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Long Travel LeavesRevamp Your Leaf-Spring Suspension From the February, 2009 issue of 4Wheel & Off-Road By Jerrod Jones Photography by Jerrod Jones
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Leaf-spring suspensions have been around forever, and there are tweaks you can do to make one spring work differently than another. You can taper the ends, use smaller leaves, use overloads, make bigger arches, relocate spring eyes, and so on. All of these things make leaf springs ride differently. But what about using longer leaves to absorb the vehicle's suspension force over a longer leverage arm? What is entailed in this sort of modification? Obviously, one spring hanger has to be moved. But what else? Remember that nothing is ever as easy as it sounds, and we definitely ran across that old clich again with this suspension build. As far as custom suspensions go, this was a fairly simple project that you too could build at home with a welder. We used a '75 Blazer with a bolt-on 6-inch lift, a block-lifted rear, and some blown-out shocks as a test dummy and recipient of a new, much more supple suspension. The plan was to make a slinky suspension that we could crawl and twist the K5 with, while still being able to jam down a stretch of dirt road or through the dunes at high speeds. We started the buildup with a set of 7-inch-longer Deaver front leaf packs, 14-inch-travel Bilstein 7100-series remote-reservoir shocks, Energy Suspension bumpstops, 11-pack rear leaves, and an Off-Road Design shackle flip. By the end of the project, we had also added new centerpins, a driveshaft, bronze shims, and Off-Road Design's 1-inch zero-rate add-a-leaf to the list. Follow along as we start the buildup and address any issues as they arise.  When we ordered the front...  When we ordered the front leaf packs, we were unsure how to properly mount them, as the new springs place the shackle directly below the body mount. A quick call to Deaver led us to Baja Shop in Orange, California, to assist us in mounting the new front Deaver leaf packs. They had performed this long-spring conversion before, so were familiar with the shackle placement. Sure enough, Miguel Medina and Shawn Clark made a 1 3/4-inch hole for a bushing to mount the shackle directly under the body mount.  Shawn Clark went to work making...  Shawn Clark went to work making custom shackles that were 2 inches longer than the originals. He used 3/8-inch cold-rolled plate cut into 8-inch-long straps. The longer length will allow the leaf springs to flatten out to a longer length than a shorter shackle would, and will also allow more droop.  The Deaver long leaves measure...  The Deaver long leaves measure out to 51 1/2 inches unweighted, while the old stock-length leaves measure out to 44 1/2 inches unweighted. The 7-inch-longer leaves will allow for more suspension travel and a smoother ride, as the force upon the spring is now distributed over a longer leverage arm (the longer leaf).  The new shackle mount is 5...  The new shackle mount is 5 inches farther back than the original on the frame and mounts directly under the body mount. We placed an Energy Suspension bushing into the 1 3/4-inch hole and ran a 9/16-inch bolt through the shackle and bushing. Once together, we found that the front axle was moved forward about 1 1/2 inches. And though a longer wheelbase is usually a benefit, it might create some steering linkage and sway bar issues, depending on whatcha got under your rig. In our case, the crossover steering was not an issue, and we had no sway bar to deal with.  With the front leaves mounted,...  With the front leaves mounted, we finished the rest of the suspension and fine tuning at Advance Automotive in Torrance, California. Jim Pierce started by using 1 3/4-inch, 0.120-wall tubing to make some front shock hoops to fit the 14-inch-stroke Bilsteins. The frame was plated where the hoops attach to better distribute the load over a larger surface area, and we used a connecting crossmember between the two hoops to help support the load.  Eric Swenston mocked up where...  Eric Swenston mocked up where the dual front 14-inch stroke Bilstein 7100-series shocks would go, and then bolted the shock spacers and mounts together before tack-welding them into place on the shock hoop. This gives us a chance to double-check and make sure everything lines up before making any final welds into place.
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