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Project Jeep Therapy: Frame Building
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By: Jeff Layton - 5/2000



Down to the Bare Frame
Bare frame
Old Crossmember cut off
Old cross member cut off
A beefy rear cross member
Thick new cross member
Cutting the xmember holes with a hole bit
Drilling holes for the body mounts. The plugs left over from the drilling were turned upside down and used to create spacers to level the nuts for the fuel tank mounting.
The new cross member mounted and drilled
Here you can see the finished cross-member. Note the big hole near the center - that’s for the trailer connector, and right next to it are the center supports for the super-duty tow bumper (featured in a future article). Smaller hole on far right is for air line.
Back of cross member
From the back of the cross-member you can see the nuts and spacers used to mount all the accessories, as well as the frame-rail tie-in brackets.
The air chisel could not cut it
Removing spring hangers with air chisel
Some big holes in the frame!
Big holes cut in frame
Heavy Duty Reinforcement with MORE and A Welder
Welding on the frame plates
Plates welded on
Welding on the frame plates

OK, if we’re going to get serious about this build-up, it’s time to dive in. All the big parts were already gone, but the frame still had the power steering box attached, as well as the many hoses and lines running along the frame. Strip it all off down to the bare frame and we’re ready to begin.

This is going to be one of those projects you could never sell to recoup your expenses…it’s destined to be kept forever, given to my grandkids when I’m too old to drive it anymore. To make the Jeep last 40+ more years of real hard offroading, building the frame right would provide a good foundation. My plans (see part 2) include a custom frame-mounted jamboree rack and frame-mounted tire carrier. These, combined with a custom tow-bumper and rear tow hooks would significantly over-stress the OEM rear cross-member. The factory stamped sheet metal piece had to go.

The factory piece was cut off in sections using an abrasive cutoff wheel, and the remaining welded sections were chiseled off the frame using an air chisel. A custom rear cross-member was fabricated out of a piece of 3" channel iron, notched to sit flush with the bottom of the frame, allowing spring shackle hangers to remain in their factory locations. Rounded tabs were welded to the cross-member to provide support for the rear body mounts. Check out the thickness of the new piece compared to the OEM piece.

Several other custom touches were added to the new "super-beef" rear cross member: High-strength steel (60 KSI) brackets were used to tie it into the frame and provide exceptional strength, nuts were welded to the back to provide easy bumper mounting, and holes were cut for both a trailer wire connector and for an air line to the custom rear air bumper (which was also used as a template for welding the mounting nuts and will be featured in a future article). Other small touches include smaller nuts welded to the back for easy mounting for the trailer connector and other nuts were welded to the inner bottom for easy mounting of the fuel tank. Because this is made from channel iron, the side pieces are tapered, causing the backs to need reverse-tapered spacers so the nuts for the fuel tank would be level. These spacers were made from the drops when the notches were cut.

The next piece of the frame that needed attention was the front spring area. Since a shackle-reversal kit was to be used, the front spring rear frame mounts had to come off. It’s harder than it looks - the air chisel in the picture didn’t do much damage. A small cutoff wheel saw a lot of use, then the air chisel finished it off. The OEM rivets holding these brackets on are much stronger than they look and needed a healthy dose of cutoff wheel to weaken them enough for the chisel.

The other section up front that needed attention was the frame-mounted spring shackle mounting nuts. These are welded into the frame by the factory to hold suspension and steering components, and with the help of some rust and torque, many of them had broken loose over the years. I had fished some nuts down there a couple years ago when I replaced the shackle hangers and it was time for a long-term fix. It takes some serious bravery (or stupidity) to cut big holes in your frame. Either way, I had enough of both!

Cutting these holes with a big hole saw is when you realize just how tough the factory frames are - this is not your average low-carbon steel! Each hole took me at least 10 minutes using a new hole saw, cutting oil, and a big ½" DeWalt power drill. Once the holes were cut, the nuts inside the frame were welded up and the cut-out sections were welded back in place. (The spring mounting nuts for the rear were welded inside the frame when the rear crossmember was off.)

With 2 big 2 ½" holes per side, my frame sure needed reinforcing, whether the holes were welded back up or not. A quick call to Chris Overacker at Mountain Off-Road Enterprises (M.O.R.E.) provided the frame reinforcing plates (among other super heavy-duty parts to be featured in future articles). Chris uses the plates to stiffen up the CJ frames and avoid stress-induced fatigue cracks; I needed them to make sure I didn’t add create any weaknesses when I was fixing others.

Some bolts were used to align the frame plates with factory holes; vise-grip welding clamps and c-clamps were used to hold the plates in place for welding. After tacking the plates in place, 1 ½" strap was used on the top of the frame, forming sort of an "angle-iron" when welded to the frame plates…this should be plenty strong enough. Any suspension travel lost through lost frame flex will be regained by a supple, compliant suspension. As with the rear cross-member, the frame plates were primed to prevent rust before the frame could be completely stripped and painted.

A couple small tricks not visible in the photos should be noted: first off, the small tubes that prevent the frame from being crushed when tightening down the winch mount bolts are now a little short with the added width of the frame plates. No problem - weld them in place, anchoring them to the frame plates. The welds were smoothed out with a die grinder so the bolts would once again pass through unrestricted. The second trick was corrosion protection. Both at the rear frame tie-in plates and the front frame reinforcing plates, the added material created a pocket that could collect moisture and cause rust. Since I’m after 40+ years of life from this project, I was careful to clean and coat the inner surfaces before welding with 3M Weld-Thru coating. A bodyman I know recommended it for just this application. At $14 a can, I sure hope it works!

When welding the frame plates to the frame, the front cross-member welds were also reinforced some. The bottom of the frame plates are tougher to weld, because you’re welding while laying on your back. If your frame is bare like mine was, you and a buddy can easily flip it over for easy welding. Grind your welds smooth to maintain an OEM appearance and you’re finished! Before we can acid dunk and paint the frame though, we’ll need to weld on the motor mounts and the supports for the air tank and extra gas tank, so it’ll be a few episodes before we get to that part. Next episode we’ll cover some custom axle prep and the search for a motor.

Sources

Mountain Off-Road Enterprises
Dept. ORN
P.O. Box 843
Rifle, CO 81650
(970) 625-0500


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