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Weld Mold 26-C 'How-to' Oxy-Acetylene Repair: Restoring a Stretched Bore in Stamped Steel

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I just completed a shop project worth sharing.  An older suspension arm made of stamped steel (mid-'50s vintage) had a ball-joint bore issue. The lower ball-joint was originally a thread-in style—classic Mopar with torsion bar suspension, and the replacement ball-joint is a press-in type. These ball-joints are at the loaded arm, so press-in can work well if the fit is correct.  The upper arm uses a threaded, OEM style replacement joint.


The lower arms had the ball-joints replaced years ago, and the method called for pressing new, unthreaded ball-joints into the original control arm threads.  This being the second time around for press-in joints, the new ball-joints would not fit as tightly as desirable. These control arms are essentially obsolete parts.  Otherwise, a new arm would be an option. 


As a hard rule, we never apply heat to automotive parts or steering linkage, especially parts that have been heat treated—like steering linkage, axle shafts, splines, shafts or gears. In this case, however, the control arm is simply stamped from a heavy sheet of "mild" or cold rolled steel, and the OEM/factory commonly welds attachments to these kinds of parts.  (See the rather crude welds at the last photo, these are original, 1950s era welds, a plate welded to the control arm—at the factory!) 


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There were several options, including TIG weld "facing" or build-up and other welding processes.  The approach that made the best sense for restoring the bore size at the flattened "threads" was the use of oxygen-acetylene process (a torch and correct tip) to flow a thin, even layer of Weld Mold Company's 26-C alloy flux-coat rod atop the remnant threads. (Click on each photo to enlarge for viewing.)—Moses


This alloy rod has exceptional properties, as noted in the Weld Mold Company's description:


Weld Mold® 26-C


"A flux-coated alloy with super capillary action and thin flowing characteristics. Produces extraordinary tensile and shear strength. Deep penetration of the grain boundaries on the surface of the base metal without fusion permits application with a minimum of heat and distortion."


Specification: AWS-BCuZn-A [Properties]

Available forms: Oxy-Acetylene


The oxy-acetylene process for 26-C, essentially like "brazing", applies much less heat than fusion welding; this is desirable for minimizing risk of distortion and heat affect.  Reduced heat and allowing a still air cool down (at 80-degree F ambient temperature) helped protect the base metal.


Application was simple.  Prep work included glass beading and thorough cleaning.  I then heated the thread area, much like brazing, and worked the oxygen-acetylene torch and flux to produce a smooth, strong alloy layer with exceptional penetration of grain boundaries.  I kept the flow to a thin, uniform layer...Note that 26-C is high tensile stuff and requires burr grinding to reduce high spots, so keep the layer uniform and at the desired thickness!


The result is a strong layer that will behave like higher tensile metal, much stronger than the original stamped steel!  Very strong in place plus shear resistant, Weld Mold 26-C flux coat rod requires only normal oxygen-acetylene, brazing-type application process:


26-C Technical Data from Weld Mold Company:

  • Available Processes: Coated Oxyacetylene rod
  • Hardness: 120-160 BHN
  • Tensile Strength: Up to 100,000 psi
  • Bonding Temperature: 1600° F
  • Class: RBCuZn-D

Weld Mold Company serves industry and the tool and die shops, types of welding and brazing that require precise, predictable outcomes. Niche products like 26-C target specific tensile strength, shear resistance and chemical properties found in expensive tooling repairs. 


For alloyed steel and metals, the Weld Mold Company specialty, selective niche filler materials are available to match base metals precisely—even allowing for the re-heat treatment of the piece where necessary—using the exact method of the base metal!  (See my comments in the metallurgy post on annealing and "normalizing" metals before making repairs or fabricating components.)


I have relied upon Weld Mold Company products for years, and we are proud to have Weld Mold Company as a sponsor at the magazine!  The precise metallurgy in Weld Mold Company products, for both welding processes and brazing, has made many of us more aware weldors and raised our interest in chemistry and metallurgy, the science of metals.  Better yet, Weld Mold Company takes the guesswork out of selecting the right filler materials for a given job—see the Weld Mold catalog!


Note: At the magazine site, there are a variety of projects that illustrate my use of Weld Mold Company fillers. See the Adobe Flash Player video slideshow about gear tooth restoration from my presentation on repairing an obsolete T85N transmission cluster gear.  The gear was originally cast from 8620-type alloy metal, machined and then case hardened.  (I discuss metallurgy and heat treating needs here, too.)  The narrated slideshow presentation includes a transmission iron casting repair as well.  This presentation is one segment from my guest speaker role at the 2011 Midwest Willys Reunion.  I also discussed a large cast iron axle housing repair done with TIG process.  That video slideshow is available at the magazine, too.  Click here to access the iron tractor axle repair slideshow in Flash video, which you can view using free Adobe Flash Player...


These kinds of restorative repairs begin with choosing precise, niche Weld Mold Company filler metal products!  Coupling Weld Mold Company welding filler materials with the stability and performance of a machine like the HTP America Invertig 221 TIG and arc welder produces phenomenal results...


Whether you're a 4x4 shop owner, a machine or tool-and-die shop, or a serious metal fabricator of off-road vehicles, Ultra4s, dirt motorcycles or OHVs, get to know the folks at Weld Mold Company—learn about metallurgy and go up the metal fusion and brazing learning curve!



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