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Quarter Panel Patching Questions

8K views 12 replies 4 participants last post by  diety motorsports 
#1 ·

Excuse the gold, it's only there because my friends and I found it hilarious combined with the primer.

Right rear:


Right front behind door:


RR patch:



All 4 patches:


So basically, I have rot in front and behind both of my rear wheels. This is the only real rust on the car, aside from the passenger door which I already have a replacement for. I have these practically rust free cutoffs from Arizona, which are going to get media blasted before going on. I also won't be using the entire panels, just enough to cut past the rust a good couple inches.

Behind the rear wheel, it rotted enough for a rat to climb in and stuff almost all of the headliner padding into the quarter panel. That was fun to remove...


I'm planning to butt weld them. I have access to a Lincoln MIG setup with argon, although I'm not a terribly great welder yet. I haven't done much with sheetmetal. Also, the way I was planning to weld it on, I won't have enough access from inside/behind to tap it out with a hammer and dolly.

Questions:
1. Any tips/things to watch out for there? I'm under the assumption that I'm going to have to alternate and tack it, not running a bead anywhere.
2. Can I flare the edge outwards a hair, then weld and have it end up mostly flat after I grind down the welds? From what I've heard seams like this tend to sink a little from being welded.
3. What can I do to get it as smooth as possible without using filler? I'm planning to use a skim coat of fiberglass over top to finish it up but I'd like to keep it to a minimum.
4. Any tips on lining it up and cutting it to fit properly? I was planning to cut out a template, and trim the panel and car to match so it sits pretty close - leaving a little extra so I can slowly trim it until everything fits closely.
 
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#2 ·
John68040 said:
Questions:
1. Any tips/things to watch out for there? I'm under the assumption that I'm going to have to alternate and tack it, not running a bead anywhere.
2. Can I flare the edge outwards a hair, then weld and have it end up mostly flat after I grind down the welds? From what I've heard seams like this tend to sink a little from being welded.
3. What can I do to get it as smooth as possible without using filler? I'm planning to use a skim coat of fiberglass over top to finish it up but I'd like to keep it to a minimum.
4. Any tips on lining it up and cutting it to fit properly? I was planning to cut out a template, and trim the panel and car to match so it sits pretty close - leaving a little extra so I can slowly trim it until everything fits closely.
1. Make small tack welds and let them cool naturally. Do not cool them with air or a wet rag. You'll shrink the metal this way. Make your tacks every six inches or so, let cool, then go back and push a tack bead onto your cooled, previous tack bead. I feel the weld with my hand to make sure it's not warm to the touch before making another weld.

2. The seams sink because the metal shrinks. Even if you flare it, you will still get shrinkage. Those aren't big replacement panels with wide open weld runs at the seams, but since you haven't mastered the welder you should plan on some pretty ugly welds that you'll probably have burned in there pretty good. Welding is very difficult to do well initially, and it takes a lot of time and practice to get good at it. I actually find butt welding to be easier than lap welding.

3. Since you've never welded before, you should just plan on having to use filler rather than trying to get a weld so perfect it will require hardly any filler. And I say that because you're just going to have a difficult time getting it to that point, being a novice and all. Keep in mind when you're grinding down your welds, the grinder generates immense heat as well and can further distort the metal if you keep it on one area too long. Don't dwell on any one spot, and jump around alot, letting your welds cool before going back to hit them more. If you can fit a dolly in from the back of the panel, hold it up tight against the back of the weld, then do on-dolly hammer on the weld from the front, this will stretch the metal and you'll actually see the metal start to flex back out. It's exhausting work though.

4. What I've found works really well (and accurately) for me is--if the replacement panel can fit directly on top of/over the old panel--use metal screws and screw it down to the old panel nice and tight so everything lines up well. Then take your cut off wheel and cut right along the edge of the new panel. Unscrew the new panel, continue to remove the old panel if needed, and the new panel will fit right into place and your cut will line up perfectly since the edge of the new panel actually guided the blade. It automatically leaves for a bit of space between the edges of the panels because you don't want your new panel actually touching the original panel if you're doing a butt weld; there needs to be a tiny bit of space between them.
 
#3 · (Edited)
Lizer said:
3. Since you've never welded before, you should just plan on having to use filler rather than trying to get a weld so perfect it will require hardly any filler. And I say that because you're just going to have a difficult time getting it to that point, being a novice and all. Keep in mind when you're grinding down your welds, the grinder generates immense heat as well and can further distort the metal if you keep it on one area too long. Don't dwell on any one spot, and jump around alot, letting your welds cool before going back to hit them more. If you can fit a dolly in from the back of the panel, hold it up tight against the back of the weld, then do on-dolly hammer on the weld from the front, this will stretch the metal and you'll actually see the metal start to flex back out. It's exhausting work though.
I have some experience, but it's mostly with thicker metal. I'd like to at least try to get it as smooth as possible and see how it turns out, I know I'm going to have to use filler but I feel it's worth the effort to try to minimize it. I was definitely planning to take my time with the grinder to avoid warping.

Lizer said:
4. What I've found works really well (and accurately) for me is--if the replacement panel can fit directly on top of/over the old panel--use metal screws and screw it down to the old panel nice and tight so everything lines up well. Then take your cut off wheel and cut right along the edge of the new panel. Unscrew the new panel, continue to remove the old panel if needed, and the new panel will fit right into place and your cut will line up perfectly since the edge of the new panel actually guided the blade. It automatically leaves for a bit of space between the edges of the panels because you don't want your new panel actually touching the original panel if you're doing a butt weld; there needs to be a tiny bit of space between them.
This won't work with the shape of the patches unless I cut them up. All of the patches are inner and outer together. I am aware that I need to keep a slight gap. I figure if I make a template of some sort and cut the patch piece to the exact size of the part I cut off, I should be good, right?

Thanks.
 
#5 ·
deadbodyman said:
ON A 77 PINTO ?????
seriously ,if it were me I'd separate the inner and outer skin put them in the cabinet blaster then epoxy them, screw the outer piece on where its supposed to be then the inner,take the outer skin back off and weld the inner then weld the outer
Nope, on an '80. Daily driver when there's no salt on the roads. 76 motor though I found out, haha.

Separating the skins isn't a bad idea. I could weld the outer and have access to it from the back to get it nice and smooth. I'll have to take a close look and see if I can separate them on the seam easily enough. I'd like to avoid screws because that's more welding later on to fill the holes.

I was thinking about making a simple magnetic stand like one of those scissor-type lamps to hold it in place, or just have someone hold it while I do a few quick tacks.
 
#6 ·
The nice thing about using drill screws is once you put it all together and everything fits just right you can unscrew the outer skin and have ez access to the inner for welding then just screw the outer back on exactly where it was using the same holes and weld that,,, you'll have to drill the spot welds to get it apart ...
 
#7 ·
deadbodyman said:
The nice thing about using drill screws is once you put it all together and everything fits just right you can unscrew the outer skin and have ez access to the inner for welding then just screw the outer back on exactly where it was using the same holes and weld that,,, you'll have to drill the spot welds to get it apart ...
You're talking about doing an overlap though, right? I wanted to butt weld it, so there'd be nothing to screw to unless I added a piece to hold it together temporarily.
 
#8 ·
Once its screwed together and everything is in place both pieces will be overlaped but you take the outer piece off and mark exactly where you want to cut the inner piece then you take the inner off and screw the outer back on and mark that from the backside ...after you make the cuts you use the butt weld clamps to hold it together while you do the butt weld.
 
#9 ·
deadbodyman said:
Once its screwed together and everything is in place both pieces will be overlaped but you take the outer piece off and mark exactly where you want to cut the inner piece then you take the inner off and screw the outer back on and mark that from the backside ...after you make the cuts you use the butt weld clamps to hold it together while you do the butt weld.
Sounds like a good idea. I'll keep it in mind when I decide how I'm going to do it. It really depends on how easily I can separate the panels along the seam.
 
#10 ·
You'll have to drill out the spot welds along the wheel well and door jamb...you can use a spotweld bit or even a low angle drill bit (I like drill bits) what you do is drill a hole through one piece but not all the way through ,if you have the right size drill and its centerd they should pop apart fairly ez .Back in 1980 I owned two Pintos a 72 and a 76 I loved them ,you couldnt kill em
 
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