78 Jeep CJ-5 Frame Replacement – Part 1

The jeepfan.com 1978 CJ-5 has almost no original major parts left on it except the frame, grill, and hood. There has always been little rust concerns for me since the Jeep stays in a garage and the body is fiberglass. Recently concerns for the frame’s well being have been growing. In the section under the driver’s seat the frame has completely split where the inner and outer section are joined. I have also noticed other places showing rust signs too.

The task of changing out a frame is no small one, it’s essentially a matter of disassembling the entire Jeep and reassembling it.

the donor

disassemble away!

rolling chassis

not much left

I contemplated a new aftermarket frame but the price was out of my budget. I located a donor Jeep, a 78 CJ-5 with a pathetic body and a dead engine but a good frame. I new I’d have some work to do to get the donor frame into good condition but I was up for the task. I also decided to coat the frame with POR-15 to keep the rust away.

The disassembly of the donor Jeep was easy: cut, wrench, destroy. The old rusty body was almost crumbling on contact.

The Repair

After the donor frame was freed of its parts it soon became evident that the rear frame ends where the rear cross member is attached was in need of some restoration. I cut away the sections using an angle grinder. It was at this point I decided to fabricate a new rear cross member that was cleaner looking than a factory Jeep one.

After all the rotted sections were removed the frame was washed thoroughly to remove grease and oil. I then took to the frame with a wire wheel on an angle grinder removing all the loose rust flakes and chunks. With the frame clean and free of loose rust I could clearly see the rest of the areas in need of repair.

cleaned frame
needs repair

I was going to use 3/8 in steel plates to fabricate and weld in plates to patch the areas along the frame rails and 2 inch square tube to restore the rear inner frame sections. I also needed to fix the body mount pads since the holes had rusted completely open.

I used a 2.5 inch piece of 3/8 c-channel steel to fabricate a new rear cross member. I closed the ends to make it look nice. Holes were drilled in the new rear cross member in the factory location so that I could add a rock type bumper to mount the spare tire carrier to.

Frame Restoration Gallery

bare frame – front view

bare frame – rear view

driver side inside rear

more rust

drivers side center

passenger side center



rear inner

rear inner

fixed body mount


Jeep Disassembly

I waited until the donor frame was finished to start disassembling my Jeep. I took lots of pictures so I could remember how to put everything back together. I made a list of things I wanted to do while the body was off.

* New side rocker guards attached to the frame.
* Connect roll bar to the frame
* New Olympic rear rock bumper with a 2 inch receiver, adapt my custom tire carrier to it.
* New high-performance single exhaust.
* Ditch the headers and duals.

Next – Part 2 – Rocker Guards, Roll Bar Mounts, Reassemble