Noob Alert: How does a Panhard bar work?

Hey guys, I am trying to figure out why I need an adjustable Panhard Rod. I'm not exactly sure how this stuff works on the suspension, could someone enlighten me on how the Panhard rod works? Or more general, how our rear suspension works? I tried howstuffworks.com, but they have only general specifications.

Sorry for the noob alert.

the rear end is held top the car at 4 points. one upper mount, two lower, and the panhard. the panhard bar keeps the rear end centered under the car. it runs the same direction as your axles. if you lengthen or shorten that bar, it moves your rear end side to side in relationship to the car. if you lower the car, the fixed bar moves in an arc shape. as it gets lower, that in turn pushes the rear end toward the drivers side. to correct the problem, you get an adjustable panhard bar to re-center the rear end under the car. the panhard bars only function is to locate the rear end under the car.

the two lower control arms mount the rear end forward and backward in relationship to the car. they take most of the abuse from the suspension. the upper arm attatches the top of the rear end to the car as well. you can adjust the pinion angle of the rear end with the upper control arm (if equipped with an aftermarket adjustable arm).

now the how it works part. if you imagine the angles of the upper control arm and the lower control arm extending towards the fron of the car they will intersect at a given point. this point is called the "instant center". this is the point that your car transfers the weight during driving (launching). with control arm relocation brackets, you can adjust the angle of the lower arms. this will change the instersection point of the control arm angles with the upper mount. if the arms are angled too narrow, they will intersect at the fron of the car, and wont transfer much weight to the rear wheels. if they are angle to intersect too far towards the rear, you wont get the proper weight transfer. you have to adjust to find the "sweet spot" for the best launch at the drag strip. i will see if i can find some pics of this, or i make use paint to make some for better clarity.

here is a good link for the basic live rear axle setups.

http://www.automotivearticles.com/Suspension_Design_2.shtml

Awesome bigcat, thank you very much.

In laymans terms, keeps the rear end where it should be under hard launches and cornering.