Suspension or brakes

[Doug Wilson]

Yesterday I noticed what sounded like my left rear brake dragging when taking off from a stop. When I got home I felt the rear wheel and it was very warm, not hot. This AM I pulled both back wheels and found a part that had come loose off of both wheel hubs. The part in question is a flat arm about a foot long that goes towards the back of the car and connects to a rod about 3/4" diameter that runs behind the rear axle up on the frame and goes across the car to the other side. Both ends connect to the back of the wheel hub (one on each side of the car) with a sort of eye bolt. The eye bolt connects to the lower inside front of the wheel and has a sort of swivel there that appears to do nothing else. I find nothing else connected to this rod and can move it by hand, since it is no longer connected to the hub where it is suppose to be connected. What is this rod and what does it do? Does it have anything to do with the brakes? I feel I still have a brake problem because it does smell bad and there is considerable amount of brake dust on the wheel and tire. The car is a 1975 450SL.
Thanks for any info as I can find a picture of what this is in my Chilton book, however no mention of it.
Thanks
Doug