Long arm geometry question

[DaveB]

I have been looking at the geometry of my son's MJ front control arms relative to short vs long arm. I have looked at a bunch of long arm kits online and they come in lots of different styles. Some just lengthen the bottom arm, others tie the top to the bottom arm, and others lengthen both arms.
I broke out the drawing tools and did some scale drawings of the different types and how they move through their range of motion. The stock positions and stock arm lengths keep the axle caster fairly constant through a typical range of motion. The kits that only change the lower arm or tie the upper arm to the lower change the caster as the axle moves (although in opposite ways). I believe that the kits that lengthen both arms correctly should keep the caster angle closer to what it should be.
So those of you with long arms, what have you found that works best ?

 

[I Lean]

Depends on how much work you want to do. Doing a radius arm (upper arm tied to the lower) is definitely going to be easiest, and works quite well. The *ideal* is probably separate upper/lower arms like factory, just longer. Maybe Herzog can post pics of the front suspension on his XJ set up that way.

Long lowers and short, stock-positioned uppers works, but not as well as the other two. It's the least amount of work, but has some extra brake dive as a nice benefit.

Having built both, I'll vote for the radius arms. There just isn't a lot of room to make brackets easily for independent upper/lowers, and radius arms work well especially when you have leaf springs in the back.