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Motobilt Tech: "Jeep Back Half Kit"

What is a back half kit from Motobilt? A Motobilt back half kit allows you to cut off the back portion of your frame and replace it with 7 different steel fabricated pieces. The kit is available for the Jeep TJ here , the Jeep YJ here. and now the Jeep LJ here.


Why would I want a Motobilt back half kit? If you are planning on performing a custom link suspension in the back of your Jeep, then a back half kit will give you the extra clearance needed for all of the components to fit. When fabricating or installing a link suspension in the back of your Jeep, you are most likely going to be stretching the wheel base and moving the axle back. When doing this you will soon find out that your stock frame is in the way. You can see in the following picture how the frame rises up from the skid plate but then towards the end drops back down. This is what causes the most trouble when trying to fit a custom suspension and stretch the wheelbase.

Also, there is not a lot of room between the stock frame rails and the inside of your tires. Building custom four link suspension on a Jeep YJ, TJ, or LJ does not have to be difficult. The Motobilt Jeep back half kits are an effective way to gain clearance for suspension components like coil overs shocks, bypass shocks, or ORI struts. The Jeep Back Half Kit moves the frame rails to the bottom side of the tube. The frame rails will mount directly to the bottom side of the rear floor board for a tight compact fit. It should be noted the kit requires cutting sheet metal on the body just below the tailgate to allow the frame rails to extend out. The bumper is then attached in this new location. The Motobilt kit comes complete with a rear bumper.

Unlike some of the other kits on the market we do not require you to purchase square tubing to complete the project. With that said we provide a flat point on the back center of the rear bumper for the installer to triangulate some round tubing if required. .

What else do I need to do when installing a Motobilt Back half kit? The installation requires that the body remain on the frame of the Jeep. We have body mount tabs located on the long straight sections of the frame that will mount to the factory cross member mounts of the Jeep tub. These will be used as a reference point on where to cut your frame.


Here you can see the body mount tab and how it attaches to the tub.

Once you have measured and made your cut it will look similar to this.

How much you have to cut for the rear frame rail to pass through will depend on if you have a body lift or not. It will work with or without a body lift. You will need to relocate your fuel tank. For the Jeep YJ, we offer a new fuel cell.

If you have a Jeep TJ you can run the Motobilt MB5005-TJ fuel cell and use the Motobilt fuel cell mount.

There are many things you will need to do to modify your Jeep and we will try and cover those areas in a future Tech Thursday article. Be sure to check out our Link suspension section and Fox shocks also!
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