Nice, good find on that thread.
I'll just show you my personal results to sort of go along with what's in that thread.
I recently finished doing a radius arm-style front on my XJ, with an 'upper' arm on each side. I did that for more on-road characteristics than anything else, and I figured I'd try it like that first offroad, and if it led to binding then I had designed it to be strong enough with just a single arm. As of now, that second upper arm hasn't been the cause of any binding issues.
The arms are slightly more angled than true 'radius' arms the way I built it...I did this for clearance issues and also to help ease some of the lateral stresses from the panhard mount. Here's a pic of the angle on the arms, and you can also see where the upper arm branches off. Never mind the somewhat bent D30 mount, that happened before the radius arms.
The standard 'upper' mounting, using a heim joint at the mid-arm mount, and the stock UCA bushings on the axle.
Here's with the system fully flexed, at least to the limits of the too-short shocks I have now. You can see that the johnny joints are doing all of the work:
and the axle end bushings really aren't doing anything:
Here's what the movement of the arms looks like:
Overall, I've been really happy with it. I haven't logged many road miles with it, as it's not insured at the moment, but I've had it up to 60 mph or so and it felt great. On the trail, it flexes not necessarily 'better' than the short arms did, but a lot easier - the axle seems to travel much more freely than it did before. Like, what I thought was a stiff coil spring rate before, was partially binding. Since installing the longarms the leaf springs aren't doing as much as they used to.
The biggest question is in terms of hill climbs and stuff - and honestly, I didn't notice it that much. The front felt stable enough that I was comfortable on steep climbs, however like I mentioned before, my shocks are basically limiting downtravel right now. Maybe with longer front shocks I'd notice more of a difference.
I haven't had experience driving a 3-linked front yet (well, assuming that means 3-link + panhard), so I can't directly compare the two. I just figured I'd share some development experience with a radius arm setup.
