FabWorx Fullsize Chevy Solid Axle Four Link Kit - 4-Wheel & Off-Road Magazine

Fred Williams Brand Manager, Petersen’s 4Wheel & Off Road

FabWorx Offroad has a new solid-axle swap kit for ’01-’07 3⁄4- and 1-ton GM 4x4s that uses a four-link and track bar system to locate a solid Dana 60 where the torsion bars and A-arms used to live. This system incorporates coilover shocks for 10 to 12 inches of lift to clear massive tires (up to 40s, depending on wheel opening) . We recently upgraded our ’03 Avalanche to this setup and noticed improved ride right out of the shop. Using rebuildable 12-inch-travel, 21⁄2-inch-diameter Sway-A-Way shocks we can further fine-tune the suspension for greater high-speed control whether we’re heading to the desert for the weekend or across the barren wasteland should we encounter the zombie apocalypse in our flat-black monster truck.

linked And Sprung Solid 2003 Chevy Avalanche Front Suspension Photo 35628959

A solid-axle swap is a big undertaking, and even in the FabWorx shop it took a solid week of wrenching, cutting, grinding, and drilling before we bolted on the new suspension. The FabWorx kit is optimal for truck owners looking for a big tall truck that still needs to fulfill daily truck duty. FabWorx also offers leaf-spring solid-axle swap kits and is in the early stages of developing a lower-stance four-link solidaxle swap kit.

PhotosView Slideshow The most time-consuming portion of any solid-axle swap is removing the previous suspension and cleaning the frame. Our Avalanche had a leaf-sprung solid-axle kit but still required hours and hours of dust-inducing chopping and grindings from a plasma cutter and grinder. Like any masterpiece, starting with a clean slate is helpful, so grinding the frame smooth and welding any cracks, rust holes, or cuts flat creates a nicer starting point. The FabWorx kit is bolt-on but can also be welded on, so clean metal is important for strong welds. By weighing the sprung weight on our Longacre race scales, we could determine what coil spring rates to run on the Sway- A-Way coilover shocks. With rear tires on the ground the front weighed 3,400 pounds with winch bumper, 2,750 without. As reference, a Duramax crewcab Chevy in the shop had a front sprung weight of 3,370 with winch bumper. The FabWorx link suspension system uses a four-link with track bar. This design incorporates threaded 13⁄4x3⁄8-inch DOM tubular links. We ran massive EMF Heim joints at the axle end of the links, and bushings at the frame. These Canadia-made joints have a 11⁄4-inch shank and a high misalignment ball, which fits a 5⁄8-inch bolt. Made of billet 4140 chromoly, they are rated at 110,000-pound radial load and 44,000-pound axial load. The track bar utilizes Heim joints at both ends. These were EMF size small, 7⁄8-inch rod end with a 5⁄8-inch hole. The track bar keeps the axle from moving side to side beyond an inch or two during the arc of the suspension travel. The kit includes frame mounts for coilover shocks, a track bar, and links. All the brackets are made of 1⁄4-inch material, welded, and available raw, painted, or powdercoated. The link mounts tie the framerails together with a crossmember below the transmission and transfer case. The current kit drops the links below the framerail about 6 inches, but a flatter-belly kit is in development for trucks requiring less lift and more ground clearance. Welding is required for attaching the link mounts to the axlehousing. Our axle is a custom Dynatrac axle built to ’78-’79 Ford Dana 60 specs. The kit can also be used with other 3⁄4- or 1- ton front axles as long as the short side is wide enough to fit the link bracket. Axles will require a speed sensor to continue antilock braking system performance. The driver’s front frame bracket also incorporates the track bar mount, which ties into the original IFS third member hanger for additional strength. A drop pitman arm to parallel the draglink with the track bar is included with the steering upgrade option. Our 12-inch-travel Sway-A-Way coilover shocks are test-fitted in the upper shock towers, and then the lower mounts are tacked in place before being fully welded with the shocks removed. Caution must be taken when welding near shocks because spatter can damage their polished shafts and seals. We assembled the 21⁄2-inch-diameter shocks with the included dual-rate stop nuts set so that the distance from the bottom edge of the floater seat to the top of the lower spring seat is longer than the fully compressed length of the lower coil spring. This ensures that the spring doesn’t bottom out and damage the shock. Our coil springs came from Poly Performance, and we opted for a 12x3x450 over a 12x3x500. Our upper spring is 12 inches long, 3-inch ID, and 450 lb/in; the lower is identical but 500 lb/in. The combined spring rate is equal to the top rate times the bottom rate divided by the top rate plus the bottom rate CR = (TR x BR) diviede by (TR   BR). This gave us a combined rate of 237 lb/in. With approximately 3,200 pounds of sprung weight (including the new lighter winch bumper; more on that in a future issue), it should compress the 24 inches of coil spring approximately 7 inches per side (1,600 pounds per side divided by 236 spring rate = 6.77 inches), giving us 5 inches of compression and 7 inches of droop travel. When the upper coil compresses enough that the floater seat stops against the dual-rate stop nuts, the spring rate will jump from 236 to the heavier 500 of the lower coil to help slow the compression quickly. Adjusting these rates (putting the lighter coil on the bottom) can fine-tune the ride as needed. The FabWorx suspension will help control the axle rotating under load with the four links. Additional brackets can be added for a sway bar, Sway-A-Way bumpstops, and limiting straps as needed.

Low Leaf-er
Many solid-axle swap kits spring the trucks to the moon, which is great for deep mud or just looking like you like deep mud, but what if you want to delete all the IFS junk without jacking the truck sky-high? FabWorx co-owner Bryan McCully did some R&D to his ’98 Chevy shortbed to develop a solid-axle swap kit that would keep the truck close to stock height. He achieved a lift just 21⁄2 inches over stock that clears a 32-inch tire with ease by using a proprietary reverse-arch spring. He claims the ride is on par with the stock IFS, yet he feels the truck is much more robust. Even with a 3⁄4-ton Dana 44 he feels the front end will require less service and have fewer worn parts than the old independent front suspension.

linked And Sprung Solid 1998 Chevy 1500 Photo 40515129