radius arm vs 3link

[uninformed]

my thoughts....

flipping stock arms will not improve anything but clearance. Why? because the arm length is the same, the bush spacing the same, the relation between tyre contact patch and chassis mount the same, the bush type the same...NOW, if we are to insert some veribles....if on a stock set up, the stock arm at diff end, bushes center to center disect the centerline of axle shaft and then you flip them and now the bushes dont, you may have altered the axle roll axis in some small way...this may lead to slightly better feel over bumps and driving handling...BUT would be very hard to feel/measure.

Big Boy, the only way I can see your narrowd at diff end arms working better is if the bind is the same but now more axle out board the arm so it equates to more travel...BUT I am still sceptcial. I say there are to many varribles to what you have done and it has not been tested with just that one change, ie same bushes, tyres etc etc etc...

Brooksy is getting advantages through many small changes and I will be real interested to hear how they work for him...closer bush space, bigger bush rubber, longer arms, thinner arms, slight triangulation etc...

everyones needs are different, ie on road handling, service life vs out and out off road ability...But unless you are crawling, RA's set up for off road should work well on road to IMO

remember it can sometimes be hard to take our emotion out of the result (i think it is a good idea therefore it is...)

[uninformed]

Its very hard to discribe. Its more the deflective angle it takes when it hits a bump. Unless youve ridin in 1, its hard to discribe. But its kinda the same a going from 31" tyres to 35" tyres. How the bumps feel different. You dont feel the small ones anymore, but still do the big ones.

but is it better or just marsking a problem......if you change nothing but tyre size from a 31 to a 35, you have changed your anti dive and anti squat...as far as not feeling the small bumps, its because you have more side wall flex in the tyre and its doing a bit of shock absorbing....now the varibles are: rims size, tyre construction, tread type rubber compond, air pressure..

so all the flipped arms flex better. How many of the people that have done this #1 ONLY flipped the arms over and NOTHING else? #2 took acurate measurements before and after #1??

[uninformed]

the only thing atm I can think of for the flipped arm to flex better is maybe on a stock set up the arm rubs/binds a little on the axle case housing??? and then when fiipped clears this. I am not familiar with toy or nissan fronts so dont know their clearance at this point?

[TheBigBoy]

But see this is where your theory is out the window. If you jumped in my truck its instanly noticable. Especially to other 80 series owners.

No, the arms dont rub on the housing. Think of it this way. The arms in factory form never disected the centre axle point. Its was below this. Now you have flipped arms it is above the axle centre line point. Being higher on the housing its going to make your wheel appear to drop more while binding the same (example.. Its in a 2" lift location now and not 5"). But this aids the tuck because more pressure can be put on the wheel that doesnt tuck up as much now due to the new location. Ontop of that. I will say it just works better aswell.


If your not familiar with cruisers or patrols. I suggest you go do some recon before throwing theories out there. Otherwise your just adding to the confusion.

[TheBigBoy]

Its very hard to discribe. Its more the deflective angle it takes when it hits a bump. Unless youve ridin in 1, its hard to discribe. But its kinda the same a going from 31" tyres to 35" tyres. How the bumps feel different. You dont feel the small ones anymore, but still do the big ones.

but is it better or just marsking a problem......if you change nothing but tyre size from a 31 to a 35, you have changed your anti dive and anti squat...as far as not feeling the small bumps, its because you have more side wall flex in the tyre and its doing a bit of shock absorbing....now the varibles are: rims size, tyre construction, tread type rubber compond, air pressure..

so all the flipped arms flex better. How many of the people that have done this #1 ONLY flipped the arms over and NOTHING else? #2 took acurate measurements before and after #1??

Im just discribing the FEEL mate. I didnt change tyre size.

[uninformed]

Well I am familiar with rovers and what did toy and nissan copy??? yes there bush seperation is different and location, this may have some effect to Scanas for you, but the theroy is the same.

when the axle articulates there is a twisting force going on, this, along with the angular action is binding up the bushings.....now on stock arms, in normal postion, moving the chassis ends in towards each other \/ will help flex....im wondering of the opporsite is true for flipped arms, like Big Boy has done?


Now better ride by flipping them? well since on your rig the axle end bush disection line is below the axle shaft center in stock and now flipped it is above, I think this is changing the axle roll axis and if its gone from positive oversteer to neutral, well in theroy it should handle somewhat better....

more down flex, maybe your flipped arms work better than a stock arm on your lifted rig???? but I doubt any difference on a stock rig.

So my guess is it is working somewhat with your varriables but as its custom, there are better ways of doing it...IMO

[1MadEngineer]

so all the flipped arms flex better. How many of the people that have done this #1 ONLY flipped the arms over and NOTHING else? #2 took acurate measurements before and after #1??

ME, I had t o do all this as part of the development of the SF arms. I can tell you that in certain setups there was a reduction in binding of the panhard bushs due to the change in arc of rotation of the diff under forced articulation, results were small but none the less noticeable, then we put an adjustable panhard on with new bushs and got similar 'added' flex results. Diff regretion when using holey bushs did give a more supple ride, but the downside is the increase in antisquat when the wheel in trying to climb square ledges. There are advantages too though smaller obstacles allow the body to 'climb' the CofG marginally. So summarizing, there are benefits of both setups, but none that are very substantial IMO.

[TheBigBoy]

Well I am familiar with rovers and what did toy and nissan copy??? yes there bush seperation is different and location, this may have some effect to . for you, but the theroy is the same.

when the axle articulates there is a twisting force going on, this, along with the angular action is binding up the bushings.....now on stock arms, in normal postion, moving the chassis ends in towards each other \/ will help flex....im wondering of the opporsite is true for flipped arms, like Big Boy has done?


Now better ride by flipping them? well since on your rig the axle end bush disection line is below the axle shaft center in stock and now flipped it is above, I think this is changing the axle roll axis and if its gone from positive oversteer to neutral, well in theroy it should handle somewhat better....

more down flex, maybe your flipped arms work better than a stock arm on your lifted rig???? but I doubt any difference on a stock rig.

So my guess is it is working somewhat with your varriables but as its custom, there are better ways of doing it...IMO

Better ride by flipping them = Absolutely... Its rides 50% better and feels as good, if not better than the rear now.

More travel = Arm binding possition. I recon it gets a little more travel than factory possition. But as the location of the arm on the housing is higher. The drop appears huge, and that extra travel it gives gets taken up by the weight being forced to the tuck wheel (when crossed up)

[TheBigBoy]

so all the flipped arms flex better. How many of the people that have done this #1 ONLY flipped the arms over and NOTHING else? #2 took acurate measurements before and after #1??

ME, I had t o do all this as part of the development of the SF arms. I can tell you that in certain setups there was a reduction in binding of the panhard bushs due to the change in arc of rotation of the diff under forced articulation, results were small but none the less noticeable, then we put an adjustable panhard on with new bushs and got similar 'added' flex results. Diff regretion when using holey bushs did give a more supple ride, but the downside is the increase in antisquat when the wheel in trying to climb square ledges. There are advantages too though smaller obstacles allow the body to 'climb' the CofG marginally. So summarizing, there are benefits of both setups, but none that are very substantial IMO.

What he said.... I did it because im bored and wanted to know the results myself.

[Struth]

The way I see it, flipping arms would do two things. 1) improve crlearance, as mentioned. 2) Improve the arc in which the wheel travels when hitting a bump by flattening the RA's out.

Apart from spacing the diff mounts apart (NOT the distance between the bushes on the RA) when you change them around I dont see any other way it would help with flex.

The only thing that improves/changes the arc of the axle is the relationship between the RAs mounting point at the chassis and the centre line of the axle.

So either drop boxes or suspension height change will alter this relationship, flipping the arms alone does nothing.

As for flipped arms giving better artic' possibly.

Not shit stiring. But flipping the arms alone does give more travel than stock. Everyone who has done this has said it. And from what I have seen of my own. Its true.

But my question to the suspension guru's is. If moving the chassi end mounts in 30mm closer together gives you more flex, then so does moving them 30mm on the housing end. The closer you move either end into the radial point. The more flex. Wether its this /\ or this \/

I think you will get better wheel travel by moving the arms in on the axle, so you will get better flex. As stated by uninformed, this will be because there is more axle length outside of the radius arms which equates to better articulation/travel at the wheels.

I also think you will sacrifice some on road manners, but maybe nothing the addition of a swaybar for road use wont correct.

[TheBigBoy]

That the only thing I was worried about when I turned it in 30mm. Was body roll and road use. That was all cleared up after the first run. It drives better than before. Edit... I will say slightly more body roll.

Cranky has flipped his arms and not turned them inwards like I did. And he will say it got more travel aswell.

I like the terminology of more articulation because you have more axle outside of the new arm location arc. But that would suggest it would be the same a running 30mm spacer plates at your rims. And Im getting alot more travel than that.

[uninformed]

so all the flipped arms flex better. How many of the people that have done this #1 ONLY flipped the arms over and NOTHING else? #2 took acurate measurements before and after #1??

ME, I had t o do all this as part of the development of the SF arms. I can tell you that in certain setups there was a reduction in binding of the panhard bushs due to the change in arc of rotation of the diff under forced articulation, results were small but none the less noticeable, then we put an adjustable panhard on with new bushs and got similar 'added' flex results. Diff regretion when using holey bushs did give a more supple ride, but the downside is the increase in antisquat when the wheel in trying to climb square ledges. There are advantages too though smaller obstacles allow the body to 'climb' the CofG marginally. So summarizing, there are benefits of both setups, but none that are very substantial IMO.

Greg, do you think it is dependant on the bush seperation at axle end AND its relation to axle shaft center?? Ie lets say on #1 stock rig the arms go from 100mm lower than axle shaft center line to 100mm above and on rig #2 they are on center line stock and flipped....

[TheBigBoy]

If I understand your question correctly. Arent all factory radius arms dependant on the lower arm bush seperation? If the line from all 3 RA holes lined up and disected the axle centre point. It wouldnt make a difference what direction the arm took, over or under. But because it doesnt. The degression , has an affect on the arms orientation.

Or... Should I have said " the orientation of the arm has an affect on the degression" Ill learnt to use this new word yet.

[uninformed]

what Im saying is , take a straight line from the center of the 2 bushes (on 1 arm) at axle end, does this line intersect the axle shaft center line? On a rover it pretty much does. Nissan? Toy?

think of the chassis end as the instant center of a top link and bottom link...... weld them together and you have an RA

now on a rover, axle roll axis is based on the axle shaft center line to chassis bush center.....alxe roll axis will effect how the vehicle handles...roll steer/bump steer.... now as far as your flipped arms being flatter, what that means when it goes over a bump is that instead of the front end trying to move forward (as it would with a spring lifted stock arm) it now may well be moving the front end backward with the direction of force....smoother ride.

moving your RA's in at diff end alone, will increase bump steer....

[TheBigBoy]

Im sure I answered that in a previous post. No it doesnt disect the axle centre. In factory form it sits below this. I would agree with you about the bump steer if left underneath and not flipped. Because currently I have none. Can drive down the highway with 1 finger with minimal correction. The only problem I currently have is I havnt had time yet to raise my rear panhard mount. So my rolling axis is off.

[Struth]

now as far as your flipped arms being flatter, what that means when it goes over a bump is that instead of the front end trying to move forward (as it would with a spring lifted stock arm) it now may well be moving the front end backward with the direction of force....smoother ride.

....

Wrong, wrong, wrong....

flipping the arms has absolutely nothing to do with the arc of axle centre line which is what has to change to prevent the axle from travelling forward on up travel.

As can hopefully be seen here, unless you change the suspension height or the position of the radius arm at the chassis, the arc travelled by the axle centre line will not alter.

You must change the angle of the dotted line in the drawing below to achieive a different arc, changing the radius arm from under to over does not do this

[TheBigBoy]

I dont thnk thats what he was talking about struth. He is talking about the movement in the bush's. And if that diagram is correct then there should be no difference what so ever in road handling. Have you been in a flipped arm cruiser?

Your talking about the axle centre and the direct line of force back to the chassi point. That doesnt not change when only doing the flipped arm. And you are right. What your not taking into consideration is what the actual wheel does when it hits a bump. Because it does not disect the axle point. This changed when arms are in the flipped orientation.

[Struth]

I dont thnk thats what he was talking about struth. He is talking about the movement in the bush's. And if that diagram is correct then there should be no difference what so ever in road handling. Have you been in a flipped arm cruiser?

Your talking about the axle centre and the direct line of force back to the chassi point. That doesnt not change when only doing the flipped arm. And you are right. What your not taking into consideration is what the actual wheel does when it hits a bump. Because it does not disect the axle point. This changed when arms are in the flipped orientation.

Yep I can see what you mean, in an 80 series when standard the bush centre line is below the axle centre line, obviously it is opposite when flipped. I would reckon the difference would be very minimal however.

No I have not been in a vehicle with flipped arms.

[TheBigBoy]

This is my interpretation of why it drives so nice. I could be wrong but ill give it a go. Ive done the mods and seen the results, but now how to figure out why.

In the pic below, the red is the axle. The 2 circles below are bush's in standard form. And above in flipped. The force is coming from right to left. The green is supposed to be eqaul arcs of movement but im not a very good drawer.

The grey is the bolt sleeves and the blue is where the bolt sleeves want to end up when under force. Keeping the orientation to the axle. As you can see the bottom 1 wants to come back and up. This intern forces the tyre downwards.

The 1 above does the oppossite.



Sorry had to edit picture so it made more sence.

[uninformed]

now as far as your flipped arms being flatter, what that means when it goes over a bump is that instead of the front end trying to move forward (as it would with a spring lifted stock arm) it now may well be moving the front end backward with the direction of force....smoother ride.

....

Wrong, wrong, wrong....

flipping the arms has absolutely nothing to do with the arc of axle centre line which is what has to change to prevent the axle from travelling forward on up travel.

park that high horse for a minute and listen....if you have a spring lifted, stock arm rig and those RA's are down hill to axle at say 6 degrees when it up travels through its arc, it swings up and forward....basic geometry....now if that arm has been fixed to the top of the axle and is flat, when it moves up it will swings up and backwards....if your vehicle is moving forward, what do you think handles bumos better, a forward moving front axle or a rearward???? if you compare a flat/level arm and flip it to a flat level arm then there is no difference

what is happening with Big Boy's flipped arms is he is changing the front end geoometry...like rearanging the arms on a 3 link...change the axle mounting points up and down affects axle roll axis and anti-dive....panhard does the roll center.

why it would make 2 5ths of bugger all difference on a rover is becasuse the axle end disects the axle center line....if on a Nissan or Toy they are below by some amount and now above the difference is there for a change in axle roll axis


IMO

[TheBigBoy]

You just discribed my picture and thougths exactly.

[uninformed]

Im hoping Greg will confirm it for us...I could be very wrong hahaha... looking at the 2 pics, first Struth's what is deceeving in that pic is the dotted line that goes from chassis bush to axle center line, that doesnt change BUT what does is the amount of forward travel for givin up travel depending on the RA angle....hell thats simple, just think of a stock rig and then through some longer springs in of the same rate....the stock rig with its level arm will handle bumps better and hve better axle roll axis and roll steer....BUT to me this is dependant on the bush set up at axle end....like in Big Boy's pic there is a noticable difference in stock/under RA mount and top/flipped RA mount....on a rover very little difference.

[TheBigBoy]

Just another reason why cruisers are better than rovers .

And Im sure greg will just tear shreds off the theories and pictures. But at the end of the day. Im driving the thing, and it LOVES shopping centre speed bumps. Someone tell me why???

[Struth]

now as far as your flipped arms being flatter, what that means when it goes over a bump is that instead of the front end trying to move forward (as it would with a spring lifted stock arm) it now may well be moving the front end backward with the direction of force....smoother ride.

....

Wrong, wrong, wrong....

flipping the arms has absolutely nothing to do with the arc of axle centre line which is what has to change to prevent the axle from travelling forward on up travel.

park that high horse for a minute and listen....if you have a spring lifted, stock arm rig and those RA's are down hill to axle at say 6 degrees when it up travels through its arc, it swings up and forward....basic geometry....now if that arm has been fixed to the top of the axle and is flat, when it moves up it will swings up and backwards....if your vehicle is moving forward, what do you think handles bumos better, a forward moving front axle or a rearward???? if you compare a flat/level arm and flip it to a flat level arm then there is no difference

what is happening with Big Boy's flipped arms is he is changing the front end geoometry...like rearanging the arms on a 3 link...change the axle mounting points up and down affects axle roll axis and anti-dive....panhard does the roll center.

why it would make 2 5ths of bugger all difference on a rover is becasuse the axle end disects the axle center line....if on a Nissan or Toy they are below by some amount and now above the difference is there for a change in axle roll axis


IMO

It's not a high horse, I just feel the need to express my view strongly here, and that is that placing the radius arm above or below the axle makes absolutely no difference to which direction the axle travels on it's arc under compression, that arc will not change unless you alter the relationship between the RA chassis mounting point and the axle centre line, the dotted line in my drawing, flipping arms does not do this.

Flipping arms I may agree change the roll of the axle, I can't discount that yet as I need to ponder it.

Cheers

[TheBigBoy]

I aggree the compression arc wont change if its under or over. But the deflection in the bush's due the initial bump accounts for something. You would be ready to change religions if I took you for a spin.

[uninformed]

It's not a high horse, I just feel the need to express my view strongly here, and that is that placing the radius arm above or below the axle makes absolutely no difference to which direction the axle travels on it's arc under compression, that arc will not change unless you alter the relationship between the RA chassis mounting point and the axle centre line, the dotted line in my drawing, flipping arms does not do this.

Flipping arms I may agree change the roll of the axle, I can't discount that yet as I need to ponder it.

Cheers

but isnt moving the arm from the bottom to the top, akin to changing the mounts, axle end, on a 3 link to get better axle roll axis/bump steer etc...to me there are varriables which I have said, that is the bush disection of axle center line....remeber that dotted line is not a fixed arm...look at Big Boy's pic, if that top arm is level, the axle end moves rearward as soon as up travel starts, if it is the under mount and angled down to the axle it moves forward before it moves back during up travel....there has to be a point in a given arc, related to level where it is swinging forward or backward when traveling upward...



Edit: ok I think I know where we are getting confused...I think Struth is talking about using a stock arm in the STOCK axle housing mounts for RA, then yes nothing changes....but If you change and custom the axle end housing mounts, then you will get a difference???????

[TheBigBoy]

Ofcourse there is always varying points. As with the superflex arms that locate the housing 25mm further forward. I did so with my stock arm mounts aswell. Meaning the axle centre isnt directly in the middle of the 2 bush's. And is closer to the front bush. Also moving them closer toward the middle of the housing made me raise them a further 10mm higher. What ever Ive done though, it was the right decission.

Here uniformed. This pic will help you understand more.

[uninformed]

yeah, what my edit was saying (if I am correct) is both Struth and I are right....I was mostly talking about Big Boy's set up after seeing his pics...so in my mind I could see the difference from going an under arm RA in stock location to making new axle housing mounts and flipping. To me there is a difference in front end geometry, even disregarding the lateral change he made...but if you take a stock arm from under the axle housing and flip it over and use the same stock housing mounts and same springs nothing will change, those geometry points are still the same hence the Rover examples I gave....Can any of the stock arms be flipped over and mounted in stock mounts? do they clear the housing?

[uninformed]

Big Boy:

what rig?
what spring lift?
what tyre size?
what castor?

if it is working that is good tech mate

[TheBigBoy]

Big Boy:

what rig? 80 Series
what spring lift? 5"
what tyre size? 35's
what castor? Factory 3 degree's possitive

if it is working that is good tech mate