With the average mini-trucker comes the stigma that "do-it-yourself" is the way to go. Well, we're here to say that there's a reason professionals and engineers are in business to design functional suspensions. It's not necessarily as simple as slapping on a four-link and going to town. We're not here to scare anyone out of doing things themselves, but rather, we want to delve deeper into educating our readers and cover something no one has ever shed any real light on: rear suspension setup.
Why so much talk about rear suspension? It seems these days no self-respecting mini-truck is show-worthy without having an attention-commanding "Goldberg device" (Google it) hanging out of a cavernous hole in the bed. Most rear suspension designs are limited to certain confines that don't create many severe effects, but there are major design considerations that should be taken into account. Regardless of how you lift the frame off of the rearend, the links that connect the rearend to the chassis are what affect the dynamic relationship of the vehicle to the road. Before we go into the actual suspension designs I think it would benefit us to define the effects.
Every suspension design has its benefits. Even the tried-and-true four-link has infinite design options to be an advantage in one area more than the other. The dynamics that are affected by the design, that are important to us here, are:
* Roll center
* Roll steer
* Pinion angle
Also, before we even discuss these we need to define instantaneous center, or instant center. Instant center is a theoretical point in space that is used to calculate suspension effect. The way to find instant center is easy once you "get it." When you have two or more bars, arms, or whatever you are working with, each part is only as long as a straight line drawn from pivot to pivot. If you were to extend the line drawn through those points into theoretical "space" and do the same through the pivots of the other related parts, hopefully, at some point, they would meet. The point at which they meet is the instant center. If this doesn't make any sense, keep thinking about it until it does. To continue reading without understanding instant center is not going to be as beneficial.