SOA too high; is it possible to flip leafs to lower some? (1 Viewer)

[cruiserrg]

In rems case his leaf springs don't handle locating the axle. He is using a floating leaf spring design where the leaf floats over the axle, those 1/8" staps facitilating the floating are going to hold anything.

Yes more speration is better (which I suggested in my first reply to rem if he is drag racing), just wanted to point out that it can be done. I also pointed out that it really depends on the strength of the materials involved to handle the stress.

Were the failures you noted due to any other stress involved like a kink in a lower link due to rockrash? The tearing you are describing sounds like a lower link bending (like laying down hard on a rock), or a hiem or bolt failure before said tearing of link tubing.

LOL Ugly tree stands rock!

 

[Mace]

large combination of things.

fundamental geometry, load psi, strain on the materials, etc...

Major and easy example is leverage, similar to standard rachet vs breaker bar. more seperation would be better.

Where do the strains increase? on the axle end??? so you are saing that an increase in the length of a link mount is less likely to rip itself from the axle
???

 

[cruiserrg]

Where do the strains increase? on the axle end??? so you are saing that an increase in the length of a link mount is less likely to rip itself from the axle
???

I drew a quick pic to in paint for illustration.

Basically the leverage is created by the distance (D1 and D2) from the axle center rotational point. The further the distance the links are from axle centerline the less force (F1 and F2) required to hold the axle in place to transfer the power to the ground.

The top pic shows traditional links, the bottom with lowers above center rotation.

Now I drew the up and typed quick and don't have my chassis books in front of me so I could have all wrong , and there are many other forces involved not pictured (equal opposing forces, and the angles of acting forces on the angles of links, etc...). I also don't know for certain if the force in the bottom pic is full rotation about the axle centerpoint or if some of it is split due to the axle trying to rotate about the upper link frame mounting point. Hard to say without testing, but changing the location of the lower link from below axle centerline to above does change the force effects on the lower link, amounts I am not certain of.

Discuss.

 

[Toyoland66]

How about this.......

https://forum.ih8mud.com/attachment.php?attachmentid=18161&stc=1
stress.GIF

I am rusty on Statics, but the forces on the bottom illustration will be at least double the ones on top

 

[Mace]

sit and chew on this one for while longer..

I'll give you a hint.. Where do the forces come from???

 

[Mace]

Reuben, you have the general forces correct.

Toyoland has it exactly backwards

The forces are created from the axle center by the tires. not from the link mounts. no matter what the orientation or the mounting points the forces seen by the link mounts where they mount to the axle remain the same (with similar traction and skinny pedal) the location of the links in relation to the axle centerline will only vary the force seen byt the links. Not the forces generated by the axle.


So I ask. Why can't 3" of vertical seperation sufficiently control axle wrap (given the links are strong enough to hold and the frame mounts are strong enough)

 

[HI^C]

they are both correct, well maybe not exactly double the force, lol

toys example top is less force over greater distance to move the weight x distance, where lower is more force less distance for the same distance x that the weight moved. simple leverage.

in looking at controling axle wrap only, and using a 4 link.

General terms yes, forces generated will be the same for same vehicle regardless of mounting, but the forces vary vehicle to vehicle. Can change per same vehicle just by changing air pressure or tire size, etc....

I finish my though a bit later.

 

[Toyoland66]

Ok.......Given two axles, with the same power applied and the same size tires in the same situation the rotational forces exerted in lbs/foot will be the same...right

So lets say just for example that there is 1000lbs/foot being applied in rotational force to the tire, and the tire is fixed and wont spin,

if the links are seperated by 3" then the forces exerted on the links will be 4000 lbs [(1000 lbs/foot) / (.25 ft)]

if the links are seperated by 6" then the forces on the links will be 2000lbs [(1000 lbs/foot) / (.5 ft)]

It is all about leverage, and the leverage changes based on the verticle seperation of the links at the axle, just like a 3" breaker bar will undo a nut with less force exerted when compared to say, a 10" ratchet.

The forces might look backwards to you because those are the reactant forces in that situation, if you are familiar with statics at all

Correct me if I am wrong, but only if you actually know what you are talking about

 

[Mace]

Ok.......Given two axles, with the same power applied and the same size tires in the same situation the rotational forces exerted in lbs/foot will be the same...right

So lets say just for example that there is 1000lbs/foot being applied in rotational force to the tire, and the tire is fixed and wont spin,

if the links are seperated by 3" then the forces exerted on the links will be 4000 lbs [(1000 lbs/foot) / (.25 ft)]

if the links are seperated by 6" then the forces on the links will be 2000lbs [(1000 lbs/foot) / (.5 ft)]

It is all about leverage, and the leverage changes based on the verticle seperation of the links at the axle, just like a 3" breaker bar will undo a nut with less force exerted when compared to say, a 10" ratchet.

The forces might look backwards to you because those are the reactant forces in that situation, if you are familiar with statics at all

Correct me if I am wrong, but only if you actually know what you are talking about

So, for controlling axle wrap.. How does the force on the weld at the axle change with a longer mount?


The correlation to a breaker bar is not valid when talking about the axle end.
It is valid when you are talking about the frame end (basically your hand at the end of a breaker bar).

A better correlation is comparing the socket on the end of the breaker bar. Think of two bolt heads that are absolutely identical. To get the bolt to fail using a 1' breaker bar you need some force X. To get the bolt to fail using a 5' breaker bar you need a significantly lower force. That being said, the force applied to the bolt head itself is the same in either circumstance.

So, forces that control axle wrap.
The only way to control axle wrap is to limit movement. That movement is caused by a force incured by the tiresish (there are DS forces but for this example let's forget them)

If your links can handle the forces involved (proper material selection and build style) then there is no reason that 3" of vertical seperation is any worse than 6" of vertical seperation.

The axle base mount see the same forces either way. Length does not change the forces on the axle end.

So I ask, what does vertical seperation have to do with axle wrap???

 

[Toyoland66]

You are right, the force on the weld securing the link to the axle doesn't change, but the forces on the links does, and that effects the link ends, the links themselves, the bolts securing the ends to their brackets, and the brackets themselves.

Here is a perfect illustration, thes are the exact same forces that would be on an axle trying to control wrap.

Tell me, which scenario would exert more force on the boulder

https://forum.ih8mud.com/attachment.php?attachmentid=18300&stc=1
boulder lever.GIF

You are correct to say that you could build a system to be reliable with a small amount of verticle seperation, but everything would have to be built stronger to reliably contain the extra force exerted

And having those forces in this case traveling into a link mount that is basically a lever on the frame......

And yeah, both setups will control axle wrap, but for how long, especially when in this case the components arent exactly very "heavy duty"

 

[Mace]

Toyo, I am not disagreeing with what you are saying.

All I am saying is that vertical seperation basically has nothing to do with axle wrap..

I am basically sick and tired of people making statements about vertical seperation and how you are gonna rip your axle mounts off if you do not have 12" when it is not true.

The less vertical seperation you have the more force the links/Frame mounts will see. But axle wrap is independant of that.

VS is a good idea for may other reasons than axle wrap. ANY stoutly built link suspension will control axle wrap as long as there is some seperation at the axle end.

 

[HI^C]

YEP< YEP< LOL LMAO

Both correct again,

base welds see the same, but it is this shorter vs longer mounts that affect both the force on the bolts links and frame mounts, that both affect the strain on materials and wear.

Breaker bar is vaild in correlation with the axle using the rotation as the centerline and the mounts as your hand. Exact math might be a bit more complicated then above but for simple example it works. Yes, you would have two points in this case per side.

"If your links can handle the forces involved (proper material selection and build style) then there is no reason that 3" of vertical seperation is any worse than 6" of vertical seperation."

You kind of already shown the major problems with using the small seperation at the axle, (propler material, build,) with these kind of forces you can wear or shear bolts, tube, elongate holes, kill hiems. AT a considerable amount faster and more expensive then going with a less load. Costs associated with those materials, extra time, high loads, etc... all make smaller seperation worse then greater seperation.

Again it will work with low force vehicles, "very little overall weight, low hp, small tire size etc.... might get away with 3" or less sep, but in no way would i ever suggest it or do it myself. And i will say i will be the first to laugh and leave your ass when it breaks, hard truth, LOL."

Axle wrap is that force (rotational force) how it is controlled is what we are discussing. it cannot be independent per say because without it this wont be a discussion, nor would we have to account for it.

Before we get to far, "tree stands" my wording, refers to the large gangly looking materials used for upper link mounts.

 

[HI^C]

Sorry above i was mid type and went and ate, then came back to finish it, LOL

BTW

where you seen this at??
" I am basically sick and tired of people making statements about vertical seperation and how you are gonna rip your axle mounts off if you do not have 12" when it is not true. "

 

[cruiserrg]

Before we get to far, "tree stands" my wording, refers to the large gangly looking materials used for upper link mounts.

Thanks for the clarification, I got the impression you weren't fond of full awn tube buggies. More details on what make upper link mounts "tree stands" in your terms. Design critique always welcome.

I'd like to hear the discussion of link seperation in terms of the picture I made above. If the distance from axle center of both setups is identical, what difference in the force is seen by the links that one would fail more than the other?

 

[HI^C]

still not really my cup of tea, but i did build about a 1/3 of a buggy. Rocks, 53s, 20 doublebeadlocks, 454 bbc, sm465, 203-205 doubler, full air bag suspension (caged),
it was like 24" travel at each tire. But it got scrapped, some parts are gone some i
am still getting rid of, some parts are installed in other rigs.

while the square tube does the job, it just looks rough and unfinished. hoops, gussets,
flat plates, etc...? need to do more then just be a tall square on a round rig. just my opinion.

I was holding back this setup, if axle seperation is the same with the above/below and the above/above they should react the same, direction of force on the links changes between the setups. Now this is assumeing that there is one axle mount per link, not two links to one axle mount.
Problem is where to fit 6-8" seperation completely above the axle centerline.

 

[Mace]

the VS gripe is a global one not just this thread.

Yes it is harder on links. But 3" of VS can stop axle wrap. I only have about 6" of VS in my rear links. And no wrap..