Suspension travel upgrades on an 80

[Hayes]

Not sure. I don't think so, but a single axle rod to the axle, isn't on our 80's. I'm a practical applications guy. I can look at a single axle rod and think we only have half the equation when we start to actually drive what we designed. The combined arcs of the axle rods exactly zero out any measured differences. If one rod follows the "shorter" path arc in lift, the other rod will follow the "longer" path arc in drop, by definition. And vice versa. Since the rod length is identical, and the rods were both statically horizontal, the differences in the arcs is exactly the opposite up vs down.

Therefore under articulation the arcs of the two axle rods on the same axle, zero out in drop frame pivot vs axle lift pivot mounting up to interference/bind.

I haven't done a drawing using a angled rod, since that wasn't a given.

Heath did a great job of cutting this all out. But that's only 1 dimension of two opposing and equal rod arcs. A guy like me looks at a live axle and says: "sure, now what's the other axle rod doing?" On a live axle, the exact opposite in fact.

SJ

But the front axle isn't ALWAYS articulated when when the springs are compressed: What if you're perpendicular to the obstacle--a speed bump, whoop-de-do, or any bump that you approach head-on? Wouldn't both ends of the axle and both radius arms follow the same path--essentially behave like one radius arm illustrated by WE?

Or is this NOT what you guys are concerned about anyway?

Hayes

P.S. I sort of understand your one side up one side down cancellation thing, but I ultimately don't understand the underlying issue or point of the whole debate. Thanks for answering the questions of the clueless.

Hayes

 

[SUMOTOY]

But the front axle isn't ALWAYS articulated when when the springs are compressed: What if you're perpendicular to the obstacle--a speed bump, whoop-de-do, or any bump that you approach head-on? Wouldn't both ends of the axle and both radius arms follow the same path--essentially behave like one radius arm illustrated by WE?

Paragraph 6 post 110. That's not the reality of vehicle dynamics. If a car is moving the front axle is ALWAYS articulated, springs compressing or rebounding. It IS an exception, but not accepted as one. Lots of completely stock production cars that can't accomplish dual compression without interference.

Or is this NOT what you guys are concerned about anyway?
Hayes

I design and build suspensions as part of my job. For a rigid axle, articulation and clearance is the key, and really was the discussion on the thread as a whole. Lift, drop, arcs, springs, etc all have to do with the dynamics of articulation.

P.S. I sort of understand your one side up one side down cancellation thing, but I ultimately don't understand the underlying issue or point of the whole debate. Thanks for answering the questions of the clueless.
Hayes

I've been so charged here myself Hayes... I think it's important to get some of the basic geometry of a live axle suspension agreed on. I was actually watching Nay's post (#2) which made a whole lot of sense in terms of clearance vs lift and pivot. As I haven't worked on live axle stuff for some years, that single thought was intriguing to me.

As for now, my own plan is to have limited adjustable suspension with airbags inside stock springs. Nay's thoughts on raising axle pivot got me to pull out the old design books that had live axle in them, and work it thru with a couple of drawings on visio. It pretty much confirms his thoughts and conclusions IMO.

Increasing clearance without increasing ride height has merit. And specific to the 80, can actually improve some of the known suspension geometry for better ride quality to boot. I only see good things from detailed exploration of lift axle mount application. Slowed a bit by some geometry disagreement doesn't seem to slow the views of the topic any.

Maybe it has value to others too.

SJ

 

[Walking Eagle]

Well, hell. I wrote this in another thread. Might as well mix this one up completely and post the link here. No way we can confuse this thread more that what it is.

https://forum.ih8mud.com/showpost.php?p=1035651&postcount=27

That's why I was currious if he was going to use something other than just adapters.

 

[frankies off road]

That's why I was currious if he was going to use something other than just adapters.

I looked threw that thread and i see nowhere that we where looking for more or less travel than the factory ome setup runnig 33" tires ,I did see where we wonted a 2.5" kit that will use 35" tires and maximize all the travel avalable,We did free up down travel over the factory OME kit by changing shocks and mounts.
The front OME shocks are double stud and that design binds the shock upon travel every little bit of free moovement helps.
The front sway bar did limit travel about 1.5" of travel.
And OME shocks are lesser shocks to the avlable alternative IMHO
Or Did I miss something ?

 

[sleeoffroad]

I looked threw that thread and i see nowhere that we where looking for more or less travel than the factory ome setup runnig 33" tires ,I did see where we wonted a 2.5" kit that will use 35" tires and maximize all the travel avalable,

I just don't see how you will maximize all the travel if you have to bumpstop it to avoid overcompressing the shock.

We did free up down travel over the factory OME kit by changing shocks and mounts.

factory oem or OME?

The front OME shocks are double stud and that design binds the shock upon travel every little bit of free moovement helps.

At what point does that happen? Only when the shock mount is twisted so much that the pin will touch the side of the mount. The OME bushings allow for plenty of movement..

The front sway bar did limit travel about 1.5" of travel.

This might be the case on forklift/ ramp testing but on the trail you can still force the suspension to go to full droop with the swaybar on.

And OME shocks are lesser shocks to the avlable alternative IMHO

I will agree with you that there are probably better shocks out there, but at what price. For the price, the OME shocks have pretty good features.

I am not saying there is anything wrong with the goals. I just don't see the solution.

 

[Walking Eagle]

WalkingEagle, just let it go.

Ya', I give up..... I think Sumotoy will be much more enjoyable on my ignore list.

 

[SUMOTOY]

Cardboard vs digital art

post 118 pretty much draws out more accurately your cardboard scenario. It differs only in that it presents articulation in both frame axle rod drop and axle rod lift on both sides of a rigid axle.

Happy to correct 118 if anyone feels it's in error. It should have corrected a few of the mistakes in the cardboard scenario. The axle pivot centerline crossover is too low, and it doesn't reflect articulation of 2 axle rods working on the same axle.

I'd still agree with Nay in post #2. Axle pivot lift should be considered a viable option to frame axle drop on an 80.

Thanks for sticking it out for a while Heath. It was interesting, maybe not all together productive.

SJ

 

[frankies off road]

Q... I just don't see how you will maximize all the travel if you have to bumpstop it to avoid overcompressing the shock.


F.O.R ANSWER,,,,,,We are maxamizing all we can with what we have left after the BUMP STOPS.

Q...... factory oem or OME?

F.O.R ANSWER,,,,,old man emu


Q..... At what point does that happen? Only when the shock mount is twisted so much that the pin will touch the side of the mount. The OME bushings allow for plenty of movement..

F.O.R ANSWER,,,,,, It hapend pretty quick from a resistance stand point, We need to make the front flow as free as posible,because the rear travels much easier than the front.every little bit helps front to rear sus BALANCE.


Q....This might be the case on forklift/ ramp testing but on the trail you can still force the suspension to go to full droop with the swaybar on.

F.O.R ANSWER,,,,,Yes thats correct but at the sacrafice of suspension balance, what amount ? but if it does not matter then why lift them at all..

Q.....will agree with you that there are probably better shocks out there, but at what price. For the price, the OME shocks have pretty good features.

F.O.R ANSWER.... I will let the users make that decision..

 

[Walking Eagle]

If anyone other than Sumotoy is interested

his own pictures show the different path a axle will take with droped frame mounts vs. stock

 

[T Y L E R]

Please do not adjust your brain .. we might be experiencing technical difficulties

 

[frankies off road]

If I can hand build these ,Dont ya think i could make a suspension kit work?

 

[Hayes]

At the very least, this has been a stimulating conversation, but I probably should have just continued to lurk silently in the background.

I'm no engineer. I've never designed anything automtive. But I've got a mostly functional brain (brain function is directly proportional to coffee volume), and I don't think that the geometry of the 80 front end is that complicated.

Thanks for addressing my comments, Sumo. I sincerely appreciate the effort. Unfortuantely, I still fail to see your side of the "same/different arc debate." After a night of sleep and a cup of java, I've concluded that the "one side up, one side down, cancelled arc thing" makes no sense to me. Square peg, round hole, as far as my comprehension goes. I can't see where Walking Eagle's explanation is wrong.

Again, no offense intended. Just keeping with the explicit nature of this thread .


Ryan Hayes

post 118 pretty much draws out more accurately your cardboard scenario. It differs only in that it presents articulation in both frame axle rod drop and axle rod lift on both sides of a rigid axle.

Happy to correct 118 if anyone feels it's in error. It should have corrected a few of the mistakes in the cardboard scenario. The axle pivot centerline crossover is too low, and it doesn't reflect articulation of 2 axle rods working on the same axle.

I'd still agree with Nay in post #2. Axle pivot lift should be considered a viable option to frame axle drop on an 80.

Thanks for sticking it out for a while Heath. It was interesting, maybe not all together productive.

SJ

 

[landtank]

I don't think that the geometry of the 80 front end is that complicated.

Actually it's not, but manipulating it for a desired result can be rather challenging.

 

[sleeoffroad]

If I can hand build these ,Dont ya think i could make a suspension kit work?

Frankie, I want to address this first. I am not doubting anyones capabilities. I was postings facts and measurements. There is a big difference between a total custom design and working within the limits of the 80 series stock setup. Not that you can not do it, but there are no free lunches.

Have you ever wheeled a loaded 80 with limited uptravel and big tires, with huge bumpstops to stop the tires from rubbing? These trucks are not buggies or rock crawlers. They need the up travel. Otherwiser you are on the bumpstops all the time. Not fun.

I can ask the same question. If we have the skillset at work to make a 80 do this, don't you think we can design a suspension?

This is not a pissing match. Just a thread about making the most of a 80 suspension.

Q... I just don't see how you will maximize all the travel if you have to bumpstop it to avoid overcompressing the shock.

F.O.R ANSWER,,,,,,We are maxamizing all we can with what we have left after the BUMP STOPS.

So what size bumpstop are you running on the truck that you are showing lifted on the forklift? Also are the rear tires touching or not?

Q...... factory oem or OME?

F.O.R ANSWER,,,,,old man emu

Ok, so you made it droop out a lot, with limited up travel. What happens when you drive this truck fast over bumpy roads? Will the uptravel be enough to not hit the bumpstops?

Q..... At what point does that happen? Only when the shock mount is twisted so much that the pin will touch the side of the mount. The OME bushings allow for plenty of movement..

F.O.R ANSWER,,,,,, It hapend pretty quick from a resistance stand point, We need to make the front flow as free as posible,because the rear travels much easier than the front.every little bit helps front to rear sus BALANCE.

I would venture to say the resistance the front control arms to twist is way more than the resistance on the shock. The front shocks are hardly at an angle at the top, yes they have a little angle at the bottom. But is that resistance worth going to a shock converter and using a shock with a bushing that is way smaller than OME? What about the durability of the smaller bushing on high speed travel on dirt roads? The bushing size is one of the great features of OME.

Q....This might be the case on forklift/ ramp testing but on the trail you can still force the suspension to go to full droop with the swaybar on.

F.O.R ANSWER,,,,,Yes thats correct but at the sacrafice of suspension balance, what amount ? but if it does not matter then why lift them at all..

The inbalance in a 80 suspension is due to the different designs of the links. There are tons of threads on here where people have tried, experimented, tested etc to get the front end to move. The only real fix is three or four link front.

Q.....will agree with you that there are probably better shocks out there, but at what price. For the price, the OME shocks have pretty good features.

F.O.R ANSWER.... I will let the users make that decision..

True, the customers can decide, but they should be given all the facts. The OME is already a 10" /11" travel shock. Installing a longer shock with shock adapters will make it droop out more. That is not the question.

I am questioning why does fitting this stock allow you to run 35's with 2.5" of lift better than a regular OME shock fitted with 2.5" of lift? That is what you are saying. Just because you are increasing droop does not mean the tires fit better.

When you run taller lifts, you move the axle articulation away from the frame. The wheelwell is still the same size, so compressing the tire up into the wheelwell causes the same rubbing issues as before but the plane around which the artciculation happens is further away from the body. What does this mean? We get more up travel which is what these trucks need.

You can get away with very little up travel in buggies etc, but not on these trucks.

I am not attacking you, just sharing knowledge that we have gained over the years.

 

[SUMOTOY]

his own pictures show the different path a axle will take with droped frame mounts vs. stock

Problem, there are 2 axle rods. The difference you indicate is equal. See the what if scenarios on the bottom right. If you say the axle rod right and axle rod left both go up in the same arc, that is NOT the definition of articulation plain and simple, that's climbing a speed bump. About 18in later, both axle rod arcs will go down on the same arc too. I suspect, if you want to argue 3in of compression on that speed bump, 18 inches later, we may not have tire contact yet.

This isn't hard nor technical. Heath try to define articulation first, it might help. Apply your drawing or art to a picture of an articulating axle on a truck. By definition in all your presentations to date, you have only done that to one side. My drawing shows both axle rods during articulation. I believe that's what we are speaking to in this thread.

WE, I appreciate you adding more dimensions to *my* drawing. That's not 'correction', that's agreement. The drawing then appears correct? Which then appears to directly conflict with all your drawings and your cardboard art.

Nay also made a good point that the amount of zeroed arc difference in 3in of articulation is minimal (on a 42 in rod ~1/16in). I'd further present that difference can be found measuring any two production 80's, with a 3degree +/- 1 factory caster spec (I won't draw that for now).

I was looking to present and find agreement on lift vs articulation vs pivot point of a live axle with 2 axle rods. Like found on the 80 we all drive here...

WE, when you put "WRONG" in all caps on any forum, you leave yourself open to challenge and correction. You can get mad and confrontational, that doesn't make your statement or presentation any more true. If you agree that my drawing is correct, then your drawings either have to support it, or they are specifically not correct.

Pleae feel free to add more dimensions to my drawing, or even scale it.


SJ

 

[landtank]

I'm not sure why we are focusing on articulation as it relates to the axle's arc it travels. To date I'm only aware of a single caster solution that maintains the axle's position on the arms. All others shorten the distance of the axle's position to the frame bracket.

Now some might jump on this to mention that drop brackets don't change that distance which they are correct but as WE has demonstrated the new path that the axle travels will result in a similar situation on compression.

 

[SUMOTOY]

Pic on Post 131 vs 118

Thanks for addressing my comments, Sumo. I sincerely appreciate the effort. Unfortuantely, I still fail to see your side of the "same/different arc debate." After a night of sleep and a cup of java, I've concluded that the "one side up, one side down, cancelled arc thing" makes no sense to me. Square peg, round hole, as far as my comprehension goes. I can't see where Walking Eagle's explanation is wrong.

Again, no offense intended. Just keeping with the explicit nature of this thread .


Ryan Hayes

Maybe this will help Ryan. Take a look at the articulation in Frankies pic on 131. One side of the axle is up, the other down. One axle rod will be traveling up, the other down. It matters not which mounting you use to do that, frame drop or axle lift. Let's assume (sorry Frankie, I know it's more) this is a 3in lift, copy the pic, so one has a 3in axle rod frame pivot drop, the other has a 3in axle lift pivot.

If Frankie used a frame pivot drop to change the rod angle in pic 131 (Black Axle rod arcs in the drawing), the upside (left) wheel would have the shorter arc (= arc C in the drawing). The Downside wheel (right) has the longer arc (= arc D in the drawing) Look at it from the side, That's my drawing, up to interference or bind.

If Frankie used a axle lift mounting pivot (Green axle rod arcs in the drawing) in the same pic 131, the upside (left) wheel would have the longer arc (= arc A in the drawing). The downside wheel (right) would have the shorter arc (= arc B in the drawing). Look at it from the side, that's my drawing, up to interference or bind.

To put Frankies machine on top of the hood of that ford can be done using frame drop pivot or axle lift mounting. The resulting picture is identical in either scenario. Then the combined arcs in both scenarios are also identical by definition.

ARC A (left) + ARC B (right) = ARC C (left) + ARC D (right)

If you look at *any* of WE drawings or cardboard art, you are looking at one wheel (axle rod) travel from the side. You can't pic the upside wheel (axle rod) travel only, because on a articlulating rigid axle one arc dictates the travel of the downside wheel (axle rod) arc. And vice versa.

Better?

Thanks for the pic Frankie, I like that one!

Scott Justusson

 

[SUMOTOY]

I'm not sure why we are focusing on articulation as it relates to the axle's arc it travels. To date I'm only aware of a single caster solution that maintains the axle's position on the arms. All others shorten the distance of the axle's position to the frame bracket.

Dropping the bracke or raising the axle mount is correcting caster, LT. You are putting a 42 in rod back to level, so the arc it travels equals the arc it travelled before lift.

Now some might jump on this to mention that drop brackets don't change that distance which they are correct but as WE has demonstrated the new path that the axle travels will result in a similar situation on compression.

What's the other rod doing on compression? If it's "articulating" that means it travels the opposing arc. Again, level the rods (key word in articulation is that there are 2), the combined travel of the two rods arc is the same.

This is not complicated. If we use the horizontal axle rod as a starting point and constant horizontal thru lift using two caster correction methods, the combined arcs are equal during articulation. WE only showed 1 axle rod arc on a 2 axle rod truck.

SJ

 

[frankies off road]

Frankie, I want to address this first. I am not doubting anyones capabilities. I was postings facts and measurements. There is a big difference between a total custom design and working within the limits of the 80 series stock setup. Not that you can not do it, but there are no free lunches.

Have you ever wheeled a loaded 80 with limited uptravel and big tires, with huge bumpstops to stop the tires from rubbing? These trucks are not buggies or rock crawlers. They need the up travel. Otherwiser you are on the bumpstops all the time. Not fun.

I can ask the same question. If we have the skillset at work to make a 80 do this, don't you think we can design a suspension?

This is not a pissing match. Just a thread about making the most of a 80 suspension.




So what size bumpstop are you running on the truck that you are showing lifted on the forklift? Also are the rear tires touching or not?



Ok, so you made it droop out a lot, with limited up travel. What happens when you drive this truck fast over bumpy roads? Will the uptravel be enough to not hit the bumpstops?



I would venture to say the resistance the front control arms to twist is way more than the resistance on the shock. The front shocks are hardly at an angle at the top, yes they have a little angle at the bottom. But is that resistance worth going to a shock converter and using a shock with a bushing that is way smaller than OME? What about the durability of the smaller bushing on high speed travel on dirt roads? The bushing size is one of the great features of OME.



The inbalance in a 80 suspension is due to the different designs of the links. There are tons of threads on here where people have tried, experimented, tested etc to get the front end to move. The only real fix is three or four link front.



True, the customers can decide, but they should be given all the facts. The OME is already a 10" /11" travel shock. Installing a longer shock with shock adapters will make it droop out more. That is not the question.

I am questioning why does fitting this stock allow you to run 35's with 2.5" of lift better than a regular OME shock fitted with 2.5" of lift? That is what you are saying. Just because you are increasing droop does not mean the tires fit better.

When you run taller lifts, you move the axle articulation away from the frame. The wheelwell is still the same size, so compressing the tire up into the wheelwell causes the same rubbing issues as before but the plane around which the artciculation happens is further away from the body. What does this mean? We get more up travel which is what these trucks need.

You can get away with very little up travel in buggies etc, but not on these trucks.

I am not attacking you, just sharing knowledge that we have gained over the years.

I dont feel like aswering each question today so hers a short sum up.

I am just building what they asked for and my PM box is pretty full,

IMHO that 80 has way to much travel, to much travel is as bad or worse than not enogh.

yes i have built more than one 80 and loaded down with gear, eveyone will not be wheeling these 80's as hard as ya think,if they need more performance than a bump stoped 80 running 315's then they will buy your 4" to 6 " kit with THE XXX EXTENDED SPRINGS.


the tires do rub the in the rear frame.....

 

[SUMOTOY]

yes i have built more than one 80 and loaded down with gear, eveyone will not be wheeling these 80's as hard as ya think...

I agree, cuz it can get expensive, and carries a huge footprint. I referred to offroading a lifted 80 to dancing with miss piggy in heels.

SJ