The factory Jeep LJ rear frame was never designed for long wheelbase, coilover suspension builds. The frame rails sit inside the body, behind the axle, and limit how far you can move the axle rearward. This creates problems with wheelbase stretch, suspension geometry, and departure angle.
Once you start trying to run larger tires and a true four link suspension, the factory frame becomes the restriction.
A back half kit solves this by completely replacing that rear section of the frame.
The Motobilt Jeep LJ back half kit removes the factory rear frame rails and replaces them with a new structure designed to allow proper wheelbase stretch and suspension layout. By cutting off the factory frame and installing this system, you can move the rear axle rearward to match your build goals while keeping the chassis structure clean and functional.
The new frame rails are repositioned from inside the body to underneath it and tied directly into the bottom of the rear floor. This change opens up the entire rear of the chassis for proper link placement and coilover packaging. Instead of working around the factory layout, you are now building the suspension around a structure designed for it.
This is what allows a Jeep LJ to run longer wheelbase setups, larger tires, and proper four link geometry without compromise.
At the same time, the bumper is relocated up just below the tailgate. This reduces rear overhang and improves departure angle, which becomes more important as the wheelbase increases and the vehicle is used on steeper obstacles.
The system is designed for real fabrication. The upper and lower frame rail sections are joined during mockup so you can position everything based on your desired wheelbase and axle location. This gives you the flexibility to build the Jeep the way you want instead of being locked into a fixed layout.
The included 50 inch stubby rear bumper is built from formed plate and features 3/4 inch thick d-ring mounts that pass through the bumper and weld on both sides for strength. The structure is designed to work as part of the chassis, not just bolt onto it.
This kit is for builders who are stretching wheelbase, running coilovers, and building a Jeep LJ that performs correctly on the trail and holds up to real use.
