I wrote previously about "repairing imperfections, old and new", where I discussed fixing different problems on a 1940 Schwinn New World bike, some of which were always there and some that resulted from years of hard use.
A recurring problem on pre-World War 2 Schwinn New World bikes is the breakage of the fragile wire fender braces they used. The braces tend to crack around the rivet hole because not enough material is present there.
Fixing old parts like this is a challenge. There are no direct replacement parts made today, so you have to get creative.
Let's use the fragile Schwinn wire braces as an example. There is no "kit" to repair these kinds of very old parts. I had a handful of them to repair. Some were cracked, and some were totally broken. In my book, a viable solution should fix both a broke and a cracked brace. Be creative and consider your options. I got some help from a couple of family members who know how to weld. I also did some soldering and brazing.
Arc/Stick Welding: an old school method, but not delicate enough for this job.
Flux core: Small flux core welding machines are popular do-it-yourself options today. Initially the flux core machine burned through the spine of the brace. After adding donor material from the head of a nail and turning the machine way down, a successful weld was made. The weld then had to be bored out for a new screw/rivet hole. The boring out process is a challenge because the welded area is kind of hard. A carbine Dremel head worked best to bore a new hole.
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| Flux core with donor material - notice the wider center. |
Brazing: A traditional solution. Works adequately on the braces, though does not add as much strength as welding with donor material. But if you have a decent propane or Mapp torch, brazing is an option to fix a broken wire brace. Boring out the hole is easier because brazing is softer than weld material. This will fix the braces adequately for their purpose. It's very much possible to re-break them if you're rough. The brazing rod material flows and sticks nicely on the steel (make sure the material is clean and you use flux).
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| A broken brace, brazed back together |
Oxy/Acetylene Welding: An old school form of welding. Similar to the brazing process but harder material and higher temperatures. Doable. My understanding is that this is kind of a by-gone process and most people who weld opt for MIG, TIG, or one of the portable flux core machines. (But gas welding is by no means obsolete - it was a go-to method for much of the 20th century).
TIG Welding: A modern form of welding preferred for delicate repairs. This would be a good solution as well. The material needs to be clean. I have a lot of respect for people who can TIG weld and get the "stack of dimes" look. If you know how to TIG weld, you probably don't need my advice.
Silver Soldering: Too weak to be effective, even when washers were used to help provide rigidity. I tried this three times: once with just solder (don't bother), once with a single washer as a backer (weak), once with two washers as backers (a bit better but still too weak). Even basic testing allowed me to pull apart the repair. Avoid this for these kinds of braces.
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| Silver solder with backers - an interesting idea that didn't work |
Suggestions: TIG Welding, brazing, or gas welding all would be options. Flux core is an option if you are careful and have donor material (and you don't mind working to bore out a new hole). Don't bother trying to use an arc/stick or silver solder.
What about that cracked front fender? I previously wrote about how the bike was delivered upside down, with the bottom (now the top) opened. The front fender was cracked in the process of being slammed around in shipping.
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| When the arrow on the box is merely a suggestion... |
The fender sheet metal is very thin, even by today's standards. So as with the limited material on the braces, processes like arc/stick are probably a no-go. It probably would just burn through the material. The flux core welder also was at the edge of its abilities with the braces. Here the metal is even thinner. I suppose with donor material it could be fixed, but I think that metal is too thin for the flux core.
After some thought, and the experience with the braces, I decided to braze the cracks. The fender doesn't carry much weight, though something more than silver solder or epoxy is needed here. So out came the torch and I brazed a couple of lines along the cracks. One side got a little more braze than was strictly needed, but with smoothing it will look fine and stop any more cracking.
The next jobs are to patch up the paint in the repair area and get things re-assembled.
