The Wishbone MIGHT work! lotza PICS

[Beezil]

mark, i think he means the action that comes from "axle steer"......

if that's what he meant I'm catching his drift....axle steer should be very minimal considering the length of the lower links, and the fact that they are only like 15-degrees angled at static height, so the operating arc difference are somewhat tame during cross-up.

I'll keep an eye on it though.

 

[C-ROK]

It was the axle steer I was refering to.

I thought about it a little more and I think you're probably right Beez. With the length of the arms and the slight inward angle, your drop steer misalignment should be pretty small.

It would be pretty easy to estimate on some graph paper. You could get an estimate of the degree of mislaignment and then simply check it on the bushing by hand.
I can guarantee the bushing isn't going to restrict any articulation. Worst case, you may consume some bushings over time.

My front radius arms use poly bushings at the axle end and I go through about a set of bushings a year due to the differing caster rotation that each arm imposes during articulation.

 

[Economos]

Wow... yeah.

 

[satan]

Hey, why not run your polu bushing on a vertical pin -- it articulates already for roll - running it vertical will allow massive (granted a bit off-center) steer (yaw) ---

Or am I 'late to the show' and that's been your plan all along?

 

[XJJPR]

It was the axle steer I was refering to.

I thought about it a little more and I think you're probably right Beez. With the length of the arms and the slight inward angle, your drop steer misalignment should be pretty small.

It would be pretty easy to estimate on some graph paper. You could get an estimate of the degree of mislaignment and then simply check it on the bushing by hand.
I can guarantee the bushing isn't going to restrict any articulation. Worst case, you may consume some bushings over time.

My front radius arms use poly bushings at the axle end and I go through about a set of bushings a year due to the differing caster rotation that each arm imposes during articulation.

Ok

I was thinking that would be minimal also, poly should be fine for that, that is why I thought you missed the bearing joint.

mark
orgs mfg

 

[Beezil]

Hey, why not run your polu bushing on a vertical pin -- it articulates already for roll - running it vertical will allow massive (granted a bit off-center) steer (yaw) ---

and then you loose your ability to swivel about the vertical travel of the axle up and down.....more movement to worry about than the minimal axle steer. I should be okay.

 

[Blix]

There is some validity to your parabolic theory, but from what I remember it has to be a near-perfect parabola. Either way, it doesn't matter much because that is pretty much the shape you had to take to get around the pan. If you are worried that your Wishbone will fold with some extreme cornering, you might be able to weld in a curved strut from half to half that would curve right underneath the oil pan at full jounce. It would probably be one hell of an arc, but it should be strong enough to keep the wishbone tied together.

-Steve

 

[88justin]

On that note, during cornering, the stress concentrations in the wishbone are at the bushings where they connect to the parabola, and along the inside edge of the parabola. you might consider taking some measurements and seeing if some small gussets might fit near the heims, or the Poly bushing. Of course,you could also sleeve some portions of the parabola. I do like Blix's idea, but that may have to be an awkward shape.

Looks good!

 

[88justin]

i guess gussets wouldnt really fit at the heim ends, maby a sleeve would work in that location.

 

[MaXJohnson]

For the sake of discussion, I would think that the strength of the parabola would relative to force in direction "A" in the picture, not "B" where it is needed. Even considering "A", the strength is in the upper portion of the parabola, truncated by the horizontal yellow line and this assumes the legs are constrained where the yellow line dissects the arch.

The ideal shape would be the yellow triangle. At 45°, the arms take the full load of lateral forces in compression and tension of the arms. This triangle would be weakened by the use of curved arms which would not handle the compressive force nearly as well as a straight tube.

For a more acute triangle, as indicated in purple, less of the load is handled by the arms in compression and tension. The difference is handled by the beam strength of the arms.

A partial solution would be to widen the base of the triangle by moving the rear mounting points further apart. IIRC, this is what OneTon did by using the LCA mounts for his upper wishbone.

 

[Beezil]

I cannot widen the arms....

that shape represents the most efficient shape that fits in that MOST confined space!

I contend that the parabola is stonger than if I did a "U" arm with a constant radius. Since I have the ability to fabricate multi-radius forms, I went with the parabola shape. I tried like hell to fit a triangle, and there's no question that is the strongest form.

 

[88justin]

I think that you have some nice points there, i like the picture!

The more accute triangle would still have side tubes in tension and compression, just the forces would be greater. At the same time, less force in the direction of B vector would go into the mounts.

nevertheless, the apparent shortcommings of the parabola geometry can be overcomed by the strength of the construction material. If this particular design is too compliant and feels loose in the lateral direction, use a stronger tube. common sense.

adding some flat plates on the outsides and insides of hte parabola would increase its resistance to bending laterally. Im thinking somethingk like some 3/16" X 1.5" X the length of the curve. Square material is ideal for bending loading conditions.


enough said. This suspension is PIMP

 

[XJguy]

nice work

gawd I hope not! can't check articulation clearance at this point!

That has been my concern in trying to figure out a way to do what youre doing Beez.

Great work by they way.

XJguy

 

[XJguy]

Beez, how about triangulating the lower arms. Have them converge to the center at the body end. I dont know if this would actually fit but if it did, you then have 100% assurance you will not have any axle centering problems and you will not rely soley on the UCA for it. And if you decide to attatch it by one rod end, it will be one less to worry about loosening.

XJguy

 

[Scott Mac]

I cannot widen the arms....

that shape represents the most efficient shape that fits in that MOST confined space!

I contend that the parabola is stonger than if I did a "U" arm with a constant radius. Since I have the ability to fabricate multi-radius forms, I went with the parabola shape. I tried like hell to fit a triangle, and there's no question that is the strongest form.

Your research tells you that that shape is the most efficient shape that fits in the space you have available.

I think Alyn is trying to tell you that that shape is only efficient when the forces are moving from the point to the base. Not from side to side.

Spank me if I'm wrong.:moon:

Looks sweet. Paint it bright yellow so we can all see it work.

 

[magoo117]

How about some pics of the joint.What bearings did you use?You said your wishbone is 36",what is the length of your lower arms?sould they be the same length?I have Clayton's setup on mine now and I want to get rid of the tracbar,this looks like the deal for me.

 

[Beezil]

Beez, how about triangulating the lower arms. Have them converge to the center at the body end

I tired to do a double triangulated link design for the front using straight arms.....

YOU CAN'T.

not without some serious trade-offs namely, clearancing everything else that needs to be there....

driveshaft
exhaust
oilpan
motorstarter
bellhousing
transmission
fuel lines-brakelines (become an issue when having to keep them opposed from wherever the exhaust needs to go)

if any of you are confused by any of this, get on your creeper and crawl under your rigs, and you'll be able to understand how very limited you are in running links differently.

I am not saying the parabola is some magically strong shape. OF COURSE TRIANGLES ARE STRONGER! but the parabola is certiainly stronger than a "wishbone" with 90-degree/6" centerline radius bends going to the center joint, which has a very confined stress area, which I might add, will hit the top of the differential housing, whereas the parabola clears the diff housing too, and has about 2-3 inches more travle before it hits the area right where the pinion seal is.

the parabola is the most efficient shape fitment wise
it is stronger than a "U" arm
I was actually able to MAKE the shape I needed, no compromises fabrication-wise.

I enjoy critique, so fire at me!

 

[MaXJohnson]

Beezil, I'm not suggesting you change the shape. I think you picked the right shape. OneTon and Matt both went with a square with rounded corners. You parabola is superior to that and it's obvious that a pure triangle wouldn't fit. I'm just looking at ways you could optimize your shape. A broader base is one way to lessen the strain on the tube members. A shorter triangle, from the base to the swivel would be another(moving the rear mounts forward). This would require considerations in the side view.

Adding material strength and weight will offset the problems with design shape. Matt had problems with his lower arms and the axle joint of the upper, but I haven't heard of his or OneTons upper arms bending or failing. Your's looks to be the best of the bunch.

 

[Beezil]

Max, I know, you didn't have to explain at all, I LIVE for debate and open critique..... Yeah, there are one or two ways I could strengthen the shape, and if I could do it by changing proportions or length, I would have, but dammit, there are limitations and constraints everywheere!!!! arghhh!

I may be able to bridge the joint area with a web, we'll see.

the project is not finished because I am awaiting delivery of a steering ram I've been waiting 10 weeks to get...I'll have to seehow much room I have left over after it is installed.

until then, I am working on the rear now, which I have some preliminary pics of...I am leaving for the shop right after I'm done with this coffee, and I'll be metal-bitchin' all day...

magoo here's the joint....4130/or40 body, machined from solid stock to accept a pair of identical timken tapered roller bearings.

the shaft is 8620 alloy steel, with a fine thread cut into it to accept a top-locking nut, tightening adjusts the preload on the bearings. the joint is serviceable.

I forget the specs on the bearing in terms of trust and radial loads, but I remember thinking they were adequate.

 

[Chark]

Nice work Beez.....I just can't believe the amount of BS on everyone's opinion of "what you could of done". I realize what's real world and like you....can now only try the damn thing!!! Again, nice work and in my opinion..."It will work".