4x4 Truck Leaf Springs - Willie's WorkbenchPosted in How To: Tech Qa on April 1, 2002 0) (
Leaf springs are pretty common on custom 4x4s, even though coil and coilover combinations are becoming quite popular. Coils and coilovers can be tempting, but don't sell the old-fashioned leaf-spring design short. Leaf springs are simple in design, and, in most instances, don't require multi-link accessory bars, as they locate and stabilize the axle, as well as support the vehicle. With the proper spring rates, shackle bushings, and shackles, they will let a vehicle articulate quite well. In addition, unlike coil springs, the lift and spring rate can easily be modified to suit a particular need, be it height, ride quality, or load capacity, by adding or subtracting leafs or by changing the arch of the spring pack.
For instance, I'm building a modified, extended-wheelbase flatfender Jeep and for the above-cited reasons, decided to stay with a leaf-spring suspension system. My springs of choice originally were used on the rear of the '84-'01 Jeep Cherokee. These 2 1/2-inch-wide springs are a bit different in that the locating pin is not centered in the spring, but instead is offset, giving the front section an approximate length of 23 inches versus the rear section's longer 28.5 inches. This unequal length greatly reduces any tendency for the springs to wrap-up under hard acceleration and cause wheelhop.
Because this Jeep will carry about equal weight front to rear, I'm going to use exactly the same springs at both the front and rear. The short side will be toward the front at the frontend and toward the rear at the rearend to maintain maximum approach and departure angles.
These stock Cherokee springs still weren't exactly what I wanted or needed, however, nor did the aftermarket provide what I needed. Because price is as important to me as it is to you, using basic off-the-shelf components in case there is an immediate need for replacement also is a priority. Being impressed with the quality and soft ride of Skyjacker's new line of leaf springs, I ordered four 2 1/2-inch-lift rear Cherokee springs. To maintain original ride quality, these springs use three matched arched leaves with nylon slip pads and a large flat leaf to handle extra loads.
I disassembled the spring pack and discarded the flat leaf because my Jeep load was to be pretty constant. In its place I used a modified short-bottom leaf from a stock OEM Cherokee's spring pack. Modified how? In each end I drilled a 35/64-inch hole to accept the slip pads from the original Jeep spring pack's second leaf. Contrary to common belief, leaf springs can be drilled using a quality bit and cutting oil.
I wanted a No. 2 leaf to support the spring eyes on each end, so had a local spring shop make me up a leaf with a matching arch and ends that extended and slightly wrapped around the main spring eye. Removing the spacer on the Skyjacker spring clamps provided sufficient clearance for the additional new spring leaf. Even the original Skyjacker center bolt was reused.
Now I have a custom spring pack tailored to my particular needs at minimum expense and maximum replaceability if the need should arise.