Who says so? Hell, if you cover it with enough bondo, it lasts for at least 4o years that I know of......
Every Lotus and Caterham 7 (up until about 5 years ago) had a chassis with every single joint brazed. A very strong and long lasting unit.
The key there was no movement in the part and no flexing. Put it on a panel that has a bit of flexing to it or vibration and the results may not be the same but I saw a lot of guys braze patches in in the 60's and early 70's.
the whole lower 5 inches of my car has brazed patches from about 59-60. grille, fenders, cowl, doors, quarter panel and taipan Northeast car with typical lower rot still holding up well...55 years
I brazed a bunch of pin holes in a floor pan about 20 years ago (had access to a torch but not a welder). While tearing the car down recently to fix the floors with new pans, the rest of the floor had rotted out and left a spiderweb of brazing in its place. Hmmm.
All the older bicycles were brazed together, and I never saw one fall apart. I have used brazing for repairs for many years, and sometimes that is all that is left of it!
Exactly. A good braze job is as strong as any other form of welding. As Blackjack noted all of the early Lotus race and street cars were brazed (along with most other small volume British "specials"). Back in the early days of Australian drag racing we did not have ready access to TIG welders or 4130 tubing so we nickel brazed our "muffler moly" (mild steel) frames. The weld was way more durable that the tube if done right. Roo
No, it's not as strong as welding, its a capillary bond. Nor is it a substitute for welding, but if the bond requirement is less than that of a solid piece of steel it will do that job until the cows come home.
When I went to work for the best old time bodyman/painter, to learn the trade, he did nothing but braze his metal. at one point I even bought a MIG, back in 83 or 4, before they were common in shops. He tried it a few times, and put it in a corner to collect dust! What I learned from him, and my experience with brass, and later MIG. (I dragged it out a year later and taught myself to use it): It used less heat, so in some spots it is lees destructive than welding (warpage). It works very well under lead work. Plastic work, you had to be very meticulous to clean off the flux, and rough up the surface for it to stick for a long time. John used a spot blaster he rented, with built in vacuum, a couple years after I started. He used an air grinder, then a wire brush before that. If you try to butt weld panels and grind off most of the brass, you have a weak joint. You cannot hammer and dolly brass for very long after brazing, it cracks. On overlaps, it is super strong. it works pretty well for filling trim holes on flat surfaces (less heat, less warpage) Just be careful with your grinding. It works well on exhaust pipes and such, if you cannot clean the surface as well as you like. I fixed up an old custom (my 61 Dodge) that John built back in the late 70's early 80's. To preserve as much work of his that I could, I "tinned" over some of his brass work to give it longer life under the plastic filler. Other brazings, I just put a coat of epoxy primer over it before filling. I think separating the brass form the plastic filler will make it last a VERY long time! My theory is that the hardener in the bondo, an oxidizer, oxidises the brass, making it slick, and like rust, pushes the plastic away from it, eventually. But with thorough cleaning, and working to finish quickly, as to minimize contact with air, and sealing the backside (air and moisture invasion), this will give you less problems. My 55 Olds, I built in 82, still looks pretty good, and is done 90% in brass, the only method I knew. Except for a crack at the bottom edge of where the roof meets the top of the quarter, an area of high stress normally, even more in chopped cars, the bodywork is holding up well. Driven 160K miles over 20 years, all over the country.
Interesting discussion, I am about to start on project that has a lot brazed body work. I think I will still cut most of it out.
I'll be 78 next month, and I've used a torch off and on since I was about 15. And I agree that the most critical part of using brass in a body repair is to meticulously clean away any flux remaining after brazing. Have used it many times for jobs where warpage would be a problem, or just not enough metal left after rust removal to apply a weld bead. And getting sloppy about flux clean up can cause a problem. Most of the brass rod sold these days is flux coated, and that may be part of the problem., When I was younger brass rod was bare, and the flux was in a can, powdered. You punched a hole in the top of the can so that you could heat the rod for and inch or so, stuck it into the hole in the flux can's lid, and the powder melted a bit and stuck to the rod. Then you preheated to a dull red on the spot mechanically cleaned on piece to braze up, app;lie4d the fluxed rod and heated, with a slightly rich flame, till the brass began to flow. If you had properly cleaned the piece and applied the heat form torch to the work piece and let the rod just be in the edge of the spot, you would see the brass "wet" to the workpiece, and you then built a bead. Nowadays most shops, when they buy brazing rods, get the flux coated ones. Using these, your rod is coated with a layer of flux which is applied when the rod melts onto the workpiece, and that may be more flux than needed. With the old bare rod and a properly cleaned joint, the flux you got on the rod, you could control the amount. If the joint had been well cleaned, you could often go much further down the crack or seam than what rod was under the melted on flux section. When you needed more flux you would see that the molten brass wasn''t "wetting" to the work as well, so you stuck the rod back in the flux for another dose. Perhaps the excess flux presence is part of the problem? Too much of it down in the little porosity spots, crevices, whatnot? Difficult to reach and more of it, so maybe it wasn't all cleaned off in the clean up before paint or plastic filler was applied. Just seems to me there's more flux residue to clean up now with the flux coated rods.
I brazed bodywork for years and can tell you, there is no problem if you follow a few simple rules. 1) Get all the flux off there. Wire brush in a drill, a grinder, sandblast, however you want to do it but it must be clean. Any spot of flux will expand like popcorn. I used to keep a rag and a bucket handy and rub the hot braze joint with a wet rag. This made the flux pop off and minimized heat warpage. 2) If you leave any pinholes moisture will get in from behind and lift the filler. Bondo will lift before lead, but lead will lift given enough time. What the OP shows is just plain cheap work. It would have been just as cheap if those spots of braze were spots of mig weld which is how cheap shops do today. It appears to be a roof insert which is why it lasted so long. No water or mud splashed up behind to cause rust or lifting. I don't know why he cut it out but if it was not cracking or bubbling it might have lasted another 40 years. Food for thought for the anti bondo, anti brazing crowd. This obviously cheap, inferior job lasted 40 years. How long do you plan to keep your car? How much are you willing to pay for a longer lasting job? If you want to pay double, triple or more the shop can do it in lead. How much do you want to spend? (my experience in the trade tells me the customers who want the cheapest price, outnumber the ones who want the best job, at least 1000 to 1)
You can get bronze wire for your MIG welder, no flux needed. It works really well for certain things. The problem with bronze is that you get galvanic corrosion, which I think is as much of a problem as the flux. The best way to reduce corrosion is to get the metal really clean, then use a good epoxy etch to seal it off, before any filler goes on. You can't beat a good O/A butt weld, IMHO. I avoid brazing as much as possible.
It indeed was a roof insert, probably put in when the car was channeled in the 70's, or earlier (so I was told) The biggest reason I pulled it out was that when I was welding in the corner by the deck lid hinge, some foam glued to the roof panel near the rear window caught fire, and with my helmet on I didn't see the flame until it blistered the outer paint. The panel weighs about 50lbs, and it was ugly flat. It will get a proper top insert.
Not mentioned in above posts, but major automobile manufacturers in the '40's, '50's, '60s routinely used brazed joint seams for some panels on the production line. Roof panel to quarter sail panel, quarter panels to the panel behind rear glass/ahead of deck lid, being some that come to mind. Those seams were leaded in those days. Most held up well for decades, though some eventually cracked or the lead lifted. Ray
We would take the roofs on stock cars off in order to have access to mount the roll cages. All of those roofs were brazed back on, A & C pillars. Some even looked pretty. I've had wheels and hubs from other cars bounce off the A pillar a couple of times, held up pretty well.
Does it work? Done right, yes. Is it good or preferred? No. I'll take a well done and controlled TIG over any thing, a MIG with soft wire next, O/A weld after that if I'm into the work. Brazing is one of those old "fix" repairs when it comes to cars that seems to hold up if you're willing to correct it. Bikes, light weight race cars, tubing, sure, a tried and true old process. Body work? Not in my shop any longer. To many easier (more profitable) alternatives. If I ran across a stellar braze on an existing car I'd clean, tin and solder it down rather than waste time tearing it out. The basic shit braze, bye-bye...
Brazing lasts real well. In about '83 I brazed patches into the rocker panels of an OT caddy for a fella down in the Ozarks while we were fixing it up for his missus. They live about 7 miles down a gravel road, it has been repainted since then but the brazed repairs are still holding and it is her only car. LOL Where I have found that brass doesn't hold well is in a high vibration situation like exhaust pipes. But on body panels it seems to hold up real well.
It would be nice to have Bill Hines or Geo Barris chime in on this thread. maybe some of you YOUNG guys would learn a thing or two about brszing.. Flux for uncoated rods was plain Borax.
I feel that it is still a good skill to learn. At age 19 I had learned (in a welding class) how to torch weld, brazing is way easier. The last brazing I did was with the flux-coated rods, IIRC, a brand name of Cold Braze with a pink flux.
I have actually used Boraxo straight out of the can. I don't think you can even buy it any more. There is a distinction that maybe we should make here, brazing with brass and gas welding with steel filler are both called brazing in some circles. I have actually gas welded chassis with steel filler or brazed them if you will, had had them hold up just fine. You don't have to use flux with steel. When I was in welding class in high school we had to learn to gas weld before we could stick weld. One of the things that they taught was that brass was for welding unlike metals, say cold rolled to galvanized. We also learned that if you needed to you could braze cast iron and have it hold up just fine. We all had to produce a broken piece of cast iron and braze it back together. For my unlike metals and for my broken cast I used exhaust manifolds. Unlike metal I brazed a piece of plumbing pipe into a rams horn so it would clear the steering in an AD truck and for broken cast I just made a split out of an inline 6 manifold.
I'm quite fond of silicone bronze and tig welder. Metls at 1800-1900 degrees with tensil strength 25,000 to 35,000 ( 1/2 that of steel)
I got some pieces here stuck together that way. Done correctly it makes for a very good looking weld almost like it had been furnace brazed. The doors on this heap were brazed shut in about '59 or '60. I was going to make them open again but have decided that when I get to it I will just leave them it won't be a streeter anyway. You really can't see it in this pic and I am not close enough to get a different one for ya.
The English brazed joints are not done with flux coated brazing rod. They use a spray fluxer and a special rod that looks like standard braze but is stronger.( Nickel bronze) The Brits built there racing motorcycle frames , race car frames and airplane motor mounts using this method for years.
ago is correct. The stuff to use for structural brazing is nickel bronze as I mentioned in my initial post. I have seen mild steel frames that have been in wrecks where the welds were undamaged but the tubing itself was torn apart in the impact. The nickel bronze is quite a bit lighter gold color than regular brass rod. I usually use silicon bronze (with my TIG) to flow a fillet around the outside of the tube to flange junction when building headers. I steel weld the pipes to the inside of the flange and then use the sil bronze to support the pipe on the outside. The fact that less heat is needed for the bronze weld and the radius on the filler seem to help keep the pipes from cracking at the flange. Roo
Roo I am sure that you are aware of this but maybe someone else isn't, with the silicon bronz and a tig welder you can actually make a weld that is much like a sweat joint on copper tubing. it is not superficial as it may look on the outside.
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