Ok, here goes my explanation of the uppers and lowers.


The lower control arms are mounted perpendicular(90*) to the axle.
The uppers are mounted about 20* (ballpark guess) off of perpendicular (so 110* and 70*).

The upper arms control where the axle goes during vertical movement that they also keep the axle centered under the car.

One of the biggest problems with the 4 link is bind. This happens because you have control arms (uppers and lowers) of different lengths affixed to the axle moving in different arcs as the axle moves up and down relative to the vehicle. The arcs cross at a point and are 'fairly' close to one another, but as you move further up (or down for that matter), the arcs deviate more. This causes bushing deflection and eventually bind (as the bushings run out of room to compress).

The bushing deflection and bind actually provide dampening (spring rate) in a very unpredictable manner and make the 4 link very difficult to dial in.

A panhard bar is designed to locate the axle under the car in a centered fashion as well, so when you put one in, you no longer need the uppers to locate the axle in that plane and can take them out entirely. The panhard bar has different geometry and mounts to the chassis in alternate locations and doesn't cause bind that the stock uppers do.


The torque arm controlls body roll. It's a steel bar that runs parallel to the driveshaft with brackets on each end. The front brackes mount to the tranny mounts (so the front of the bar is fixed). The rear brackes mount to the axle. The end result is that when the car rolls, the bar twists (tortion).

Hopefully that explains things for you a little bit zate.