shackle movement?

[1936coupe]

suspension shackles sit at approx 40/45 degrees, what degree movement under normal driving would you expect from the shackles with rubber bushed shackle bolts? does the rubber bonding stop movement? the plastic sleeved shackles/bolts can move as much as is needed? just trying to understand the mechanics of it. thanks.

 

[joel]

I have used the plastic bushings and they allow the shackle to rotate easily and the spring to stretch and contract quicker. I think this gives a "plusher" ride, but requires shocks to dampen movement; other wise the ride is "bouncy" JMO