ok so my plan is to make a 1/4 elliptical rear spring suspension I plan to use the lower springs as the lower parts of a 4 bar and the upper would be triangular .. so i dont have to use a panard my question is how much pinion angle change can i take because as the car is loaded w weight the spring will length turning the pinion angle down ... as the car accelerates the pinion angle will go UP ...
If you set it up like a four link, you shouldn't have a change in pinion angle. thats the whole purpose of a four link. At ride height your spring length should be equal to the length of the upper link.
I have an Austin Healey Sprite that from the factory uses 1/4 leaf, and an upper link. In this setup, the upper control arm is basically the same length as the spring, so there is little pinion change. It also is not triangulated. Since the spring pack is fixed at the forward point, side to side movement is limited. However for "spirited" driving a panhard bar or watts link is recomended.
You need to get loaded weight on the spring (2 fat chicks is about right) and measure straight (not along the arch) from the center bolt to the eye. Also the height difference from the eye hole to the spring at the center bolt. That will be the angle and length to set up the upper links to keep everything parallel and cut down on pinion angle change
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