Springs......

[Mike K]

I confess , I am no authority here . But , normally at rest , the shackles are angled slightly towards the rear, e.g. past the vertical , about 15-20 degrees . As the springs change shape e.g. driving with a load and flex, the shackle angle increases .

If your shackles are vertical at rest , usually, this indicates that the springs have been set too high .

Again , this is only my casual observation and is not a definitive reply . It would vary from model to model depending on what type of design it is .

Mike