FREE UP YOUR SPRINGS

Stock length shackles sometimes cause aftermarket springs to bind and not move or cycle smoothly.

- Christian Sturtz

The CJ3A we’ve been working on had stock “C” type shackles with metal to metal contact on both the inside of the leaf springs and the inside of the hangers, which can cause binding. The short length also limits the amount of motion the spring has. The shackle pulls on the hanger under compression and doesn’t pivot the shackle, which also happens on droop. (Figure 1)

When changing the shackle length, you have to look at several things before changing them out. Are the shocks going to work? A longer shackle changes the ride height. Sometimes a longer shackle will lower the ride height depending on the shackle hangers’ design and positioning. On this CJ-3A, the longer shackles will raise the ride height. We need to verify the shocks are long enough and still have enough travel that they will not bottom out at full compression.

The second thing to check is proper height bump stops. The bump stops need to be long/high enough that they don’t allow the spring to go into a negative arch or, if so, very little. Cycling a leaf spring into a negative arch dramatically reduces the life of the spring and can cause fatigue, as well as breaking.