Hi Tawatree, yes, I'm in front of a computer, I'll explain in more detail.
My point was in an ideal world, the suspension links/geometry should never add any roll stiffness - that's the job of the springs (including, if required, an antiroll bar) We can't completely eliminate roll stiffness with radius arms, but it can be minimised.
I'll explain by starting with a one link.
A one link suspension consists of an A frame looking link with a single pivot at the chassis end. Lateral axle location is provided by a panhard rod or Watts Linkage. (so, yes, technically there are two links)
A one link offers no roll stiffness at all. It also has no means to adjust antisquat, and one links have very high antisquat.
The key factor with a one link is that its bolted/welded solidly to the axle housing. ALL the pivoting is done at the chassis end. Often a very large heim/jonny joint or even a trailer ball is used to provide high angularity.
Here is a photo of a typically agricultural looking one link. I'll stress again, these provide unimpeded travel (no roll stiffness induced by the links) with the axle end welded solidly to the housing.
In contrast, a "conventional" - (with the arms parallel to each other)" Radius arm suspension has very high roll stiffness. the bushes at the chassis end don't add much roll stiffness at all (if they're well designed) but the big issue is at the axle end. with parallel arms, (viewed from above) as one wheel rises and the other falls, in order to flex, the arms have to twist relative to each other around the axle housing. There's lots of rubber that has to be pushed around to make this happen, so that starts adding bind to the suspension. not in travel, but in flex. Manufacturers exploit this to make they cars understeer and to limit body roll.
In extreme cases, the axle housing starts to twist too once the bushes are fully bound up.
However, the more the arms are triangulated at the chassis end, the less the axle end bushes have to deform to achieve flex.
To prove my point, heres a simple experiment to prove the effect. It's not perfect but you'll feel my point.
Grab a pencil or pen and hold it between your finger tips like this:
Imagine this is looking down at your car from above and the pen is the front axle.
Now "flex" the front axle by cocking one wrist down and the other up:
Like so:
You will immediately feel the pen twisting in your fingers as you do this. That's what the bushes are there to allow but obviously they're inherently trying to fight that.
Now, if we triangulate our radius arms by putting our wrists together:
and then flex our axle, we're actually just rolling around a central point where our wrists meet, and the pen doesn't twist at all relative to our fingertips.
We've just (sort of) made a one link.
This is the easiest way I can describe the effect on roll stiffness of triangulating radius arms at the chassis.
There are practical limits however - trying to aggressively bring the arms together normally will add a deep crossmember under the gearbox and will cause issues for clearance and front driveshaft room.
I initially did this for packaging - I didn't want the arms under the chassis and I wanted the arms as far inboard of the wheels as possible to maximise steering angle/tyre room but it became clear there was a large improvement in roll stiffness.
Is there a magic formula? No, I don't think so, more is better, but there will be inevitable compromise around packaging.
The other issue with suzuki axles is that there ends up very little room around the diff on the driver's side.
Otherwise the advice would be to get the arms as flat as possible at ride height. Note that suzuki basically run their arms rising to the axle at ride height in a Jimny - this is to provide the best ride quality.
I hope this helps.
Whilst I subsequently converted my car to three link front TBH roll stiffness wasn't the major driver, it was about restoring compression travel and being able to run the car low as my flipped radius arms were sitting between the chassis and the axle.
