I'm needing info on designing a radius arm front straight axle. I've been lurking here for awhile and have yet to see a calculator for it. (probably because I'm blind) I'm seriously thinking about doing my 02 2wd GMC with an old 10 bolt and a divorced transfer case. But I won't even bother to start until I have the design worked out.

Basics for the conversion will be a coil spring chevy 10 bolt, long radius arms, a 4x4 steering box, and a divorced transfer case. I'm not going for a large lift, probably won't ever go over 315R16's. It will be a daily driver with the added abllity of a straight axle. Its currently running a basic 3 inch lift, I'm hoping to get away with only about 6 inches total with the SFA.

So what do we have for thoughts and calculators for doing this project?

I've even considered using a late model Dana 44 from a dodge but can't find info for a 6 lug conversion. If I could change it to chevy outers with hubs, it would be a better set-up I think. But I'm unable to locate such a set-up.

like that?

Yep, thats the idea. Was going to do a larger version of the XJ long arm kits. But I need to do it on paper first to make sure I don't run into stopping issues. Depending on the math I might have to have the long part of the link go to the top and the short link on bottom for clearence. Just need to do some math to figure out the exact layout. Anyone know of a calculator for a longarm type suspension?

Since you have to build the axle mounts anyways, why no 3 link?

Not going to be a hard core rig, not even going to be very tall. I like the radius arm set-up a bunch, call it personal preference, if I went to the effort of a 3 link I might as well go with a 4 link. I love the simplicity of the 2 link and it does provide a little bit of sway control on its own. I've been tossing around suspension designs for about 3 months now and I'm pretty sure I'm going 2 link. Just need some info on the actual layout for anti dive design.

Its my understanding that radius arm suspensions have inherently high ant-dive (anti-squat) characteristics.
Is that your goal?

IMO.
It would make sense in a front suspension to have anit-dive pretty high 70-90 percent.

I 3-linked my dakota with a Chev D44 front, and it rides retardly well on the road, but offroad is night and day over radius arms. Just my .02 anyways.

Radius arms are easier to design though. Just make the arms as long and flat as possible. With little lift, and mounting to the bottom of the frame you could essentially just copy a Bronco longarm setup and be golden.

the biggest difference between the radius arm and 3 link is the instant center on a radius arm is basically the pivot at the frame, producing high AS/AD numbers. and a 3 link basically one step more than a wristed radius arm setup.

i have the long (48") radius arms on my racer, it drives exceptionally well with airshocks on it.... 2.5 Fox 18 inch travel air shocks with 280 psi and 705ccs of oil to be exact... i hit a section of washboard and didnt know it... I hit a 1 foot tall waterbar and didnt feel it till the back tires cleared it. rides like a dream at speed. I was rallying it in the hills this last weekend, absolutely too much fun to drive.

application is a 3000 lb racer, though, and not a street vehicle. From what I hear, air shocks are not the best idea on the street. the radius arms work great, with heims, just make the panhard bar as long as you can physically fit it.

So not to highjack but if a radius arm setup produses high AD/AS numbers then would a 3 linmk setup where the uper ends meet at the same "hight" on the frame produce high AD/AS numbers as well?

That is true Y5.

But with a 3 link you have the ability to alter the AS/AD by repositioning the link spacing at the frame.

With radius arms you dont have that option.

That is true Y5.

But with a 3 link you have the ability to alter the AS/AD by repositioning the link spacing at the frame.

With radius arms you dont have that option.

unless you build it into the mounts.

I figure if you use a long enough distance between the axle and mount, you have less issues. if you had a couple of bolt holes to choose from, you could tune it.... if youre using coilovers, you could tune it with height adjustments.

AS/AD are more determined as far as i know by the instant center, the imaginary points at which the links would intersect if they were infinitely long. so if they met the frame at the same height, that does not mean that the IC meets there at the frame with them like they do with a radius arm setup. the closer to parallel the upper and lowers are in a 3 link, the farther out the IC is.

I happened to ride in an 04 toyota equipped with a 3 link and coilovers the other day. nice truck, but it has lots more dive in the front than my radius arms do.

I wonder if it was set up incorrectly. I know for a fact that the 100lb/in springs over 300 lb/in springs on the walker evans coilovers didnt help. it needs at least 150/250 or maybe 150/300 for springs to prevent the huge body roll that it had. flexes like mad, drives like shit. the previous owner didnt know how to set up the coilovers to make the most out of the trucks capabilities. after some tweaking with the coilovers, it is much better. When I first saw it, it had the sliders bottoming out before the 100 lb/in springs even got compressed, and was riding solely on the lower 300 lb/in springs. cornered well, but didnt have need for upper springs as they werent even being used. Having looked at the coils, I will have to take some time and map out the suspension on it to see what can be improved.