Rear shackle angle

68gtxman said
The top of my head says 90 degrees to the frame, as it needs to move equally in both forward and reverse directions. Best to look at the FSM for sure.

no it dosn't as when it comes forward it unloads the tires. Best to have it at a 45* or flatter depending on how rough your roads are. My car seemed to launch best with them at a 30* angle or so but were hitting the frame spacers on bad bumps