I recently purchased a very rusty 1962 Cadillac convertible. I'm in the process of cutting out the rot (alot) and need to replace the bottom of each of the rear quarter panels. I have a donor car which I will also cut up to save the 'vert. My question is what is the best way to cut a nice straight line so I can match up the panels. These cars have alot of body lines and was going to cut about 1" below the center line. I have air shears, 3" and 4-1/2" cut off tools/grinders, sawzall, etc. Also I'm assuming I should take the area down to bare metal first to make sure what I'm dealing with right? Thanks, this is my first real foray into metal replacement other than small patch panels. This needs floors, rockers, quarters, etc...
cut the donor car's panels "big" with whatever, then trim with tin snips. cut the car "small" and lay the repair panel over, mark, and trim with tin snips.
Cut off wheel is what a lot of the fella use, some of the fellas use a saw zall. But I think that a cut off wheel is probably easier to handle for a long straight cut.
definately take it to bare metal to see what you have. i draw a straight line across panel where i'm going to cut it then rough cut it 1/2-3/4 inch on the junk side of line. then i clamp straight edge on line and use my 3 inch air wizz wheel as it doesn't distort the metal like my air shears do. sawz-all and skill saw with metal blade are to rough and hard to keep straight. mho.
A 1mm cutting disc,the type used for stainless steel,in a 4 1/2 inch angle grinder works for me.Gives a clean,straight cut and easy to control.
I've done the same as post #2, but with a cutoff wheel. However, if you're working on a straight long unsupported run on a quarter, you might want to keep an extra 1/2" of material on the car after you trace the replacement panel onto it. Go buy an air flange tool, and flange the panel on the car. If done right, you will have a depressed lip to weld the patch onto. It will be a much stronger repair and more forgiving, especially for an amature. Just make sure you seal the backside of the repair VERY WELL, or rust can set in between the panels you just installed. Don't cut any more than you have to from the car until you have the patch marked. You will need as many reference points as you can save to locate the new panel properly.
like other guys, air cut off wheel with a small disc.... It might be just me but I think the control with an air cutter is a lot better than an electric one.. and like mentioned, cut the doner big, and the panel on the car small..
Thanks for the tips everyone. I'm a little ways off on diggin in that deep but wanted to ask now so I can prep for the hard work I have coming up.
If he's asking how to cut a straight line, I'd hate to get into panel warp, tacking, and losing a gap with swelling while trying to butt weld the whole thing. He could end up with a buckled mess.
Cut the donor big and the car small. Set the repair panel over the car, put a couple tacks to hold it, draw a marking line, cut thru both panels with a cutting wheel or plasma cutter. grind the edges as necessary.....
sorry, your right. i step and overlap very little, but i've been doing it for 20 + years. small welds then blow with an air gun move the distant of you hand, placing you hand on the last weld made and cooled with air. if it's too hot keep blowing.
MJ, Mark, and I all use the Air angle Die grinder with a 3" cutoff wheel. Real easy to control and stay to your line.
Now that you say that, it would be a good idea (for my own info) to flange, then cut back to within 1/8" so there's a little meat to overlap instead of butting a gap in some cases.
So you are basically wanting to put a recessed lip on the car to receive the donor panel? So you have a small lap and more material to weld to? sounds like a good idea to me, plus it seems it would make the connection a tad more rigid.
4" electric grinder with a 4" narrow cut off wheel will get you a straight cut better than anything else. cut the quarter small, and the patch big. get the patch exactly where you need it, then cut through both at the same time if you are going to butt weld. a long butt weld is a pain to do compared to the overlap/flanged panel method. if you go the flanged panel way, flange the body, since any water that may get to the backside of your work will run down hill, if you flange the patch there will be a nice long trough for the water to run in and destroy the whole repair over time. be sure to get some seam sealer on the backside if you flange it. I got a pnumatic flanger at harbor freight (or was it eastwood?) not too expensive and easy to use. before that I had a customized set of vice grips for flanging. too much work. as for how big a chunk to cut out, I like to cut a bit above the obvious rust, then look at the backside of what you just cut out. if the back side is all rusted and pitted, cut some more until youhave good metal on the outside as well as inside.
yes and your panel doesn't have to be real "straight" as long as you follow the repair panel. if i can get to the back of the panel i'll sometimes "step" it after ward with a dolly that has a groove cut in it [basically beating the weld in] seams to pull the metal in.
Seconded. I have a pneumatic flanger for this purpose. It makes lining up everything nice and easy, even if I end up with a bit more to fill in. My welds suck, so I need all the give/take I can get. Having said that. the passenger side rear heatwarped on me when I put it in, I'm going to have some cutting and fitting to do in the spring...
I grind both panels and cleco the replacement on top of the original. Then take a 1/16" cutoff wheel and cut through both panels for about a foot and remove the pieces so that I can butt weld them together. Start with small spot welds to avoid warpage, continue until it's welded solid and then remove the next foot and re pete.
Whizzer or a air saw make the best cuts. Take your time and go slow. Go big to start then widdle it down for fit.
Lap welds on body panels are bad mojo. It creates a void for rust to start and an area that cannot easily be primed or painted to help prevent that. It also makes a seam that doesn't expand and contract at the same rate as the rest of the panel, which can lead to wavy panels when the panel heats up in the sun. On the flip side it is a whole lot easier than a but weld. Its your car pick your poison. Good Luck, Kris
Guaranteed way to get a perfectly matched joint, fast and easy. Works for linoleum wallpaper Wood anything else you need to match. You wanna really straight line , cleco a small leg light gauge angle iron, to the pc you wanna keep. Run you're cut off wheel on top of a angle.
Duuude...... Put the whole quarter(skin) on it Pull the belt stainless and drill out the spot welds. The only weld bead you'll have exposed that you'll have to work is above the deck lid, ala package tray.....or taint (t'ain't the package tray but t'ain't the trunk...in between the two) and at the rear body panel across the trunk gutter(and the bumper hides most of that!) Plug weld the bottom to the trunk drop-offs, and around the wheel opening, and you're done till you hang the rocker. PLUS......you can clean and POR the inner structure You will have a little more time harvesting the whole donor quarter skin, but save tenfold in grinding, warp abatement and bodywork ! (pssst....I've got one of those rusty 62 converts too)
Hey, I'd be a cold day in hell before I'd be a player for a step flange on the quarter of a drop top! Even with a convertibles' beefy frame, these still have quite a bit of flex to them when on the road. That and given the length of a Caddie's quarter, and the amount of filler you'll probably need to cover that step flange & weld I say no way, not on my watch! Too, step flanges have been known to trap water, and ''whitness or ghost'' in the hot sun, after paint. A "wizzer wheel, air saw or even a good jig saw with metal cutting blades all will offer a good, straight, clean cut. Measure, measure & measure again, and leave plenty of meat on the replacement panel for the ''oh,shit'' factor. I'd remove all of the paint, well above the seam you'll weld to, and up to the body line above, infact, I'd strip the vehicle to bare metal. If you've rust in the lower areas of the vehicle it's probably above the skirt areas, as well. A picture would be a great help- " Do not be to quick to drink the Kool-Aid "
I agree with everyone about cutoff wheels, and cutting the patch panels big so you can inch up on the final cut. One more tip is to use flexible metal rulers to get the scribe lines as straight as possible. It seems to make my welding easier when I have a nice tight panel gap that is straight and true.
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