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Saturday, November 20, 2010

Frame rail repair

Another good, solid few days of work on the Boss.  This weekend, I decided to tackle the repair of the left frame rail damage where the P/S bracket was ripped from it's mounts and a jack-wagon repair was attempted (more than once) at some point in the past.  In earlier postings, I show the damage and remnants of the repairs, so have a look to get a good idea as to the extent of damage.

I started off by fabricating the upper frame lip section.  This was the smallest piece that was required but it also acts as a sort-of "guide" to the rest of the job.  Using a clean sheet of 14 gage cold rolled steel, I transferred the pattern from the frame to the material and cut the patch slightly oversize on my band saw.  Now that the piece was a very manageable size, I slowly worked the edges with files, belt sander and angle grinder until the fit was just right.  I then clamped it up with locking pliers and tacked it into place with the MIG.  With it tacked up, I worked the shape just a little with a hammer and dolly to make sure the proper curvature was achieved.  Once I was satisfied with that, I stitched the patch in place starting from the inside out.  This essentially means the seam is fully welded from each side, ensuring complete penetration and a very strong repair.  Once welded, I ground all the welds down and prepared to fabricate the large lower patch.

In similar fashion to the lip patch, I traced the shape of the required patch on the sheet steel and cut it out a bit oversize to allow working stock.  I massaged the edges as above until the fit was just right then drilled plug weld holes along the outer edge.  After a quick trip through the blast cabinet, I treated the underside of the patch with weld-thru primer and let it dry while I had lunch (and sold a pair of Lincoln Versailles disc brake rear axles at the same time too!).  Once the primer was dry, it was time to tack in the lower patch.  Because this patch has a compound curve to it, I tacked the panel in from the end and slowly worked my way around, tweaking the alignment of the patch as I placed each tack.  This allowed me to exactly match the curves of the frame rail and gently form the joints to ensure a perfect fit.  With all of the tacks in place, I stitched the panel in place by staggering small, half-inch long welds around the seam until the entire seam was welded solid.  I also filled in all of the plug welds I had made room for and ground everything smooth.

With all the welding and grinding done, I moved on to applying a small amount of All Metal filler to the surfaces to ensure I had everything smooth and to fill the slight remains of the "ding" left in the inner frame wall that I couldn't safely pull.  With everything skimmed lightly in filler, I had a bite to eat for dinner with the family and let the works dry.  About an hour later, the filler had set nicely and I sanded everything smooth.  The end result is something I am quite happy with.  Since this car will be converted to power rack & pinion steering, I have decided to fore go drilling the two lower bracket holes for the original P/S ram bracket in the lower frame to keep everything tidy and weather tight.

The next step is to order a new corner brace from CJ Pony Parts so I can complete the torque box to frame corner area and prime the works again for protection.  One more headache out of the way!

Frame lip was the first repair.  Here the patch has been trimmed and fit to the frame and is clamped into position with locking pliers.

Here is a look from the bottom (actually top) of the frame lip patch in place.

Frame lip patch tacked into place.  A little hammer and dolly work was required at this point to slightly tweak the curvature of the lip to match the frame rail.

Although you can't tell it in this picture, the lip patch was fully welded on both sides of the seam to ensure weld penetration and strength.

Finished lip patch from the bottom.

Finished lip patch from the top.

Here, the lower frame rail patch is clamped into place after the final tweaks were made to get it fitting just right.  Plug weld holes have been drilled along the lip flange as well.  Next, the patch was blasted clean in the blast cabinet and the inboard side was coated with 3M Weld-Thru primer before welding.

The patch is fully welded in by staggering small, half-inch long welds along the seam.  You can see the relatively small heat affected zone around each weld which keeps warpage to a minimum.

With the welds ground flush, the patch is virtually undetectable from the original frame sheet metal.

Another angle of the completed repair.

I added a thin skim of All Metal filler to make sure I ended up with a smooth repair and to fill the dimple that remained near the rear mounting hole.

Here is the completed repair ready for the installation of the corner brace and then primer.


  1. Terrific job on that patch good looking and (importantly) as strong as the originaly steel.

  2. Thanks for the kind words Mike! I have to admit I was really agonizing over this particular repair. Once thought everything through, I just stuck to the plan and it turned out remarkably well. Whew!

  3. Nice work there Sven. The All Metal is a nice touch to keep it looking original. I should have used it for my various patches.

  4. Thanks Alex! All Metal really is one of my favorites, particularly where metal finishing won't take care of all the little imperfections. The high metal content does make it a bit tough to sand, but it is very durable and finishes as close to true metal than any filler I have ever used.