Braze quarter panel replacement?

[OrangeTwister]

My Duster needs a new quarter skin and there is a small one man show Garage in the town where I grew up. Last weekend when I headed up to visit my sister I saw the bay door open so I stopped in. The place still looks the same as it did when I had my 69 Barracuda there when I was in high school.

Back in the day this guy painted many a hot rod and he painted the up and over stripe on my 69 back in 1977.

So we start shooting the breeze about the old days and I tell him about my Duster and I ask if he still takes on work like my quarter replacement. He looks at me like I'm insane and says "why do you think I'm still here."

There is a 78 short bed power wagon on jackstands and the restoration work looks really nice.

He tells me if I can leave the car from a Friday morning to the next Monday he can replace the skin for $550 labor plus the cost of the material.

I like the price and there is something about getting it done by the old timer that makes it all seam perfect.

Except, he still brazes panel repairs. I read somewhere in a thread on this forum that if you have a brazed repair you should grind it out and mig weld it?

I need some feedback on this from you all.

 

[67Dart273]

HEH. I would bet you that in the years I was "mostly young" that the vast vast majority of panels was brazed. I recently saw a program on PBS on how they put Rolls together. They have wirefeed brazing guns that welds the top corners to the rest of the car

 

[68gtxman]

HEH. I would bet you that in the years I was "mostly young" that the vast vast majority of panels was brazed. I recently saw a program on PBS on how they put Rolls together. They have wirefeed brazing guns that welds the top corners to the rest of the car

Are you saying that there should be no problem with brazing? I've often wondered this myself, but I've never done any research on the topic.

 

[67Dart273]

I think it's all in "who's doing it." If this old guy is GOOD and comfortable with "his ways," then fine. "Modern guys" would mig the thing.

You get a hack that can't do either, and a "hack job" is what you'll have

 

[OrangeTwister]

I saw a post in the bodywork thread that you cant use most body fillers over the brazed seam.
I like the guy and I trust him, but Id like to know what you can put over that weld.

 

[GaryS]

I stripped and am in the process of restoring a '56 Plymouth. Except for spot welds, all other factory panel joining was brazed and it still looks good.

 

[Dartnut]

Being a welder, i know the brazing process well.
Brazing is actually oxy/acetylene gas welding not only using a brass rod for filler, but can be, which is a modern misconception.
Leading or soldering a seam is a brazing process for example.
The key is heat control and cleanlieness as well as fitment of the panel.
A lot of old school bodymen are experts at this, and use a process called ''hammer welding'', where they weld for a few inches and hammer and dolly the panel straight while it's still hot, an adaptation of ''forging''.
That being said, the steel on the older cars (50s and older) was much thicker and heat control was much easier.
The steel on your a-body is a lot thinner, and a lot trickier to work with, but is do-able if you really know what your doing.
My real problem with it is the strength of the ''weld'' if he is using brass as a filler/joining rod.
When using brass, solder, or lead over a seam over a long distance panel, it is inherently weaker than say a mig weld.
How brass rod brazing actually works is that the steel pores swell when heated and the brass flows into them, and when cooled, the pores close in on the brass causing the bond.
Think of it like velcro, but with a much tighter bond. It's almost like glueing the panels together, so to speak.
That being said, the expansion/contraction rates of steel and brass are considerably different, so if left in the heat and let cool especially rapidly, the panel will expand differently at the seams causing a lot of movement. Think of the scenario that the car is in the hot sun and a rain storm comes up suddenly and pours rain on your car, cooling it off quickly.
If you have a realitively thick layer of bondo on the repair, it will crack out fairly quickly. That's if the panel isn't fit and finished very well and there is a lot of warping that wasn't taken care of in the hammer welding process.
That's why mig welding is superior to brass rod brazing in panel replacement. The expansion/contraction rates are the same because you are using a similar metal to join the two, you are actually melting the two pieces together for a stronger bond, and the risk of warping the panel are diminished by a lot.
This is why bondo cracks out over time usually on any body panel where it's laid down too thickly, it's the expansion/contraction rate of it versus the steel that's under it, and bad prep of the panel before slathering it on.....
That's given a best case scenario versus a worst case scenario.
I hope this helps,
Tom.

 

[BillGrissom]

Sounds like a great price. I paid $1200 20 yrs ago to replace the qtr panel & rear valance in my C-body, with me providing the panel.

I have read that a braze can be as strong as a weld. You can find photos of test specimens where the base steel broke before the braze joint. I sure wouldn't worry about strength in body panel joint. Traditional filler material is lead, which is still de rigor on high-end classics, so if he uses that be real happy.

Probably the only concern with braze is if the seam will show temporary distortion as ambient temperature changes. I have heard that TIG is not good for that reason. Being a softer material, or such, you can get differential thermal expansion, so a straight panel at 70 F might look slightly wavy at 30 F or 120 F. Probably not noticeable unless the seam is in the middle of a flat surface, like many partial qtr panel repairs, and more for concours judgement of a shiny trailer queen.