Carli Suspension Shackle | 05+ F-350
Some of the jarring ride of the Super Duty rear can be attributed to the factory vulcanized bushings in the leaf spring pack and shackle. The factory shackle is very strong BUT the design is not conducive to a smooth ride. This is no surprise as a Super Duty isn’t made to ride well, it’s made to tow. The Factory leaf springs are high-spring-rate and short-travel, why would Ford design a shackle that rides well and is capable of extended suspension travel? Vulcanized bushings are a press-fit bushing often utilized by OEMs in which the bushing material is adhered on both points of contact.
 
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