Q. I have a 1960 Chevy Stepside and I want to make the rear fenders wider. I presume the technique is to slice the fender from front to back, space the outer portion where I want it, and weld a filler piece into the gap. I don't know if it's better to cut the fender in the middle or closer to the mounting flange? Should I butt-weld the filler piece or use an overlapped joint? Thanks for your help and I hope to hear from you soon.
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A. I'd suggest making the cut about ¾ inch to 1 inch from the bed, as shown in the drawing. A lot of people use overlapped and stepped joints for this type of work, since the fit-up is easier, but I prefer to butt-weld everything. I believe butt-welded joints offer several advantages.
Since everything stays the same thickness, it's easier to work the joints smooth with a hammer and dolly. When some areas are double thickness, it's difficult to smooth the top surface. Anytime you have an overlap, there is the potential to trap moisture, which can lead to rusting. Sometimes on large panels the overlapped joints become visible when they are heated by the sun, since the double-thickness areas don't expand exactly like the single-thickness areas.
Q. I'm working on a 1937 Chevy pickup. My question is, when replacing a door skin with rust at the bottom, is it better to use a small patch, say 4 to 6 inches up from the bottom, or to replace the whole skin, welding an inch or so below the feature line? Also, is TIG preferable to MIG welding and should you always hammer and dolly as you weld? Thanks in advance for your advice.
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A.There are several approaches you could use to repair your door. Access to the back of a weld on a doorskin is often problematic because of the inner door panel, door bracing, and window mechanism, and the easier it is to reach the back of the weld, the easier it is to repair the distortion you'll get when welding. If placing the seam higher gives you better access, that's usually the better approach.
Nevertheless, you may be faced with choosing between having the welded seam near the center of the door, or closer to the feature line just under the window opening. There are advantages (and disadvantages) to each approach. It's often tricky to fold a new doorskin over the inner door panel and keep the door gaps uniform, and the larger the patch, the more challenging this is.
It's also true that if your weld is near the bodyline, the strength of the bead will go a long way toward lessening the distortion from welding. This is not to say that you'll get NO distortion near the bead, but the great strength of the beaded portion of the doorskin really helps to stabilize the metal in that area.
Welds made across a large, low-crown panel such as a doorskin are notoriously prone to huge distortion from the welding process, and they are quite difficult to get straight after they are welded! All things considered, if you already have a doorskin that's full-size, I'd probably recommend welding it into place just under the bead.
I prefer TIG welding, because it gives me a small, relatively soft, easy-to-work weld bead. Many people use MIG welding, partially because the equipment is less expensive, and MIG welding is easier for most people to learn, but there are some downsides. A MIG weld will require lots of grinding because of the large profile of the weld bead, and the MIG weld is considerably harder than a TIG weld, making it more difficult to work with a hammer and dolly.
For joints on high- or medium-crown panels, I usually weld the entire joint and then straighten with a hammer and dolly. On something as low-crown as a doorskin, it is sometimes better to weld small sections, then grind the weld flush, and work out the distortion with a hammer and dolly before welding a little more.
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