Compatible With:
YJ
The factory Jeep YJ frame is designed around the original rear axle location. It uses a raised section over the axle to allow upward suspension travel, then drops down behind the axle toward the rear bumper. This works in a stock configuration, but it becomes a limitation when the rear axle is moved backward to stretch the wheelbase.
Once the axle is relocated rearward, it is no longer positioned under the raised portion of the frame. Instead, it sits under the lower section of the frame rails. In this position, the axle will contact the frame during compression, limiting up travel and preventing the suspension from working correctly. The only way to compensate with a factory frame is to raise the vehicle significantly, which reduces stability.
A back half kit solves this problem by replacing the rear portion of the frame and keeping the frame rails high and consistent behind the axle instead of dropping down like the factory design.
The Motobilt YJ Back Half Stretch Kit builds on that concept by not only replacing the rear frame, but also extending it approximately 15 inches. This allows the rear axle to be moved further back while maintaining proper suspension travel without increasing ride height.
By keeping the frame rails high and narrowing the rear structure, this system creates the space needed to mount coilovers outside the frame and build a longer rear suspension system. The added wheelbase improves stability, increases traction, and allows better suspension geometry in technical terrain.
This system was also designed to allow a full conversion from a standard YJ to an LJ length body. The extended frame provides the foundation needed to stretch the body to match the longer wheelbase.
To complete the body conversion, this kit works with the following Motobilt components:
These components were designed to work together so builders can convert a traditional Jeep YJ into an LJ length body with consistent fitment across the chassis and body.
This exact combination of components was used on the Motobilt El Jefe build. Many builders will recognize that vehicle, and this system reflects the same approach used on that project.
This is not a repair section. It is a rear chassis and stretch system designed for advanced builds where wheelbase, suspension layout, and chassis geometry are all being corrected together.
To properly convert a Jeep YJ to LJ-length wheelbase, the following components are required:
These components work together to extend the chassis, body, and wheel opening location to properly match a 15 inch wheelbase stretch.
Want To Know More?
Find all the information you need to get the right part for your rig.
Which Rear Back Half Kit Do I Need?
Choosing the correct rear back half kit depends on your Jeep platform and whether you are keeping factory frame length or converting to LJ length.
Vehicle Fitment
1987–1995 Jeep Wrangler YJ
Material
3/16 inch Steel Plate
Frame Extension
Approximately 15 inches
Frame Width
8-1/16 inch narrower than factory YJ frame
Includes
Four frame rail sections
Integrated rear bumper
Reinforcement side plates
Weight
Approximately 75 lbs
Manufactured
Made in the USA
What does a back half kit do on a Jeep YJ?
It replaces and extends the rear portion of the frame so the rear axle can be moved back while maintaining proper suspension travel and geometry.
Why is a back half required for wheelbase stretch?
The factory frame only provides clearance at the original axle location. Once the axle is moved rearward, it sits under the lower portion of the frame and will contact it during compression. A back half keeps the frame rails high so the suspension can cycle correctly.
How is this different from a standard YJ back half kit?
A standard back half like MB3001 keeps the factory frame length. This kit extends the frame approximately 15 inches, creating a longer wheelbase and additional room for suspension and chassis layout.
Does this convert my YJ to LJ length?
This kit creates an LJ-length frame by extending the rear 15"s. To fully match an LJ-length body, additional Motobilt stretch body components are required.
What do I need to complete the YJ to LJ body conversion?
This frame kit works with Motobilt stretch components including corner armor, rocker guards or boat sides, inner fenders, and a stretch floor panel to extend the body to match the new frame length.
Why would I want to stretch my YJ wheelbase?
A longer wheelbase improves stability, especially in rock crawling, and a longer wheelbase performs better are steep climbs.
Can I run coilovers with this kit?
Yes. This kit is designed to create the space needed to mount coilovers outboard of the frame and build a longer rear suspension system.
Is this a replacement for a rusted frame?
No. This is not a repair section. It is designed for full chassis builds where the rear frame is being replaced and extended.
Does this include everything needed to stretch the body?
No. This kit only includes the frame components. The body must be cut and extended separately using additional parts.
Is this a bolt-on kit?
No. This is an advanced fabrication system that requires cutting, fitting, and welding.
Can this be used with other Motobilt frame components?
Yes. This kit can be used with the Motobilt front half and mid frame sections to build a complete frame system.
Is this the same setup used on the El Jefe build?
Yes. This stretch system and matching body components were used on the Motobilt El Jefe build.
Motobilt offers industry leading, American-made off-road parts, focusing on quality and precision. Every product is built in-house, ensuring reliable performance for your adventures. Let us be your go-to source for industry leading, top-notch gear and support in your off-road journey.
Phone: 334-219-2333
Email: info@motobilt.com
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