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Posted by David Sherman [24.32.202.83] on Thursday, February 25, 2010 at 18:15:10 :
In Reply to: windshield frame repair posted by Paul D Hoffmeyer [75.17.220.155] on Thursday, February 25, 2010 at 16:57:52 :
I used Titan Super-Weld metal-filled epoxy on my rusted out M37 frames almost 15 years ago and they're holding up okay, as is the polyurethane sealer I used in lieu of the proper weatherstripping to glue the glass in. I definitely recommend the Titan (now bought out by some other company) over "J B Weld, which has never worked well for me. The main thing is to get the metal-filled stuff. Titan "Super Mend" is not metal-filled, so don't use that.
If it was a vehicle I really cared about, I would try the solder. The "lead" used for old-time body repairs is basically a tin-lead solder that's designed to be mushy over a wide temperature range, rather than to melt completely at one particular temperature. You might consider using that, so you can sculpt it a bit. The modern unleaded plumbing solder (95% tin 5% antimony, I believe) is too runny for this, as is 37/63 tin/lead electronic solder. 50/50 tin/lead solder is better, if you can still find it. I'm not sure what the composition of the body lead is.
The electrolytic cleaning process leaves a bit of a black oxide coating, almost like bluing, that you'd need to get through for the solder to stick. There's nothing like acid to do that job, and a strong acid (zinc chloride) flux is what's needed for soldering bare steel. In my experience, ordinary copper plumbing flux is not really strong enough for steel. I have made my own by dissolving scrap zinc (save those zinc boogers that you sometimes find in with galvanized nails) in muriatic acid until it won't dissolve any more. A paste of ammonium chloride (sal ammonia) in a little water is milder but will sometimes work. Probably the people who sell the lead for body work sell a suitable pre-made flux.
The heat of soldering will not warp the frame, and if you can get it to stick, I think you'll have a repair that will last forever, unlike epoxy which will eventually deteriorate. I would also not be afraid of brazing, especially if some strength is needed, as in corners. For situations where I need to build up some metal, I have some cadmium silver brazing rod that is mushy over a wide temperature range and allows you to build it up in whatever shape you need. It's good stuff for filling gaps (not so good for flowing down into cracks), and ordinary borax brazing flux works fine with it, but it's not much used these days due to the cost of the silver and the toxicity of the cadmium. I happened to find it in a military surplus lot.
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