Full Reverse and two-Forward/two-Reverse Link Systems
If all you're looking for is simplicity of installation and you don't want a two-link, these systems are the ticket. We have all seen them at shows or on the road (you might even own one!), so we can't argue that they don't work. The best explanation that we've been able to come up with for these systems is that they are counterproductive. The suspension's job is to take energy that is being transferred into the tires from the ground and to properly transmit those forces into the chassis to be used to create more traction. A reverse link system, in which the bars mount to the rear axle and the rear of the chassis behind it, does just the opposite, and the two-forward/two-reverse link system is nearly unpredictable in how it transfers energy from the ground to the chassis.
Even if you calculate every single point to an exact placement when designing one of these systems for your truck, you will still only end up with a driveable truck and not one that handles properly. Your only hope for performance with a reverse triangulated four-link is to limit the travel as much as possible and run a stiff spring and a stiff shock. Then, maybe you'll have the traction of a poorly set-up forward-facing link system. The best way to think about it is to understand that with a properly designed forward-link system the rearend is actually being pushed against the ground by the chassis. So any force that the rearend can use to push against the chassis will ultimately create more traction. With a reverse-link system, if the rearend were to pull down on the chassis there would be an equal loss of traction. Try this on a bathroom scale. Stand on the scale in front of a cabinet and pull up on the cabinet and see that your weight goes up according to how much force you are able to apply to the cabinet. Now push down on the cabinet. Your weight will go down to nothing fairly easily. That is what's happening on a reverse-link system. The rotating force of the tires driving the truck forward applies an opposite twisting force into the rearend housing, and that force is applied to the chassis behind the rearend pulling the back of the chassis down, thus negating any hope for traction.
On paper, this design looks great because the pinion can be kept well within working limits. A quite desirable instant center can be calculated, and it seems to fit into the confines of just about any truck. The real negative effects are all dynamic, meaning that they are only noticeable when the truck is being driven and the more dynamics being applied, the less traction it has.
FIGURE 2
You can see from these diagrams that the pinion angle moves in a peculiar way (Figure 2). U-joints don't like the angles that are generated by a two-forward/two-reverse link system. It is possible to make the system work for a daily driver with zero performance advantages, but only with limited travel. On a two-forward/two-reverse system there are so many variables that can cause undesirable dynamic effects. The pinion is quite hard to keep within reasonable working limits, and the instant center moves around so much that there is no way for a normal human to track it, so calculating how forces are transmitted into the chassis is nearly impossible. It probably has more negatives than any other link design.