Well-Known Member
I know the subject has been broached a few times, but in my time here I've never seen it really covered. So I thot I'd see where this takes us.

My thinking is this, & it is quite probable that I'm wrong, but if you set the angle of the shackle at ride height such that as the spring compress' the shackle eyelet moves upwards relative to the the frame then you have decreasing spring rate. You are essentially getting more verticle movement of the axle than the spring is deflecting. So a 100 lbs/in spring might actually move 1.1" for that 100 lbs, thus making it effectively a ~90 lbs/in spring. Yet this is how I see most shackles set up. I'm guessing I'm missing something very obvious here.

My second Q is tension shackle or compression shackle ? From a metals point of view the tension shackle makes more sense. The shackle wouldn't have to be as burly as a compression shackle, yet it could still have a reasonable lifespan. Seems like that is not the prefered set-up, why ?


I used swerve around my halucinations, now I drive right thru them.