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Simple CJ Frame Fix

by Terry L. Howe

Frame fix side

Many '76-'86 CJs you look at will be suffering some frame rust around the rear spring hanger. Eventually, this rust will become severe and the rear spring hanger will rip off, especially under hard use. Fixing this problem is not as hard or expensive as you might think.

The great thing about '76-'86 CJs is the fully boxed frame. The frame is the strongest frame ever used in a CJ, great for four wheeling. One problem with it is the part above the rear spring hanger tends to collect dirt and moisture and eventually rust out. You'll notice most CJs of this vintage have suffered some damage in this area.

After a trip to Lower Chinamen's Gulch, I noticed that familiar creaking sound when accelerating and braking that meant I'd cracked my frame and my spring hanger was about to rip off. I knew the sound because early in the year I ripped off a spring hanger after the Winter Meeting in Las Cruces. The fix I made last time was easy and cheap and it had survived a couple runs on Holy Cross and the trails of Moab. This time I decided to take some pictures.

The fix only requires access to a welder, circular hand saw, air cut off wheel, and drill. Instead of welding new metal to the frame, I bolted the repair to the frame using existing holes in the frame. The advantage of bolting the repair to the frame is there is no need to remove the gas tank or tub. Since I have an oversize gas tank, there was no way I was going to be able to weld on the repair without removing the tank. Making the repair without removing the tank saved me a day of work.

The following supplies were used to complete the project:

  • 2 - 1/2"x1" coarse grade 5 bolts with nuts
  • 2 - 5/8"x4" coarse grade 5 bolts with nuts and lock washers
  • Scrap of 3/16" plate

Remove rusted frame material Start by putting the rear end of the Jeep up on jack stands and removing the bolts holding on the spring hanger. As soon as I removed the spring hanger, I could see the crack running along the boxing weld and across the lower part of the outer channel. Using an air cut off wheel, cut the rest of the bottom piece of the channel and removed all the damaged material around the cracks. After removing the damaged material and cleaning it with a wire brush, spray it down with a rust converting primer.

While the primer was drying, cut three pieces of 3/16" plate. Cut two pieces 2 5/8" X 9" for the sides and cut one piece for the bottom 6" long and 3 1/4" wide tapering out to 5". I tappered the bottom piece so it was wide enough to use as a frame tie in with my bumper in the future.

Bolt on repair bracket Using a pair of vice grip clamps, clamp the inside plate and the bottom plate in place so that the bottom edge of the inside piece was flush with the bottom plate. Mark the inside piece with the two holes that already exist in the frame rail for drilling. Remove the inside plate and clamp on the outside plate so that the bottom edge of the plate is flush with the top of the bottom plate. Mark the outside plate for drilling and the bottom plate for the spring hanger.

Bolt on repair bracket Remove the plates, and drill the inside and outside plates with a 5/8" drill. One of the frame holes on the inside frame channel may also need to be enlarged to 5/8", the other three holes should already be 5/8". Drill the bottom plate with a 1/2" bit and bolt a spring hanger to the plate. Weld the nuts to the top of the bottom plate.

Once the drilling is complete, the hard work is done. Bolt the inside and outside plates in place and clamp on the bottom plate. Tack weld the three plates together and remove the whole thing. Complete the welding on the floor so you can get a good even bead. Since my exhaust routes out the corner, I also welded two 3/8"x1 1/2" bolts on the outside plate to act as a heavy duty exhaust hanger. Bolt everything back together and you are all done.

Frame fix side

Last modified Wednesday, 01-Dec-2010 09:18:28 MST

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