triangulating radius arms for flex?

[80's_delirious]

Have been reading this thread http://www.outerlimits4x4.com/ftopic177752.php and it got me thinking.

Soooo, for the sake of curiosity,

Would there be any gain in flex in a radius arm suspension set up if the radius arm mounts were modified so that they were triangulated similar to the lower links in a triangulated four link? ie; closer togther at chassis end, and mounted on the housing on an angle back to the chassis mount.

I am wondering if it would reduce binding of the radius arm and bushes in the mounting brackets on the diff?
Would it reduce stability on the road?
Would the chassis end bushes bind when articulating?

Without knowing a lot of the technicalities my thoughts are that it could allow the diff to articulate more easily as it would essentially be rotating from a narrower pivot/axis with the arms aligned a bit more to the centre point

[rockcrawler31]

Not a bad idea and i'd be interested to see the results. Maintaining a panhard rod you would still have lateral stability and rotational control.

I think the downside is that you would lose some roll stiffness which is pretty important on cross slopes and cornering. Lets face it, if you were building an offroad only vehicle from scratch you would go a multi link front i.e. a 3 or 4 link front. The only reason you would keep a radius arm front is if you need to get it registered and have some road manners, which defeats the purpose of having a floppy flexy front

My 2c anyway

[80's_delirious]

I wasnt thinking offroad only, more improving flex of a cruiser front end without major surgery, major expense or major compromise to its road manners.

Obviously by improving flex in general, it would have an effect on road manners to some extent.

[its aford not a nissan]

i think closer together at the chassie end wont help flex much , but closer together at the diff end will help , but then the diff gets in the way

[Wendle]

Would there be any gain in flex in a radius arm suspension set up if the radius arm mounts were modified so that they were triangulated similar to the lower links in a triangulated four link? ie; closer togther at chassis end, and mounted on the housing on an angle back to the chassis mount.

Yes, the closer together you bring them, the less bind there is. If you take it to the extreme and bring them all the way in so they pivot on the same plane, there is obviously no bind at all.

but closer together at the diff end will help , but then the diff gets in the way

Not for long
Do that and you'll be leaving the diff somewhere along the road after it flops around and your tyres destroy the front of your car

[KiwiBacon]

Have been reading this thread http://www.outerlimits4x4.com/ftopic177752.php and it got me thinking.

Soooo, for the sake of curiosity,

Would there be any gain in flex in a radius arm suspension set up if the radius arm mounts were modified so that they were triangulated similar to the lower links in a triangulated four link? ie; closer togther at chassis end, and mounted on the housing on an angle back to the chassis mount.

Yes it will, that's exactly what I was talking about.

[80's_delirious]

cool

something to add to the pipe dream list

[uninformed]

if using stock arms, i would have thought that any triangulation, either in or out would result in binding earlier..... but if you move them closer together parrallel they will bind the same but the axle ends will move more due to the longer arc(distance from arm to wheel)

now if building arms from scratch you could make more improvements to the axle end bush center to center distance and the size of the bush.....plus make the things damn long....but still keep them parrallel

just my opinion

serg

[KiwiBacon]

if using stock arms, i would have thought that any triangulation, either in or out would result in binding earlier..... but if you move them closer together parrallel they will bind the same but the axle ends will move more due to the longer arc(distance from arm to wheel)

now if building arms from scratch you could make more improvements to the axle end bush center to center distance and the size of the bush.....plus make the things damn long....but still keep them parrallel

just my opinion

serg

A triangle doesn't bind. It pivots on the point.

[uninformed]

if using stock arms, i would have thought that any triangulation, either in or out would result in binding earlier..... but if you move them closer together parrallel they will bind the same but the axle ends will move more due to the longer arc(distance from arm to wheel)

now if building arms from scratch you could make more improvements to the axle end bush center to center distance and the size of the bush.....plus make the things damn long....but still keep them parrallel

just my opinion

serg

A triangle doesn't bind. It pivots on the point.

and a trinagle only has 3 points.... a pair of radius arms has 5......

im thinking the relationship between the front right bush and left rear (axle end), and vise versa comes into play....

Serg

PS. i can understand that a 1 link + panhard is a trinagle, but its not 2 radius arms with triangluation.... plus it doesnt have the good points of a radius arm set up.

[KiwiBacon]

and a trinagle only has 3 points.... a pair of radius arms has 5......

im thinking the relationship between the front right bush and left rear (axle end), and vise versa comes into play....

Serg

PS. i can understand that a 1 link + panhard is a trinagle, but its not 2 radius arms with triangluation.... plus it doesnt have the good points of a radius arm set up.

Think about it a little more.
Triangulated radius arms behave exactly the same as a monolink, the front bushes (holding arms to axle) do not deform as it flexes.

[uninformed]

and a trinagle only has 3 points.... a pair of radius arms has 5......

im thinking the relationship between the front right bush and left rear (axle end), and vise versa comes into play....

Serg

PS. i can understand that a 1 link + panhard is a trinagle, but its not 2 radius arms with triangluation.... plus it doesnt have the good points of a radius arm set up.

Think about it a little more.
Triangulated radius arms behave exactly the same as a monolink, the front bushes (holding arms to axle) do not deform as it flexes.

surely for that to work though the chassis ends would have to share the same mount, so you are a monolink........ if you simply trangulate 2 radius arms by moving the chassis ends closer to center by, say 100mm each they will still bind....

Serg

[1MadEngineer]

??? how much flex do you REALLY need, or is it just for w@nk value?

http://www.outerlimits4x4.com/ftopic172543.php
driveability and proven performance - no surgery required!

[uninformed]

??? how much flex do you REALLY need, or is it just for w@nk value?

http://www.outerlimits4x4.com/ftopic172543.php
driveability and proven performance - no surgery required!

pimp or whore..... im not sure which to call you lol

but for me its just trying to get a better understanding of whats going on.....after all im just a web wheeler

Serg

[KiwiBacon]

surely for that to work though the chassis ends would have to share the same mount, so you are a monolink........ if you simply trangulate 2 radius arms by moving the chassis ends closer to center by, say 100mm each they will still bind....

Serg

If you've only moved them in 100mm then they aren't triangulated.

[KiwiBacon]

??? how much flex do you REALLY need, or is it just for w@nk value?

http://www.outerlimits4x4.com/ftopic172543.php
driveability and proven performance - no surgery required!

I don't like the idea of two arms with different flexibility. I know driver reports say they can't tell the difference. But I still don't like it.

[Strange Rover]

Did this exact same thing back in 2003...

http://www.pirate4x4.com/forum/showthre ... ight=buggy

Probably wouldnt put it in a daily driver though...couldnt imagine how you could move the mounts easily and still clear everything...could work if you ran drop boxes though and moved everything inwards.

Sam

[1MadEngineer]

pimp or whore..... im not sure which to call you lol

yeah why would you want to use something that is actually good on and offroad and is a proven comp winner!



what would i know?

[uninformed]

pimp or whore..... im not sure which to call you lol

yeah why would you want to use something that is actually good on and offroad and is a proven comp winner!



what would i know?

mate take a step back. yes you know your shit, no question there, but did you add to this thread or did you just rehash another. i know you designed them etc. but it doesnt pertain to what we are talking about..........yes they may be better but why not add some help here, im sure you could....

Serg

[uninformed]

surely for that to work though the chassis ends would have to share the same mount, so you are a monolink........ if you simply trangulate 2 radius arms by moving the chassis ends closer to center by, say 100mm each they will still bind....

Serg

If you've only moved them in 100mm then they aren't triangulated.

not to split hairs, but every 4 link that ive seen called triangulated or double triangulated doesnt meet in the middle........but anyway Sam has shown it works......still vague to me but ill keep trying to get it.

i really do suck at this

Serg

[KiwiBacon]

not to split hairs, but every 4 link that ive seen called triangulated or double triangulated doesnt meet in the middle........but anyway Sam has shown it works......still vague to me but ill keep trying to get it.

i really do suck at this

Serg

Fair comment.

Basically what makes radius arms bind is the chassis ends of the arms being forced to move vertically as the axle articulates. This change in height is taken by flex in the mounting bushes (mainly at the axle end) and flex in the arms themselves.

As you bring the chassis end of the arms in closer together, the amount the arms and bushes have to flex decreases for the same amount of axle articulation.
If you could triangulate the arms then there'd be no vertical movement needed and no arm or bush flex. It'd just freely pivot, controlly by the springs and dampers.

But as you know making them meet at a point is pretty tricky, but the closer you get to it, the less roll stiffness the radius arm suspension will have and the easier the front axle will articulate.

[uninformed]

not to split hairs, but every 4 link that ive seen called triangulated or double triangulated doesnt meet in the middle........but anyway Sam has shown it works......still vague to me but ill keep trying to get it.

i really do suck at this

Serg

Fair comment.

Basically what makes radius arms bind is the chassis ends of the arms being forced to move vertically as the axle articulates. This change in height is taken by flex in the mounting bushes (mainly at the axle end) and flex in the arms themselves.

As you bring the chassis end of the arms in closer together, the amount the arms and bushes have to flex decreases for the same amount of axle articulation.
If you could triangulate the arms then there'd be no vertical movement needed and no arm or bush flex. It'd just freely pivot, controlly by the springs and dampers.

But as you know making them meet at a point is pretty tricky, but the closer you get to it, the less roll stiffness the radius arm suspension will have and the easier the front axle will articulate.

this is where im getting confused, and im hoping Sam will chime in. I thought that the binding was mostly at the axle end? given that a stock rover arm will have a fair amount of up and down travel when the axle housing is removed(ie: arms just fixed with oem bushes at chassis end)

if this is the case, why does moving the chassis end in change them. I can visualise the monolink, but would have thought that moving them in a small amount, like Sam did on his buggy, would have not made a difference................................................

Hang on......

if you draw a line from radius arm chassis mount to radius arm chassis mount, the center of this is the imaginary pivot point????? so if they join at IPP they simply rotate, not bind.....if they are back out to parrallel they bind....anywhere closer to IPP will reduce binding from lets say 100% at parrallel to 0% at IPP....... is thats whats happening?

Sam, what negative effects did the buggy have from its set up?

cheers, Serg

[KiwiBacon]

this is where im getting confused, and im hoping Sam will chime in. I thought that the binding was mostly at the axle end? given that a stock rover arm will have a fair amount of up and down travel when the axle housing is removed(ie: arms just fixed with oem bushes at chassis end)

The flex is mostly at the axle end because of the arm design. If you had really flexy arms you'd see them curving a lot and the axle bushes not doing as much.

if this is the case, why does moving the chassis end in change them. I can visualise the monolink, but would have thought that moving them in a small amount, like Sam did on his buggy, would have not made a difference................................................

Hang on......

if you draw a line from radius arm chassis mount to radius arm chassis mount, the center of this is the imaginary pivot point????? so if they join at IPP they simply rotate, not bind.....if they are back out to parrallel they bind....anywhere closer to IPP will reduce binding from lets say 100% at parrallel to 0% at IPP....... is thats whats happening?

Sam, what negative effects did the buggy have from its set up?

cheers, Serg

Sounds like you're getting it.

[80's_delirious]

pimp or whore..... im not sure which to call you lol

yeah why would you want to use something that is actually good on and offroad and is a proven comp winner!



what would i know?

mate take a step back. yes you know your shit, no question there, but did you add to this thread or did you just rehash another. i know you designed them etc. but it doesnt pertain to what we are talking about..........yes they may be better but why not add some help here, im sure you could....

Serg

well said Serg

Awesome tech 1madpimpwhoreengineer

no-one is questioning your knowledge or your product, there is more than one way to skin a cat, and spending a large wad on radius arms aint in the picture here

??? how much flex do you REALLY need, or is it just for w@nk value?

you could say the same about the product you ar flogging too

[80's_delirious]

this is where im getting confused, and im hoping Sam will chime in. I thought that the binding was mostly at the axle end? given that a stock rover arm will have a fair amount of up and down travel when the axle housing is removed(ie: arms just fixed with oem bushes at chassis end)

The flex is mostly at the axle end because of the arm design. If you had really flexy arms you'd see them curving a lot and the axle bushes not doing as much.

if this is the case, why does moving the chassis end in change them. I can visualise the monolink, but would have thought that moving them in a small amount, like Sam did on his buggy, would have not made a difference................................................

Hang on......

if you draw a line from radius arm chassis mount to radius arm chassis mount, the center of this is the imaginary pivot point????? so if they join at IPP they simply rotate, not bind.....if they are back out to parrallel they bind....anywhere closer to IPP will reduce binding from lets say 100% at parrallel to 0% at IPP....... is thats whats happening?

Sam, what negative effects did the buggy have from its set up?

cheers, Serg

Sounds like you're getting it.

this is what I pictured. In std form the diff housing wants to twist, pivot or rotate around an imaginary pivot point, but to do this one arm twists up, the other twists down, as the arms are parallel and oriented away from the pivot point (they will never converge on a central point) they end up working against each other and bind.
With the arms triangulated,the housing still rotates around more or less the same point, but the arms are radiating out from closer to a central point, so they will work with each other not against each other.

hard to explain

try cutting a square of stiff cardboard, hold one edge down on the edge of the desk and twist the other edge, the cardboard has to flex or twist along the full diagonal length. Now trim two sides off so the ends are triangulated in, hold the narrow edge down on the desk and twist the other edge, it will twist a lot more easily, because you have decreased the length of the diagonals, and shortened the separation between the pivot points, so it is closer to having one central pivot point.

[KiwiBacon]

try cutting a square of stiff cardboard, hold one edge down on the edge of the desk and twist the other edge, the cardboard has to flex or twist along the full diagonal length. Now trim two sides off so the ends are triangulated in, hold the narrow edge down on the desk and twist the other edge, it will twist a lot more easily, because you have decreased the length of the diagonals, and shortened the separation between the pivot points, so it is closer to having one central pivot point.

NIce explanation.

[1MadEngineer]

pimp or whore..... im not sure which to call you lol

yeah why would you want to use something that is actually good on and offroad and is a proven comp winner!



what would i know?

mate take a step back. yes you know your shit, no question there, but did you add to this thread or did you just rehash another. i know you designed them etc. but it doesnt pertain to what we are talking about..........yes they may be better but why not add some help here, im sure you could....

Serg

well said Serg

Awesome tech 1madpimpwhoreengineer

no-one is questioning your knowledge or your product, there is more than one way to skin a cat, and spending a large wad on radius arms aint in the picture here

??? how much flex do you REALLY need, or is it just for w@nk value?

you could say the same about the product you ar flogging too

pimpwhore? what am i selling? i don't sell them, i don't work for them. I do contract engineering design work, submit my design and a report and thats it.

So let me get this you want huge flex, for no money!
Maybe if you got off your high horse and read the thread and maybe the nissan one as well you might learn something. "GOOD" Flex is not all about how much travel you have. Otherwise stop paying out on someone who was willing to help, and give us some real info? what vehicle, what sort of driving, what modifications do you have or intend to do?

For instance in a nissan, guys always wanted BIG flex in the front! well (if you read the superflex thread) We got an average lifted nissan and flexed it to the limits of ALL the components and recorded the results. IE Stock radius arm geometry bound @ 11" of travel differential as measured accross the shock mounting surfaces, at ~12-14" the tailshaft bound and hit the x-member, then at ~14" of travel the steering linkages and TRE failed due to the steering geometry. Also the majority (~95%) of OE shocks only have 10" of available travel.

So now we had some REAL design parameters - to come up with a solution that would provide 12-14" of useable travel. WHY design something that can give 30" of travel if it cost thousands in components to match??

Then there is the loss of chassis reaction (or feel) by negating the influence that radius arms create. In std'ish geometry they utilise the 'torque tube' type effect of the front diff and the mounting bushes to induce roll stiffness back into the chassis. The only way to get this back by putting a swaybar back in. So by triangulating the mounts you have reduced a small amount of bush compression/bind but lost a lot of the good points. the only thing you haven't changed is the AS/AD in the neutral or flat position. If you can imagine std geometry the 2 outer radius arms are like levers from the front diff, so when on a side angle andthe body is flexing over, if you 'power on' to induce AS the arms push up on the chassis at a wide point which tends to want to level or even out the vehicle, now imagine they are pivoting in the middle of the vehicle - the force from the diff thru the lever arms pushes UP in the center of the vehicle which offcamber might be a lot closer to the CofG (remeber the car is on an angle and leaning over) this means its wanting to lift the body at an undesireable point.

With ALL this stuff there is compromise, every situation has its own specific issues. And sadly there is no silver bullet!

hope that sorta helps.

[80's_delirious]

hope that sorta helps.

yeah, cheers. far more intersting than your previous posts
Id guess that lots would also think that you are selling superflex arms, you do a good job of plugging them

[Strange Rover]

[pimpwhore? what am i selling? i don't sell them, i don't work for them. I do contract engineering design work, submit my design and a report and thats it.

So let me get this you want huge flex, for no money!
Maybe if you got off your high horse and read the thread and maybe the nissan one as well you might learn something. "GOOD" Flex is not all about how much travel you have. Otherwise stop paying out on someone who was willing to help, and give us some real info? what vehicle, what sort of driving, what modifications do you have or intend to do?

For instance in a nissan, guys always wanted BIG flex in the front! well (if you read the superflex thread) We got an average lifted nissan and flexed it to the limits of ALL the components and recorded the results. IE Stock radius arm geometry bound @ 11" of travel differential as measured accross the shock mounting surfaces, at ~12-14" the tailshaft bound and hit the x-member, then at ~14" of travel the steering linkages and TRE failed due to the steering geometry. Also the majority (~95%) of OE shocks only have 10" of available travel.

So now we had some REAL design parameters - to come up with a solution that would provide 12-14" of useable travel. WHY design something that can give 30" of travel if it cost thousands in components to match??

Then there is the loss of chassis reaction (or feel) by negating the influence that radius arms create. In std'ish geometry they utilise the 'torque tube' type effect of the front diff and the mounting bushes to induce roll stiffness back into the chassis. The only way to get this back by putting a swaybar back in. So by triangulating the mounts you have reduced a small amount of bush compression/bind but lost a lot of the good points. the only thing you haven't changed is the AS/AD in the neutral or flat position. If you can imagine std geometry the 2 outer radius arms are like levers from the front diff, so when on a side angle andthe body is flexing over, if you 'power on' to induce AS the arms push up on the chassis at a wide point which tends to want to level or even out the vehicle, now imagine they are pivoting in the middle of the vehicle - the force from the diff thru the lever arms pushes UP in the center of the vehicle which offcamber might be a lot closer to the CofG (remeber the car is on an angle and leaning over) this means its wanting to lift the body at an undesireable point.

With ALL this stuff there is compromise, every situation has its own specific issues. And sadly there is no silver bullet!

hope that sorta helps.

So are these things legal/engineerable to drive on the road???

I would imagine running two different radius arms would create some quirky handling issues....like jacking of the RHS under hard breaking?

Sam

[1MadEngineer]

So are these things legal/engineerable to drive on the road???

I would imagine running two different radius arms would create some quirky handling issues....like jacking of the RHS under hard breaking?

Sam

yep, they are engineerable down south with a swaybar as far as i have been told (nothing is in QLD ).

the difference in AD under braking is slighlty more noticeable, but it is sorta propotional to the drive point length differential of having a constant driven tailshaft offset to one side. Its a real balancing act, and one that took a lot of perfecting, and partly the reason for having a feasable limit to flex. I spose its sorta like - its better to have a soft shocks out wide then stiff shocks closer to the center. more control over a wider range of motion. I also did a heap of emergency braking test and as you can imagine, once the bushs got to full compression they exert very similar forces as no further longitudinal displacement is available. (the trick is they are not the same bush diameters )