow that thread?

A single bar is one that has a bushing or heim at both ends of the bar. The angle of the bar is not fixed relative to the axle housing. W/ that system, when torque is applied, the housing rotates about the bushing rather than the center of the housing and wrap can be amplified.

Read this:

http://www.outdoorwire.com/4x4/jeep/tech/susp/axlewrap/

Originally posted by Ben W


A single bar is one that has a bushing or heim at both ends of the bar. The angle of the bar is not fixed relative to the axle housing. W/ that system, when torque is applied, the housing rotates about the bushing rather than the center of the housing and wrap can be amplified.

Read this:

http://www.outdoorwire.com/4x4/jeep/tech/susp/axlewrap/

So they were talking heims at both ends. Makes sense that it would not work.

Why don't more folks go with single bars rather than ladder bars?

Originally posted by Hooper


So they were talking heims at both ends. Makes sense that it would not work.

Why don't more folks go with single bars rather than ladder bars?

Because single bars don't work, unless you have very little torque, aka 4cyl engine.

If by single bar you meant the trailing arm thingy acting as a ladder bar, then I'd say more people don't go with that design because it would be easier to bend.

Why not just use the same design as a four link, but only use the upper two bars. But then you are half way there to a 4 link, migth as well add the two lower bars and double shackle the springs, ala Jim Weed's design

BTW OFC does not have the page listed anymore, what's up with that?

http://www.off-road.com/~jweed

I *might* be stating the obvious here, but a single arm, with heims at both ends, could still *theoretically* work to stop axle wrap. Its line of action must, however, NOT intersect the axle tube. If mounted above (or below) axle centerline, it becomes a tension/compression member, and forces an opposite and equal tension/compression into the leaf springs, forming a force couple to restrain the axle. It is questionable whether sufficient stiffness of such a system can be obtained, in practice, without substantially sacrificing articulation degrees of freedom.

If one wishes to use merely a single arm, and to also mount it directly to the axle tube, then a moment resisting connection must be built, so that the axle tube is restrained to the arm, such that they must rotate together. Hooper demonstrated this before, by pointing out that the upper end of the arm tries to swing in an arc when the pinion rolls up, but cannot do so due to the shackle at the upper end of the arm.

For what it's worth, it seems like everybody here understands all of this, but has some trouble communicating that fact to everyone else. We're all "preaching to the choir", I think....We should all be mechanical engineers, yes? :D

Originally posted by Bindernut


For what it's worth, it seems like everybody here understands all of this, but has some trouble communicating that fact to everyone else. We're all "preaching to the choir", I think....We should all be mechanical engineers, yes? :D

That's my biggest problem, I can visualize most things I just can't explain why it works.....oh well

Hooper, we'll do it that way then. It'll be a little while before I add it, but right now it's the best/cheapest idea I can find.

Originally posted by Ben W


If by single bar you meant the trailing arm thingy acting as a ladder bar, then I'd say more people don't go with that design because it would be easier to bend.

This is very true. When I first designed this trailing arm and coil spring set-up for my blazer, I used thinner wall tubing and bent them while fooling around in a PARKING LOT :eek:

Since I upgraded to the 1/4" wall, I never had a problem. *but I also didn't get a chance to wheel it that much either*

Anyway, we'll see. I'll test it, then do a follow-up thread ;) :beer:

Originally posted by Ben W


Because single bars don't work, unless you have very little torque, aka 4cyl engine.

If by single bar you meant the trailing arm thingy acting as a ladder bar, then I'd say more people don't go with that design because it would be easier to bend.

Yep. Trailing arm welded to the tube is what I meant. I was kicking the idea around with Rusty last night and he said the same thing. Weight for weight, the A frame ladder system gives better leverage for the weight.

Interested in seeing how Cliffy's trailing arm works out though. It is a *simpler* system to install.

I think....We should all be mechanical engineers, yes? :D

Do they get paid much??? :) I wasted a lot of time at the U taking calculus, diff calc, physics and engineering, and then went into sales.

Wonder if I should go back and finish my engineering degree?

Naw. Too old. I have forgotten how to read....

I was confused at the start of the thread, forgetting that an A frame ladder bar also restrains the pinion to ladder bar angle, so this has been a good thread for me. Helped to have to think through, and talk through the physics behind the anti wrap bars, even if it was a little elementary for PBB. ;)

Now, can we get back to the really important stuff, like why my muffler bearings don't work? No, I am not going to tell you what engine, what make, number of cylinders, ignition system, carb system, or the color of my floorboards. This is PBB, you guys should be able to figure that out on your own!!! :D

Well Patrick, when was the last time you took an exhaust sample? :flipoff2:

Tim in KS

Originally posted by Tim in Ks
Well Patrick, when was the last time you took an exhaust sample? :flipoff2:

Tim in KS

Still waiting for the blisters on my lips to heal from the last one..... Am I doing it wrong? ;)

Originally posted by Hooper


Still waiting for the blisters on my lips to heal from the last one..... Am I doing it wrong? ;)

I'm not even going there.......


:eek:

Originally posted by Hooper
Weight for weight, the A frame ladder system gives better leverage for the weight.


Don't you mean weight for STRENGTH? :D

DUH! :flipoff2: Ever heard of Mc/I ?? The maximum bending moment needing to be resisted by the arm occurs right at the axle tube, and tapers off linearly to zero at the upper end of the arm. The A-arm setup has the greatest depth in the direction of bending AT THE AXLE TUBE, meaning it has the greatest moment of inertia, I, right? :D This means that for the same bending moment, the stresses in the a-arms are LOWER than they'd be if you had a prismatic (i.e. constant cross-section) bar for an arm, since the prismatic trailing arm is nowhere near as deep at the axle tube. Therfore, the stresses are much higher in a prismatic arm. Obviously, with lower stresses you can use a lighter section to carry them, without being as concerned with buckling, etc...wheras a high stress section requires thicker walls and overall heavier section.....so, yeah...

Come awn, this is basic mechanics of materials, you guys. We all learned this stuff in kindergarten, plus we were born with an inherent understanding of the concepts. why is there even a discussion? :flipoff2: :D

(Before somebody takes me too seriously and soils their briefs, I'll say lighten up and have a :beer:.)

This basic engineering lesson (aka razzing) brought to you by the letters F,A,Q, and the number 3.141592653589793....

Originally posted by Bindernut


Don't you mean weight for STRENGTH? :D

DUH! :flipoff2: Ever heard of Mc/I ?? The maximum bending moment needing to be resisted by the arm occurs right at the axle tube, and tapers off linearly to zero at the upper end of the arm. The A-arm setup has the greatest depth in the direction of bending AT THE AXLE TUBE, meaning it has the greatest moment of inertia, I, right? :D This means that for the same bending moment, the stresses in the a-arms are LOWER than they'd be if you had a prismatic (i.e. constant cross-section) bar for an arm, since the prismatic trailing arm is nowhere near as deep at the axle tube. Therfore, the stresses are much higher in a prismatic arm. Obviously, with lower stresses you can use a lighter section to carry them, without being as concerned with buckling, etc...wheras a high stress section requires thicker walls and overall heavier section.....so, yeah...

Come awn, this is basic mechanics of materials, you guys. We all learned this stuff in kindergarten, plus we were born with an inherent understanding of the concepts. why is there even a discussion? :flipoff2: :D

(Before somebody takes me too seriously and soils their briefs, I'll say lighten up and have a :beer:.)

This basic engineering lesson (aka razzing) brought to you by the letters F,A,Q, and the number 3.141592653589793....


Ahh, now I know what was wrong with what I was thinking. I had PI as 3.14159265358974... instead of 3.14159265358973...


Got it now. Thanks.

Next topic please. :D

ROFLMFAO!!!!!! Yeah, that was probably it. :D :beer: :D :flipoff2: :beer:

How long should anti wrap ladder bars be? I realize that longer bars have better leverage and you can get away with *weaker* connections on the upper shackle. But, I can get my hands on some Sch 80 with heim nuts already welded in place, ready to go. 21 inches long. Not sure if that is long enough for what we are doing though. Seems like that should be roughly the same length as the front half of the rear springs, so if pinned the bars roughly where the front springs pin, wouldn't that give us roughly equivalent arcs, with the shackle allowing for the small discrepancy?

Shorter ladder links would place more strain on the shackle connection, but would allow less deflection of the actual arms. Kind of a trade off, right? Less likely to bend an arm, more likely to rip the shackle mount off if it was not secure?

Shorter bars are more likely to cause the rear of the vehicle to lift under power, longer bars are less likely.

Originally posted by Ben W
Shorter bars are more likely to cause the rear of the vehicle to lift under power, longer bars are less likely.

As the axles torque and try to drive the pinion down, the weight on the ends of the ladder bars pushes the backside of the diff to keep it from rotating. If the axles push hard enough, they can exert enough force to counter that weight, and the pinion will still drop (although it is not likely to hop?) Since the ladder bars attach toward the rear with shorter bars, the torque only has to lift the rear frame and tub. Longer bars attach toward the middle of the vehicle, so to counter the weight, they have to lift more vehicle weight, rather than just the rear portion.

So, longer bars allow less vehicle lift.

If I *try* the shorter arms and it doesn't work, the attachment at the axle side could still be used for longer arms. But, I would have to rework the upper shackle end.

Hmm, more to think about. Gotta get some narrower mufflers first. Then figure out the shackle connection, then,,,,

I think you're confused. On the rear axle,axle wrap causes the pinion to go up. On the front axle, axle wrap makes the pinion go down.

Originally posted by Ben W
I think you're confused. On the rear axle,axle wrap causes the pinion to go up. On the front axle, axle wrap makes the pinion go down.

Yep. I was upside down. Sorry. Sooo, if acceleration makes the pinion try to rotate up, the distant end of the arm attached to the shackle tries to rotate, one vector of which is upward, so it tries to lift the weight of the rear of the truck through the arm, through the shackle, through the shackle connection. The longer arm provides more leverage to counter that force, and it increases the load the arm has to lift because it is closer to the center of the frame, rather than rearward.

How much can it really lift it though, because after just a couple degrees of rotation, the arm reaches a point where the shackle is in line with the arc the arm is trying to swing, and the arm cannot pull any farther, so the pinion cannot rotate any farther. Course, that is when the arm faces the maximum bending moment, also, and a long arm is more susceptible to bending then a shorter....?