Not quite three link.....

[simonr]

Not a new idea by any means - but I can't see any reason it will not perform every bit as well as 3 link off road:

First hack off the end of one of your hockey sticks. Then make up some solid bushes for the other hockey stick:

Then mount remaining bit of hockey stick as normal:

and

Then try jacking up one side of the vehicle. Before this mod, the front would stop articulating with about 2" of extension left in the shocks (which are +2" with lowered turrets). Now, the shock is the only limiting factor. With the shock removed, the HiLift was the limiting factor.

Although this does not really show how it will articulate in the field, it does show that the front & rear are balanced up to that angle. There is 3" more shock travel on the back so it will go a bit further.

What is the reason for the solid (Nylon) bushes?

When you accelerate or brake, the axle tries to rotate. The only thing stopping it rotating is normally the four hockey stick bushes. Since I have removed the effect of two of them, the remaining two need to be stiffer to result in the same roll.

The single remaining bush in the modified arm is a medium polybush.

Why doesn't everyone do this? Because it adds asymetry to your steering. Cornering left, the castor angle is increased and cornering right, it is reduced. The steering appears to self center OK on the road (with a little extra toe-in). It does roll some if you try cornering fast though - but this would be true of 3 link as well.

I'll be at Slindon on Sunday to try it out in anger! I have high hopes. Think I might have to have a look at detachable anti-roll bars now to make it a bit more civilised to drive on the road at any speed.

Si

[Hybrid_From_Hell]

Si

Very Very interesting (in a sort of slightly frighening sort of way ) seems like your definately onto something here, I know front suspension thoughts have been rattling around in your mind for quite some time...

Look forward to report and pics

Nige

[LR90]

Well it's one simple way to stop the front bushes binding. Good luck with the field trials.

[MogLite]

I'll certainly work

What plod/insurance/MOT would say is anybodies guess as its obvious a key part of your suspension is missing

You'll be needing an SVA

I'd be more tempted to try a "wristed arm"

Common in the Bronco world

the red thing is a pin to lock it out on the road.

[Michele]

Good luck on road!

Keep us posted...

[Tonk]

Good luck on road!

i think he's gonna need it

interesting though

could you not put swivels where the bush is at the chassis end, same effect, less twist though i would assume

[Michele]

Common in the Bronco world

Then you may want this

but it's always a compromise,and there's a thread on the P44 BB in which Sam (Strangerover)

suggests not to use it on his own experience...

I never tried one so I can't really say.

[Lewis]

I'm very interested in how this turns out Si.

I've been looking at ways to increse front droop, - currently on Gwyn Lewis/Llama 4x4 raised turrets with long dampers and worn metalastic bushes in narrow front arms. I had been considering void bushes/drilled polybushes but was concerned by the alarming wear rate and tendency to twist under torque.

Could probably (if i can find them) bring some narrow radius arms to Sodbury if that helps?

Lewis

[Hybrid_From_Hell]

Then you may want this

but it's always a compromise,and there's a thread on the P44 BB in which Sam (Strangerover)

suggests not to use it on his own experience...

I never tried one so I can't really say.

can you post up the link ?

and why not use a locking one then ?

Nige

[Michele]

and why not use a locking one then ?

Hey Nige!

That's lockable (pin-n-able?),you get out of the truck > un-pin > wheel > get out again > pin

(uhm)

I may have saved the link in my favs,I'll search...!

In the meanwhile check the original page out:

hinged radius arm by Quinn D.

(you may already know it,it's a bit dated)

[Daan]

Simon,

I have thought about this one, and tried it by removing one bolt. The problem is under braking: you removed the antidive on one side. So this will result in some weird results while braking hard. I would certainly consider the solution for a trailered vehicle, but if it were to be used on the road, not so sure. The hinged version as shown does give you better results I think.

Daan

[simonr]

What I've built is a first step towards this:

I wanted to make sure the idea worked before embarking on a load more fabrication.

One of the issues with the pin-lockable one above is the centre of rotation of the axle being further away from the axle itself. Ideally it would be on the center line of the axle but the further away you go the more of a steerage component is added as it articulates. This just increases the asymetry and makes the steering feel even more 'funny'.

Si

[white90]

Sam from Outer limits

Builder of MOGROVER

tried the wristed arm and binned it

http://www.outerlimits4x4.com/viewtopic.php?t=7718

[will_warne]

Simon, have a word with Filthy Boy; he ran a hinged radius arm on his 90 for quite a while. In fact I think he stated with a bought in one then went on to make his own.

I looked at doing this fairly seriously and, although it is a very simple bolt on mod, there seemed to be some major handling issues. The problem seemed to be axle rap on the hinged side when climbing, or decending, steep hills: not the time you want an unpredictable vehicle. I think you're solid bushes should help, as should pushing the centre of rotation further towards the axle, however I still think there may be some scarey handling issues.

[simonr]

Simon, have a word with Filthy Boy; he ran a hinged radius arm on his 90 for quite a while. In fact I think he stated with a bought in one then went on to make his own.

See, that's the trouble. Lots of people have an opinion about this idea (mostly that it's rubbish) but there are very few who have tried it themselves.

The problem seemed to be axle rap on the hinged side when climbing, or decending, steep hills: not the time you want an unpredictable vehicle. I think you're solid bushes should help, as should pushing the centre of rotation further towards the axle, however I still think there may be some scarey handling issues.

The handling of most off-roaders is 'interesting' to start with! The 'Axle rap' (is that a made up expression?) should only directly affect castor angle. As it rotates, admittedly you will get a small steerage component but I doubt that will be noticable.

I did wonder about the roll of the axle trying to rotate the standard hockey stick which in turn will translate into forcing body roll. This might cause a problem if you are on the brink of tipping over - but then so might the torque roll caused by your prop shafts both turning the same way on a car without this?

Apart from the extreme body roll - it doesn't feel that different on the road. We'll see if I die on the way to Slindon though!

Si

[D9OSV]

Last year i snapped a radius arm between the bushes....

But did not realise and continued to drive the vehicle on road and offroad for about a week, cos i diddn't have time to check what was wrong.......

Offroad awesome..

The vehicle stayed level and felt very positive.

On road it would dive under braking and felt very........errrrrrr Dodgy..

I have also driven a professional built hinging arm and also vehicles with three link.......

Result...Well, fine offorad but and on road if you are preppared to except that the handling is not going to be as good as standard.

The ultimate front suspension...?? I really don't know, but i do know that it needs more of us pushing the boubndarys and trying to find it..

Crack on Simon Looking good B)

Jim

[will_warne]

See, that's the trouble. Lots of people have an opinion about this idea (mostly that it's rubbish) but there are very few who have tried it themselves.

The handling of most off-roaders is 'interesting' to start with! The 'Axle rap' (is that a made up expression?) should only directly affect castor angle. As it rotates, admittedly you will get a small steerage component but I doubt that will be noticable.

I did wonder about the roll of the axle trying to rotate the standard hockey stick which in turn will translate into forcing body roll. This might cause a problem if you are on the brink of tipping over - but then so might the torque roll caused by your prop shafts both turning the same way on a car without this?

Apart from the extreme body roll - it doesn't feel that different on the road. We'll see if I die on the way to Slindon though!

Si

Haha, its sort of made up; it should read wrap. The spelling thing again

Yes, your setup should help the handling given that the pivot is as close to the centre of the axle as possible. A little while ago I did some drawings for a setup which would've gone further but would have been very difficult to make. The basic idea was that a smooth collar would be welded to the axle tube in place of one of the radius arm mounts. The radius arm mount would be a 2 peice cylinder that would fit over the colar and bolt together. This would move the pivot to the centre of the axle tube. PITA to make but it could work.

My latest idea is to do something along the lines of the Dobsons X-link. Its a really, really nice idea that would allow you to use standard radius arms and chassis mounts although the axle casing needs a fair bit of work. I'm not even going to try and explain it because its quite difficult to but, if you look at a picture, you soon see how it works. Because its a system that can be totally locked out it gives the best of both worlds: good (well for an even vehicle) on road handling and superb articulation when you remove a pin.

Oh, and Jim's right. This is an area not many people have looked at and I think there are some interesting possibilities.

[Daan]

See, that's the trouble. Lots of people have an opinion about this idea (mostly that it's rubbish) but there are very few who have tried it themselves.

- but then so might the torque roll caused by your prop shafts both turning the same way on a car without this?

Apart from the extreme body roll - it doesn't feel that different on the road. We'll see if I die on the way to Slindon though!

Si

Not saying your idea is rubbish, cause it does work for more articulation. Keep it coming!

The bodyroll issue under acceleration can be affected in a positive way, in that if you fit the standard radius arm to the left, it will counteract against bodyroll caused by the props. This depends on the diffratios, in my case with 4.75 diffs, the torque from te props is much less than it would be with 3.54 diffs and On my vehicle, I hardly notice influence due to this. The bodyroll under braking is harder to fix.

How much suspension travel are you running? In my case, I run 10 inch shocks and on full stuff, the axles actually do hit the stops, So I am not concerned about more travel.

I fitted radius arms to the rear as well, and although my suspension travel is not anywhere near as much as some people out there, the fact that it is well balanced, it has been very effective off road and on the road.

Daan

[simonr]

Daan, you are quite right. The hinged arm should be on the right (drivers) side. The lean generated by prop shaft torque combined with axle roll is quite pronounced.

I've done a bit of road testing today - 30 miles worth - and once you learn how it behaves, it's not too bad.

I have come to an unusual conclusion though. I think what it needs is roll-damping. After all, you rarely if ever need the articulation to happen fast. On the road, it tends to be sudden changes which cause problems as you cannot react fast enough.

Something like this to start with:

I'll mount it across the hinge so the damper moves as the hinge flexes.

It's just a regular ram filled with ATF with rate adjusters on either end - so you can control the compression & rebound separately. Made as a steering damper for the electric bar stool. May turn out not to be strong enough - but will prove the concept.

I mighe even be able to adjust it so the hinged arm exactly cancels torque roll (as per Daan's post).

I think the combination of these might make it a lot more civilised.

Si

[T1G UP]

will this pinned arm arangement work aswell as a 3-link? would you leave the nearside arm alone or still cut one bolt lug off??

would be a great cheap mod.

[Daan]

I can see the roll damping working; its more common on track racing.

I also remember you having quite soft springs. It might be a case of going slightly stiffer, which you can afford with this setup and is mazbe needed for side slopes. But Double shocks could be more effective, If you have not done so already.

Keep us posted!

Daan

[filthy boy]

As Will said I ran a hinged arm. First a bought one and then redesigned and fabricated to improve a number of things.

For mucking around on playdays, driving down flat boulder filled rivers and, most importantly, parking on big ramps at shows, it is a bolt on way to get loads more front end articulation. I have some great pics to illustrate this and liked it for some time.

The unpinned handling on road you can just get used to but tight windy mountain roads on the Cevenol were interesting!

The real problem, and why I gave up with it, is when you get the front end up a big step and try to accelerate to bring up the rear (ie unweighted front end) it torque steers like mad to the unhinged side. Scary when climbing steps with a big drop / cliff on 1 side! Same whatever you put the hinge.

So there you go, the opinion of a man who did it. Not too bad if you stay on the flat.

FB

PS When redesigning the arm we did a FEA of the standard arm. It is a great piece of design. The fabricated I beam from plate type is nowhere near as good strength wide. We machined from solid billet steel of some stupidly expensive and strong type.

[dollythelw]

hows about a ram to act as a lockout? put a line lock in for launching and leave it open for twist......... or a flow control valve to act as a damper (that would slow the systems reaction time)

just random ramblings.. I need more coffee

[MogLite]

So there you go, the opinion of a man who did it. Not too bad if you stay on the flat.

Brilliant - real world feedback

[filthy boy]

Brilliant - real world feedback

Thanks.

All the rams and hydraulic locks won't remove the torque steer.

FB