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Discussion Starter · #1 ·
I am ready to do the rear quarter panels on my 70 Roadrunner. The question is do I lap weld them or butt weld? Is there an advantage to one type or the other? Also are there any things I should be aware of before I cut into my baby. I am aware of the warpage issue and using the stitch method. I read a post a while back where someone mentioned the use of some kind of primer that resist rust in places where you do not have access to after welding. Can you tell me the name of that paint and if there are any special considerations in using it? Do I grind down the welds as i go along, or wait until the whole panel is done? If anyone has pics of a panel they have done in stages or just before grinding I would like to see them if that is possible. The last question is what should I use over the welded area after grinding? (fiber glass, bondo or do you have something that is better than those items)? Thanks for your suggestions!!!
 

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Well,i like to crimp a flange with a flange tool so when you set your panel it lays right in there and it actually gives you some support behind the panel edge also.Just remember "measure twice ,cut once".If you have to, trim a little at a time until you get desired fit.Pain in the rear but well worth it.Also with a flange,when you get done welding and grinding it will be very close to level and you won't have to use alot of filler.I weld everything up, get the welder out of your way and then start grinding.I know alot of the guys use POR15(i'm pretty sure that's what your refering to).I like DP40(PPG product)It's all good.The best thing to resist rust(just as long rust has not already started) is Primer(DP40 etc. etc.) then paint (just like the rest of the car.(if that's feasible)I mean think about it,how many cars actually rust from the outside.Usually none unless the paint is missing.Cured paint is a pretty solid water barrier)I've always just used body filler over the panel when done grinding.Although it does seem like the methods change as much as my underwear.About once a year lol .Some people will also tell you primer the panel before you start your bodywork.I've done it both ways and have had good results with both.I've been out of the trade a couple years so maybe some other bodymen "still in the trade"will chime in.Some guys also like to use a reinforced filler for the first initial coat(gorilla hair tiger hair etc etc).Sorry i don't have any pics.Good luck.

Carl
 

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[]{} except for the underwaer thing puke; also, the step created by the flanging tool will also give the edge some rigidity, as does working close to a body line. hey Carl, i could use a hand 8)
 

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Hey Dubb,I don't think i'm really that far from you.If your in southern NJ;i'm in northeast MD.Were probably only about an hour from each other.What city are you in?I'd be more than glad to help :).God knows my project is on halt for 2 reasons,lack of funds and i can't fit my car in the damn garage! :'( I'm gonna have to slide up to Jersey and check e'm out.I'll be sure to change my underwear before i come up. )(/*
Looks like you got everything ya need but if you ever need anything drop me a line, if i have it, i'll get it to you.Keeps us from having to buy tools for a job you might only use once or twice.We need that money for are projects 8). See ya Dubb.

carl
 

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I cut the old panel out but leave some extra. Put the new quarter over it and attach it with sheet metal screws then start cutting along the panel as close to the top as possible and place welds as you go. You can use a cut-off wheel or a body saw - the body saw with one of those thin blades works best. As you cut you can peel away the waste on the new panel and what's left of the old quarter will fall away inside the car and you'll have a perfectly butt welded panel. When you use the flange method it gives the panel a chance to rust as the flange can hold moisture. It works, but it's not the best way to do it IMO. Also, if you have your welder set right the butt welded panle will be just as strong as the flanged panel. I have a '70 Mustang in my shop right now where they used that method and there is a ton of rust between the old and new panel and now the only way to fix the car is to use a full quarter (not a big problem if they didn't cost $400!).

After you finish the weld always put Duraglass over the weld. It's like bondo but is waterproof and is impregnated with short, chopped up fiberglass strands so it won't crack. Duraglass is actually better than lead for making a permanent fill. The stuff's like a rock once it dries. Spread the duraglass on like bondo and cut it down with some 36-grit just before it sets because if you wait for it to eet it will be a bitch to sand. Then use "bondo" to finish the panel. I use Z Grip. I usually do all the mud work before I seal/prime but you can do it either way.

If you're afraid some guy might stick his melon in side the trunk looking for the seam, once your panel is butt welded you can even put a skim coat on the inside over the seam and no one will be able to tell you replaced the panel. You could never do that with a flanged panel.

Hope this helps!
 

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Discussion Starter · #8 ·
I was sold on the idea that the seam weld was the way to go. Now I'm not sure again? I don't care who sees the seam or the weld in my trunk and this car is not going to see much if any rain. I am still leaning towards the seam. I should be ready to cut by Friday. I took off the bumper today and saw a lot of rust that I was not aware of. I think, no, I know I will be replacing the trunk floor soon as well. The left side patch I bought two years ago is not going to work, as the rust cancer is higher than I originally thought. I will head over to Auto Body Specialties tomorrow and get the left side rear quarter.
 

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Personally, I'd do the flanging method on a smaller panel such as the bottom of a fender, a dogleg or lower rear quarter but for a full quarter I'd go with a butt weld. Once you start bending flanges in the metal all sorts of weird things can happen with the curves and shapes of the quarter and you could end up with a roller coaster running down the side of your car.

That's just me though, some guys may know how to do it and get it right.
 

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[]{} the flanging tool on a somewhat curved panel can be a problem.....i like to butt weld all the small stuff, but i use small overlap(in general) close to a body line on the long runs. in reality, every job is different; and []{} if it can be butt welded with out warpage thats the way to go. priming the flanges and overlaps with weldable primer will help prevent corrosion.
 

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[]{} very true! It is also alot of work to flange the whole side of a 1/4 panel.I was thinking more of your typical modern day car and just chopping it midway up the sail(which is only a foot wide).I have a much better vision now.I wasn't thinking a lower cut like along that first body line.Gospel Runner i would definitely do the butt-weld method like these guys said.The results will be just as good and i think you'll probably get done a little quicker.I would definitely go that route.Sorry didn't mean to be too confusing.

carl
 

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Remember to line up the new quarter with your doors (hopefully your hinges aren't worn out). Make sure your door gap is even along the rocker before you start and you should be good to go. You might need two guys - get the new quarter lined up and drill a pilot hole for the sheet metal screw and once it's lined up right and that first screw is in you're golden. Make your cut/weld as high up as possible. Try to keep it within a half inch of the top of the quarter because that bend in the quarter is going to stay rigid and will be more forgiving as it will not want to warp as much when it gets heated from grinidng and welding.

Good luck! It's fun getting new metal on the car! Don't forget to post pics when you're done. 8)
 

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I am glad I read this thread, seems like a good method. I live in NE Ohio, and we get A LOT of humidity and extreme temps. Needless to say condensation occurs on a regular basis, and will create moisture anywhere. Autos that never see rain "mysteriously" rust and this is why. That is a pretty cool method, as I need to do quarters on the Dart. I have a pneumatic flange tool, but around bends and corners, it is a nightmare to get right. This seems like a better approach. Duraglass is tough stuff. I skimmed my rear wheel wells after I sliced and opened them up. I have used it a lot it the past too. One thing, it will shrink like anything else, so make sure you let it dry out good.
 

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i like this stuff, i use the grey.....an old guy showed me back in the eightys. it hardens like steel, sands like wood. we used to repair and attach corvettes with it. its waterproof. i seal all my welded areas with it, then i rough it up for bodyfiller. it has 1001 uses. i am addicted to marine-tex. i could almost build a BBD with it.....almost. http://www.marinetex.com/PRODUCT PAGE_files/All MarineTex Putty/marinetex prod info.htm
 
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