RS-SK390EXTExtended Shackle Holden Colorado/ Isuzu DMAX 2012 and onVMN's extended shackles feature mounting holes for Holden Colorado and Isuzu DMA...$220.00
Extended shackles are a low cost method of increasing rear vehicle lift between 30-40mm, and they give you an extended range of travel with increased droop. In some circumstances they enable the installation of longer leaf springs, which brings better suspension.
A shackle is a very important part your suspension, connecting the leaf spring and the vehicle frame. It enables the leaf spring to operate through length changes as your suspension performs. The leaf packs, or leaf springs, are placed centrally under the axle of your vehicle.
Shackles also support your vehicle's weight, given they are the primary part of the suspension. As a leaf spring flexes, its distance from the main eye to shackle eye fluctuates. When you upgrade your suspension or use a lift kit, they will probably be supplied new shackles.
If you begin with factory fitted shackles, there are a number of factors affected when you extended the shackle... let's look at the pros and cons:
Yes. As a leaf spring compresses, it gets longer as the spring arc flattens. Then as the leaf spring relaxes, it gets shorter as the spring arc returns to its default position. It's the shackle which enables this motion to occur, and the adjusting length very much impacts the total spring movement.
An extended shackle enables the spring to drop farther down while in its default position. It may also enable the spring to flatten more as it compresses... however this can be limited by the frame side mount or a rear crossmember. As it compresses, the shackle will be going away from the axle.