Engine/Transmission (1998.5 - 2002) Wrap up bars and rear wheel hop

[Jonz]

Has anyone found wrapup bars for the 2001 4x4. While off-roading I get terrible wrap up and have not found anything worthy to do the job.



Thanks all... .



Troy

 

[BLACKRAM]

Contact Steve St. Laurent.

 

[Jonz]

Steve who?

I would love to contact him..... but have no idea who he is... .



Troy

 

[JR2]

He is the head moderator on the boards, his email is at the top of the board right now. But don't bother contacting him as he got out of the traction bar business.

 

[PROSTAR190]

Check out Dave Mitchell.

 

[curatchko]

Well... .



Since you all started the subject, this is something that has been bothering me with my truck for a while. So I was going to make my own.



The thing to remember is that anything that does not pivot on the front eye of the spring, will bind the suspension. To what degree depends on the condition, but the 2 points of the rear suspension, between the front eye, and the perch are fixed. There is no spring action between those two points. So a bar could easily be made to mount at the front eye, and extend up on top of the axle tube or something... .



That's as far as I've gotten... anyone else have any thoughts??

 

[Steve St.Laurent]

Actually, that's not the case curatchko. If you did what you are saying (have a bar that is the length between the front spring eye and the axle) you would bind your suspension BIG TIME. I spent over a year researching ladder bars before I worked with a monster truck builder to design a set for our trucks. We have springs that are mounted in a fixed position at the front and with a reverse shackle at the rear. When your suspension moves upward a couple of things happen. First, the distance between the front eye of the spring and the axle lengthens because of the spring flattening out (hence the reason that what you said would bind the suspension - the spring would have to retain the same bend as the suspension move, therefore you'd be eliminating the front half of the springs). Second, as the axle moves upwards the rear eye of the spring moves down (because of the reverse shackle) and therefore the axle rotates clockwise (as seen from the drivers side). So the length, angle, and the design of the bars has to be such that it allows the axle to move rearward in the chassis as well as rotate backwards slightly. Depending on your use of your truck you also have to consider axle articulation.



When we did the design of my bars they spent hours working up formula's to figure out what looked like the optimal length and angle of the bars (after we had decided on where they were going to mount on the axle, type of mount, type of ends, etc). Then they used a fork lift and weight in the bed to articulate the suspension and make sure there was no binding (since I off road my truck all the time). Once they were finished we again used the fork lift and weights in the bed and had the same amount of articulation as we did before the bars. BTW, just eyeballing it the forward mount of the bars is approximately 14 inches ahead of the front spring eye.



I sold 18 sets of my ladder bars and everyone was happy with them as far as I know. Unforetunately because of the quality of materials used they were considered by many to be too expensive (~$500). Even at that price I lost money after selling 18 sets. It took too much of my time to put them together and that time was better spent doing other more profitable ventures. I am planning on putting together an article for the magazine that will give full installation instructions as well as parts sources so that you can buy the individual pieces yourself to make them.

 

[curatchko]

Well, the way I understand how a leaf spring works, the spring is fixed between the front eye, and the perch. The only spring action is between the rear shackle, and the perch, because the rear eye is floating. The front eye is the pivot point for any spring articulation, because these two points are 'fixed'.



Front of spring is takes the drive load, rear of spring takes compressive loads from the truck.



Anything that binds the geometry in the suspension, is due to conflicting geometric points. If you have a common geometric point, ie... the front eye, then there should not be bind. Both the leaf, and the bar would rotate on the front eye.



All ladder bars that I've seen for trucks, WILL conflict with the geometry of the rear springs. This is one reason they are so long, that the arc is large enough that it doesn't affect the geometry enough to notice... bushing deflection, flexing of parts etc take up the slack.



BUT, I don't care what ladder bar you have, it will bind suspension unless you float the leafs. You can simply create a ladder that has 'minimal' effect on the geometry, and that's the best you can do.



This is why I'm not interested in a ladder bar. I'm interested in a bar with 2 points, not 3 like most ladder bars. One point being at the front eye, and another mounted above the tube or near the perch, or even below the tube. There can be 'zero' bind in this case. But, this would eliminate any spring 'wrap'. The wrap occurs between the front eye and the perch.



I also have Ladder bars on my race car. So I'm familiar with them as well.



I have worked as a suspension engineer for GM Truck so I am not completely ignorant on the subject.

 

[Steve St.Laurent]

Mine do have two points instead of three as on most ladder bar setups. Here is a post that I made on an old thread discussing the different styles of ladder bars that were available and the issues I had with them:

I'm not trying to sell anything here guys but just want you to be aware of the potential issues with different ladder bar setups so you can make informed decisions. Ladder bars have to be designed properly in order to allow for proper suspension articulation (for now I'm mainly talking about both tires moving in unison - ie on the street, although this also affects being able to "cross-up" the suspension) otherwise you will get suspension bind.



As your axle moves upward (relative to the frame) it has to also move rearward for two reasons. The leaf springs in the rear are attached solidly at the front and with a hanger at the rear, because as the axle moves upwards the leaf spring pack gets longer (measured from eyelit to eyelit) hence moving the axle rearward, the axle housing also rotates some rearward because of this.



If you have ladder bars that have a fixed mount at the axle (either clamped to the axle or attached at two points on the axle) then you have to have a shackle mount at the front mounting point of the ladder bars to allow this and it has to be properly designed (geometry equations - as with ANY good ladder bar design) - if you have a solid mount at the front and a totally solid mount at the rear (2 mount points or a clamp style mount) then you have virtually eliminated any suspension travel you would otherwise have - read rough ride and hard on parts. The biggest problem with this style of bar (fixed mount at the axle) is that when you put a heavy load in the truck or behind it that will settle the suspension you are either 1. putting a HUGE stress on the mounting points for the 2 point type bars or 2. putting a HUGE load on the clamp on the bars and in order for the rear end of the truck to sag the clamp will have to slip around the axle.



Also, many of the ladder bar setups out there require you to remove your anti-sway bar. Ladder bars DO NOT replace the function of an anti-sway bar, unless they restrict your suspension travel - in a way that's kind of what an anti sway bar does. Ladder bars should only locate the axle fore and aft (with the proper amount of rearward movement of the rear axle to allow for proper suspension travel) and not in any way shape or form stop the left side of the axle from moving upwards versus the right (full suspension travel). An anti-sway bar simply applies resistance from one side of the axle moving without the other doing so (but still allows flex and suspension travel - although less than if it was removed or disconnected, hence the sway bar disconnects that are sold to off roaders).



Also, AFAIK all of the off the shelf retail ladder bar kits out there use bushings for their attachments (I could be wrong on this though) and at least some of them are very wide. A bushing restricts the amount of twist that a ladder bar can produce which can reduce travel in a "crossed up" suspension. For most diesel drivers that is not a consideration - but some of us do off road and that's when this becomes a concern.



Last point is that there are different quality components that you can buy. For example you can buy regular 3/4" heim joints for $10-$15 ea or you can pay $30-$45 ea for moly heim joints - there is a difference, the regular heim joints will rattle soon after installation whereas the moly heim's won't.



I've avoided putting any names here on products because I do not want to be known as someone who talks products down to sell my own. Just wanted you guys to have a complete picture so you understand what you're looking at buying. I'm only posting my signature here to stay within the guidelines of the forums - if you want to blast me for this post go right ahead I understand and will take it like a man.

I can guarantee you that the distance between the front eye on the spring and the axle changes with travel. You can prove this out for yourself if you don't believe me. Take a tape measure and measure the distance between the front eyelit bolt and the centerline of the axle at the spring. Now either put a lot of weight in the truck, put a trailer on it, or put some weight in the bed of the truck on one side and use a jack to lift that side tire as high as you can - then measure the distance. I guarantee it will be longer. If the front section of the spring was truly fixed as you say then there would be no need for there to be springs there at all, they could make the rear suspension cheaper by putting solid rods that pivot at the front and are solid at the axle and only have the springs from the axle to the rear shackle.

 

[curatchko]

The axle does 'not' move on the spring. The axle perch is 'fixed' on a perch locator pressed in the spring pack. These 2 points, being the Eye, and the Perch Locator are fixed. So 'technically' the axle is in a fixed location to the front eye, with the Master leaf. The master leaf is essentially a 'bar' in the front half. The location of the axle can only move forward, or backward due to 3 things. Spring 'wrap', Bushing deflection, and or the arc created by the pivot point, which is the front spring eye.



Eliminating the spring wrap, with a bar that pivots on the spring pivot, should not create bind because the rear half of the spring is floating. What could it possibly bind against? There is nothing to bind in the rear half... . floating.



The only thing that should cause the front half to wrap, is the axles desire to rotate the opposite direction of the drive wheels, and the springs inability to control this motion, until a certain point is reached, at which point the spring unwraps, and this happens over and over...





I appreciate your input and thanks for the information you provided.

 

[Steve St.Laurent]

No, the axle doesn't move on the spring, but the spring flattens as the suspension compresses. That is the reason for the shackle at the rear. Let's take a piece of string as an example. Lay it out straight and say it's 10 inches long. The distance from the end of the string (the spring eye) to the middle point (the axle) is 5 inches. Now make that string into a U shape and the straight line distance between those two points is now less than 5 inches. That's the same thing that's happening on your leaf springs. The front and rear part of the springs are the same material - there is nothing holding that front part rigidly in an arc shape. So when your suspension compresses the front section flattens the same amount as the rear section, the shackle is there to allow the distance between the two spring eyes to get longer so that the springs can function. Do me a favor and try what I said above - put a lot of weight in your truck, put a heavy trailer on or something - you will see that the spring flattens out on both sides of the axle.

 

[TPlasek]

Are you looking for bolt on trac bars or are you looking to build something. I have a jeep, with chevy 350, Dana 60's, 40" tires and LOTS of gear. I finaly made a setup from a $25 part from tractor supply and some steal I had laying around. It is VERY effective buts lots of work to install. Best thing is, it iliminates the axle wrap at the center pumkin and not in the tubes. I have seen way too many dana 60's and 14 bolts twist the tubes out of the center section when you try to eliminate axle wrap using the axle tubes.



Let me know if you are a welder or if you have a person to do the job for you and I can email you a picture of how I have mine setup. I can also say, I have done the math and seen it in action. It will not bind your suspension. (Lots of pictures to prove it!!!)

 

[curatchko]

I'd be curious to see what you have done with the Jeep. I can weld and fabricate myself.



I had originally planned to use heim joints and round tubing... I'm curious to see what you have done.



Send me pics at -- email address removed --

 

[JoeyD]

I would like to see you pics as well.

-- email address removed --

 

[BLACKRAM]

Steve's bars use very large heim joints and are tube stock. The ends of the tubes are tapered and threaded to give an exact fit.



The suspension DOES NOT bind, despite the arguments to the contrary. The ride is actually smoother, on or off road.

 

[Oxjockey]

curatchko, are you saying the axle always travels in a line, perpendicular to the frame? That's just not the case. As Steve says, when the spring is compressed, the spring flattens out and the axle moves towards the shackle mount. Thus elongating the distance between the centerline of the axle and the fixed mount.



Typical traction bars on Jeeps, etc, look like this:



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I'd rather see the shackle above the mounting point, at the same angle as the shackle in the rear, but...



And I'm about to make one for my CJ, as I'm in the same position as TPILaske. Lots of motor, spring over, and tall gearing. I'm not prepared to make a setup like this:



#ad




Avalanche sells the ring to go around a D60, and then has those side braces, but I'm happy with a bar to tube design.



Bryan