HD Rear Super Shackles with Greasable Rear Spring Bushings for GM Trucks
After seeing some thrashed rear shackles, we decided a beefier system was in order. These are folded and fully welded 1/4" steel with a .250 wall tube. The back gusset is extended down the spring mounting "ears" to keep them from bending. We also build them in different lengths for custom suspension applications.
The "short" length is 4.5" center to center which is the same as a '88-'98 GM and 1/2" longer than a '67-'87 GM trucks.
These shackle works on any GM or other vehicle with 2.5" wide springs and spring hangers in either tension or compression shackle applications.
Install these HD rear shackles with the open side to the front to prevent contact with the main leaf of the spring.
With deeper arch springs (6" or more lift) use the longer shackles and a shorter shackle flip. An example would be a 12" total lift would use the 2.5" shackle flip, a 6" HD rear shackle and the 8" lift spring. The longer shackle length helps keep the shackle from inverting to the front or back. There's nothing wrong with the 2.5" flip / 6" HD shackle combo for shorter lifts either but it's essential for taller springs.
Using stock length shackles with deep arch springs and a shackle flip can allow the shackles to flip the wrong direction, the fix is our longer 6" shackles. The longer shackles keep the shackle from flipping forward and allow the spring to compress and stretch out naturally under the weight of the truck.
Looking to add our Kevlar bushings to your leaf springs but don't know your spring eye ID? Here is a quick way to find out without pulling apart your truck.
Measure the OD of the spring eye,
in this case 2"
Then measure the thickness of the leaf 1/4" on this truck.
Now subtract 2 Xs the thickness from the spring eye OD
2 x .25 = .5
2" - .5" = 1.5"
So this spring needs 1.5" bushings.
*Make sure to do this on each spring eye because they can be different
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