1979-87 Super Record derailleur.
 

Hi All,

Some time in the early '80s the spring arrangement in the Super Record rear derailleur was changed. The parallelogram spring was moved from the top to the bottom and the separate spring bolt dispensed with. Does anybody know why? Advantages of one over the other?

see VeloBase for your answer

Well, sorta, it doesn't really give you a reason why

Not sure of the reason, perhaps cost savings, or made for quicker assembly. My 86 S.R. rear derailleur operates smoothly as long as the shifter holds it in position so I have no complaints with the later generation version.