Suspension travel upgrades on an 80

[landtank]

Sumotoy, while the arc the axle might be the same after dropping the barcket the path travelled is different. Most rubbing occurs at full compression of the axle. Most will want the axle at that point to be in the center of the wheel well to try to avoid rubbing.

Leaving the arm attached at the frame acheives this (provided that Toyota designed it that way) because upon compression the axle moves forward to that center.

Dropping the rear bracket will cause the axle to begin moving rearward upon compression.

I'm not sure what real world effect this will have and tire size and bumpstop position would also influence the possibilty of rubbing.

I realise that the use of a drop bracket corrects caster in itself, I was refering to the actual process of correcting caster which is usually part of lifting a truck when not using drop brackets.

 

[SUMOTOY]

Sumotoy, while the arc the axle might be the same after dropping the barcket the path travelled is different. Most rubbing occurs at full compression of the axle. Most will want the axle at that point to be in the center of the wheel well to try to avoid rubbing.

Not addressing preference. I'm only addressing articulation up to interference or bind. "Avoiding rubbing" is defined as interference.

Leaving the arm attached at the frame acheives this (provided that Toyota designed it that way) because upon compression the axle moves forward to that center.

Dropping the rear bracket will cause the axle to begin moving rearward upon compression.

Right now, you have changed the rod angle. I haven't. I only addressed horizontal rods for now. If we agree that my pic in 118 is correct, I'd consider looking at angling the rod. I suspect the arcs again will zero with the givens. Let's not jump ahead LT. I don't disagree with you at all, in preference. In *geometry* there is some basic disagreement that needs to be sorted first?

I'm not sure what real world effect this will have and tire size and bumpstop position would also influence the possibilty of rubbing.

Interference, again I don't disagree yet. I could scale my drawing, if we want to use it as a reference. We aren't there yet.

I realise that the use of a drop bracket corrects caster in itself, I was refering to the actual process of correcting caster which is usually part of lifting a truck when not using drop brackets.

Ok, but the acceptable spec to Toyota stays at 3degrees +/- 1, which if we mathed that out is a pretty high variance, in fact more as we lift the truck. Wonder what would happen if you moved caster to the extreme of the stock spec, couldn't we indeed possibly still use the axle lift method?

More questions. I leave 118 alone until we have agreement that's correct as presented. Then maybe we can delete all previous, and start working thru preferences and specifications. I'm not willing to do that yet. I can scale the drawing, and manipulate it to reflect those preferences. But we can't seem to get agreement that's the right drawing.

Again, I'll say for now LT, I'm not disagreeing at all with you so far. Put another way, I completely understand your point. My drawing only references post 15 and 18 and the subsequent carnage for now. Pic in 118 *can* be used for further explorations.

Scott Justusson

 

[Walking Eagle]

Sumotoy, while the arc the axle might be the same after dropping the barcket the path travelled is different. Most rubbing occurs at full compression of the axle. Most will want the axle at that point to be in the center of the wheel well to try to avoid rubbing. .

YES! With Sumo on my ignore list I can't see what he's saying, but glad to see no one else is buying what he's selling either.

Course, I never did understand why he started throwing in articulation since I was only saying way back in the begining that the path for dropped frame brackets is not the same for raised axle brackets - aka - not the same effect.

 

[landtank]

I'm still unclear what you are refering to when you say rod length/axle rods.

Anyway you seem to be at the beginnings of your suspension design while most of us are done or well past that.

Myself I have a 4" lift with 3* of caster and I'm not using drop brackets. Suits me just fine.

It will be interesting what you come up with.

 

[ElJefe]

... Dropping the rear bracket will cause the axle to begin moving rearward upon compression.

The rearward travel of the axle is almost nil when talking about 3 inch brackets. Assuming a length of 33 inches from pivot to center of axle, compressing 3 inches past level only brings the axle rearward 0.2 inches fronm the level position.

 

[Walking Eagle]

I'm still unclear what you are refering to when you say rod length/axle rods.

Anyway you seem to be at the beginnings of your suspension design while most of us are done or well past that.

Myself I have a 4" lift with 3* of caster and I'm not using drop brackets. Suits me just fine.

It will be interesting what you come up with.

Actually, the funny thing is I don't plan on doing anything out of the ordnary. I have J's in the garage, and caster bushings. I have some L shocks I picked up used, but one of them is completely dead. I might go for some long travel shocks, and fab up some mounts, but nothing all that freaky. I'd love to do more, but these used parts just keep falling in my lap (thanks to my brother), and I can't pass up cheap and proven.

I might do ford shock towers on my 80 like I did on my 40 - it flexes pretty good considering it's low lift, and 14" travel shocks

 

[Walking Eagle]

one more just for fun....

 

[SUMOTOY]

I'm still unclear what you are refering to when you say rod length/axle rods.

You don't need to. All you need to know is that the rods follow the arc.

Anyway you seem to be at the beginnings of your suspension design while most of us are done or well past that.

With all due respect, most here have accepted the compromises with whatever they use. If we get agreement on HOW a suspension articulates, maybe some of those compromises could be understood, whether one correct for them or not.

Myself I have a 4" lift with 3* of caster and I'm not using drop brackets. Suits me just fine.

It will be interesting what you come up with.

Nay gives good argument for not using drop brackets. I'm only intrigued with the idea of the design. And trying to get a tech forum to agree on a baseline. Then anyone can come up with whatever they want. It can be plotted to see the potential geometry issues. Again, whether one chooses to fix them or not.

SJ

 

[SUMOTOY]

The rearward travel of the axle is almost nil when talking about 3 inch brackets. Assuming a length of 33 inches from pivot to center of axle, compressing 3 inches past level only brings the axle rearward 0.2 inches fronm the level position.

Agreed (I measured a 1/16 of an inch with my Stanley on a 42 inch rod example). The arcs are massively zoomed for path. In actuality, normal production tolerance of 3 +/- 1 of caster angle, really makes the arcs all but identical, depending on which specific truck does the mod. Then you have to determine whether you want to change that tolerance when you lift the truck. Add in production tolerances of arm length, bushing slop, axle bracket mounting tolerance, frame axle bracket mounting tolerance..... This whole exercise becomes moot in terms of arc differences. Use two axle rods during articulation, it's moot cuz the arcs sum equally.

SJ

 

[SUMOTOY]

YES! With Sumo on my ignore list I can't see what he's saying, but glad to see no one else is buying what he's selling either.

Course, I never did understand why he started throwing in articulation since I was only saying way back in the begining that the path for dropped frame brackets is not the same for raised axle brackets - aka - not the same effect.

See your pic 146 #1 or pic 147. It's the exact same effect. You can draw an arc on the left side of the truck showing the left axle rod. I only claim from your pictures that the other side of the truck draws the opposing arc. Drop the frame or raise the axle - aka, same effect.

Ignoring the reality of the same effect, doesn't mean it's not there.

Selling? Naw, just looking at post 15 and 18, and thinking something is indeed wrong. I just didn't use all caps, nor did I ignore articulation.

SJ

 

[landtank]

You don't need to. All you need to know is that the rods follow the arc.

thanks for the clarification.

If we get agreement on HOW a suspension articulates

Why must we all agree? You insist you know what's going on so let's see what you got. Put together a theorectical suspension setup and what parts you'd use to help us get a better idea of what you're thinking.

Then anyone can come up with whatever they want.

We're already doing this. While there are a few who run the same kits that are offered, some have mixed and matched there parts to get something that they feel will suit them better, whether its cost, ride quality of off road ability. And still others have designed their own stuff which is part of the fun also.

 

[landtank]

The rearward travel of the axle is almost nil when talking about 3 inch brackets. Assuming a length of 33 inches from pivot to center of axle, compressing 3 inches past level only brings the axle rearward 0.2 inches fronm the level position.

From my calculations with a 4" lift the axle will move .26" forward when the arms are compressed 4". I got the impression from all the previous posts that there was some focus on detail and I just wanted to be clear. I did follow that with a real world disclaimer.

 

[SUMOTOY]

thanks for the clarification.
Why must we all agree? You insist you know what's going on so let's see what you got. Put together a theorectical suspension setup and what parts you'd use to help us get a better idea of what you're thinking.

Well, I just did the axle rod arcs for a 3in lift with 3 in articulation using a 42 in rod length. One setup uses pivot frame drop, the other axle pivot lift. Parts? If dropping frame, that would be four plates with holes in them. If lifting the axle mounts, that would be four plates with holes in them. We must agree on how geometry applies to 2 axle rods during articulation. It just can't be that difficult on a rigid axle truck. I normally design suspensions and geometry for 6-8link independent suspensions with different axle designs front and rear. Why not agree that the drawing in 118 is correct, and move on?

Fear of agreement? I have none, I'd change it to be correct, but it appears to be, even WE is using it. I have a program that will allow me to do whatever story or theory we want to use. To properly use it as reference, needs agreement that the tool is valid. If none is made, that's fine with me, but the next step would require a LOT more time and effort to scale it and draw the ACTUAL numbers. I'm mildly interested at this point, WE put down a lot of carnage before post 118

We're already doing this. While there are a few who run the same kits that are offered, some have mixed and matched there parts to get something that they feel will suit them better, whether its cost, ride quality of off road ability. And still others have designed their own stuff which is part of the fun also.

No problem with that. As some sort of 80 tech FAQ, I was actually thinking we could plot out any and all options with only a few pieces of data. I can make a program that allows for any creativity with very few pieces of information inputed. Show and measure only the changes, the rest is already given. Then we can maybe put objective numbers to show exactly what's happening in the subjective 'feel'.

That would just be the curious nerd in me on a tech forum. I sometimes forget that geometry on a forum can be controversial, subjective, and reach different conclusions using the same data. I personally find that strange, but I'm learning to understand it's the nature of a forum too.

Scott Justusson

 

[Walking Eagle]

See your pic 146 #1 or pic 147. It's the exact same effect. You can draw an arc on the left side of the truck showing the left axle rod. I only claim from your pictures that the other side of the truck draws the opposing arc. Drop the frame or raise the axle - aka, same effect.

Ignoring the reality of the same effect, doesn't mean it's not there.

Selling? Naw, just looking at post 15 and 18, and thinking something is indeed wrong. I just didn't use all caps, nor did I ignore articulation.

SJ

Just had to check back.

I'm really currious where the axle rod is on my leaf sprung 40.

Also really currious were you're seeing all caps in post 15 and 18.

 

[Walking Eagle]

It just can't be that difficult on a rigid axle truck. I normally design suspensions and geometry for 6-8link independent suspensions with different axle designs front and rear. Why not agree that the drawing in 118 is correct, and move on?

I don't know why I can't just leave this alone - what suspension have you ever designed? I'm not buying it. Just cause you claim to be an audi mechanic and have put some coil overs on some A4's, does not mean you've designed suspensions.

Fear of agreement? I have none, I'd change it to be correct, but it appears to be, even WE is using it. I have a program that will allow me to do whatever story or theory we want to use. To properly use it as reference, needs agreement that the tool is valid. If none is made, that's fine with me, but the next step would require a LOT more time and effort to scale it and draw the ACTUAL numbers. I'm mildly interested at this point, WE put down a lot of carnage before post 118

You can call me by Heath or Walking Eagle, and stop the WE bull. It doesn't take that long to put in real #'s if you're working with a CAD system - which it doesn't seem you are.

No problem with that. As some sort of 80 tech FAQ, I was actually thinking we could plot out any and all options with only a few pieces of data. I can make a program that allows for any creativity with very few pieces of information inputed. Show and measure only the changes, the rest is already given. Then we can maybe put objective numbers to show exactly what's happening in the subjective 'feel'.

That would just be the curious nerd in me on a tech forum. I sometimes forget that geometry on a forum can be controversial, subjective, and reach different conclusions using the same data. I personally find that strange, but I'm learning to understand it's the nature of a forum too.

Scott Justusson

Hummm... the geometry I showed using a real CAD package, is not subjective. You make it controversial and reach your own conclusions cause you're not looking at the right thing. And we're not talking about articulation at all, never were when comparing droped bracket scenerios. The simple truth is all the rest of us were discussing is how different mounting of the radius arm on each end can and will change the axle's path relative to the rest of the frame. For this, we don't need to consider the passenger's side, or even consider that the vehicle has 3 dimensions. All we're talking about is the axles movement up and down and forward and backwards, and it doesn't matter what the other side of the car is doing at all!!!!

Go find a picture online of a 6" lift without slee's or someone elses extended arms. Then look at a picture of Yellowchao's or someone elses 6" lifted with drop brackets. The axle sits noticeably back. Could that be why slee's kit includes longer arms to put the axle further front again? (in addition to the caster correction obviously). If it's not starting in the same place, it can't take the same path. And since the arms hit bumpstops at the same place (2" lower than stock), the angle at that point isn't the same, so they're not going to be in the same location either. I don't think anyone here will disagree with that (except maybe you). If they don't start in the same location, and don't end in the same location, they don't follow the same path!!

To get back to the origional statements in 15 and 18. Raising the brackets on the axle just gives you a different shaped arm. The arm can be a curve, a L, or a straight line - but the path of the axle is always going to be a radius centered at the mounting of the radius arm. And if the centers of two arcs are not at the same place, they will not make the same path.

Where is your problem with understanding this? I mean come on, in the air bag over coil thread you said the VW Touraug (sp) wasn't IFS, and that the toe in on an 80 series was going to change throughout suspension travel. If you can't get that much right, I certainly am not going to trust you.

 

[landtank]

We must agree on how geometry applies to 2 axle rods during articulation. It just can't be that difficult on a rigid axle truck.

First, we don't have to agree, go do your thing.

Second, since you won't explain what an axle rod is to me, nothing you are writing makes any sense.

Third, I won't agree to anything I don't understand. You might be used to having people blindly agreeing with you but that's not me.

 

[SUMOTOY]

WE
I'm curious how 59 and 66 differ. They shouldn't

I'm curious how my drawing 118 is "wrong". You even used it. I'm curious how your CAD got picture 101, it doesn't reflect the proper axle mount or arcs (specifically it's missing lift axle pivot).

I'm curious how your cardboard only addresses a single rod on a dual rod articulating axle. I'm curious how your cardboard arcs don't intersect properly to reflect axle lift.

I'm a curious guy by nature. I can handle you being pissed off.

I don't think you have much of this right, nor are your posts consistent. To help educate a "clueless" guy like me, you can:
* make your posts consistent (and continue to delete the others)
* correct my geometry and conclusions in 118
* reread the givens in the story problem to see my posts as
consistent
* Use Cad to 'fix' 118 *and* come to a different conclusion
regarding articulation arcs of 2 static level axle rods. That should
also disprove my articulation arc formula in the lower right

There's a lot of folks watching this thread. It might be nice to get it cleared up? Since you keep wanting to 'add' to 118, not claim it's wrong, why don't we start there?

Thanks for your continued efforts on behalf of this ascribed clueless

Scott Justusson

 

[SUMOTOY]

First, we don't have to agree, go do your thing.

Second, since you won't explain what an axle rod is to me, nothing you are writing makes any sense.

Axle rod = the 2 rods found underneath an 80 to locate the front axle. Their front pivot point is found attached to the axle underneath. The rear pivot point is found just about at the back of the front door on both frame rails.

The arc of these rods goes up and down with the respective side of the axle during articulation. Since it's geometry LT, I should rephrase: There shouldn't be any *disagreement*

HTH

SJ

 

[landtank]

So your talking about these then. It would go a long way for all of us if you would take a little time and learn/use the proper terminology as it applies to the Land Cruisers.

So you are talking about long arms then when working up some changes.

 

[Walking Eagle]

Axle rod = the 2 rods found underneath an 80 to locate the front axle. Their front pivot point is found attached to the axle underneath. The rear pivot point is found just about at the back of the front door on both frame rails.

hummm... they don't pivot anywhere but at the frame. They twist a little in the bushings, and so does the axle, but they certainly don't pivot under the axle.