Shackles are components of leaf spring suspension systems for trucks, cars, vans, and SUVs. They play an essential role in ensuring that the leaf will handle length changes correctly. They can be found between the spring and the hanger, which is connected to the frame to facilitate movement. The other end of the leaf spring stays mounted to the chassis. It may become necessary to replace shackles when they begin to function improperly.
OEM shackles will not last forever. Over time, they can become worn, rusted, or they may break apart. This will cause undesired movement, and it will affect the handling of the vehicle. When shackles become worn, they should be replaced to avoid possible dangerous situations on the road. Installing new shackles will also create a more stable and secure ride.
Shackles perform a necessary function for every vehicle with leaf spring suspension. Without the shackles' help, the leaf spring wouldn't be able to flex. If the vehicle should hit a bump, this would cause a problem. The tire would quickly lose contact with the road's surface instead having the ability to adapt and remain steady.
When replacing shackles, there are several considerations that should be made. For example, whether one purchases longer or shorter shackles can have its benefits. Longer shackles allow for greater lift and a substantial amount of ground clearance. Choosing shorter shackles will function as a lowering shackle.
Instructions for Installation of New Shackles
If there is some concern over installing shackles incorrectly, these instructions can make it easy. Simply follow these directions to correctly install new shackles.
Changing leaf spring shackles will require some basic hand tools.
• Jack Stands
• SAE or Metric socket set
1. Lower the jack. Allow the suspension to droop so that it will take the weight of the vehicle off of the shackle. This will keep the shackle from binding, and it facilitates the removal of the mounting bolts.
2. Disconnect the lower mounting bolt from the shackle and the spring by using a socket and ratchet. Lower the axle so that the spring drops completely out of the shackle.
3. Remove the mounting bolt, and remove the shackle from the frame. If the bolt has been on there for a long time, it may be necessary to use a dead blow hammer to force it to become loose.
4. Position the new shackle on the frame. Insert the mounting bolt, and allow the bolt to remain loose. Later, the shackle can be moved around to help align both the shackle and spring.
5. Lift the rear axle by using the jack. Align the spring eye with the shackle. Slowly insert the spring into the shackle. Raise the jack a little at a time just until the holes on the shackle and the spring eye line up.
6. Install the mounting bolt directly through the shackle and the spring. Tighten the bolts by using a ratchet and socket.
Use the jack to both raise and lower the axle while lining up the spring eye with the shackle. It will prevent unnecessary strain on the back.
Things to Consider Before Choosing to Increase Shackle Length
Many vehicle owners believe that increasing the shackle length on their vehicles would be beneficial; however, there are several things that will happen when a vehicle's shackle length is changed. A longer shackle will move one end of the leaf spring away from the frame, which will cause several things to occur. Consider the following occurrences before choosing longer shackles.
• It will rotate the axle down at the shackle side of the spring.
• It will decrease the castor angle of the front axle affecting steering stability at high speeds, and it will also reduce the steering’s ability to return to the center after making a turn.
• It will increase the pinion angle.
• It will increase leverage on the shackle mount.
• It will increase the droop-down travel.
• It will decrease the approach/departure angle.