How do you weld a seam that is almost invisible on your body panel? Take some time to make your replacement patch a perfect fit. Ideally, there should only be a 1/32″ (or less) gap between the patch and the body panel. Place the welding tip wire through the gap and tack-weld the patch in place (put a couple of small spots of weld here and there). This holds the patch in the correct position. Next, begin welding a small portion at a time (1/2″ to 1″ usually works the best). Be careful not to weld too much at once, as this would warp the body panel.
Once the welding is complete, carefully grind the welds flush with the existing body panel. Further welding may be required to fill the areas that were missed. Wire feed welding is a good weld for beginners to try. Try practicing on a piece of scrap body panel before attempting to weld your body panel.
Tip: when purchasing a wire feed welder, make sure it’s a name brand and purchase the welder set-up that uses the argon gas rather than flux core wire. Gas aided welding is much smoother and user-friendly. It’s a little more costly, but well worth the investment.
Unibody panels need to be replaced when they are rusted or damaged. After spot weld drilling and panel cutting is complete, it is time to begin fitting the replacement panel. This guide will apply to most panel replacements, including roof skins, rear quarter panels or patches, floor pans, cowling vent, taillight panel and trunk floor. It will take you through the steps of replacing a panel.
- Dolly (a variable shaped iron straightening tool)
- Drill or Air Punch
- Clamps and Vice Grips
- Sheet Metal Screws
- Impact Driver
Body Panel Replacement Process
- Drill all spot welds and remove the old panel. For further information on this step, please see our guides on Locating Spot Welds for a Unibody Panel Replacement and Drilling Spot Welds for a Unibody Panel Replacement.
- Use the hammer and dolly to insure all flanges are flat and free of distortion. This can be done by placing the dolly on one side of the flange and hitting it with the hammer from the other side of the flange. This will straighten the flange.
- Using a grinder, grind all excess spot weld bits and pieces smooth.
- Next, fit the replacement panel in place. Some panels require slight trimming or slight reshaping, depending on the reproduction panel. This is done with shears and/or grinder for trimming and hammer and dolly for reshaping. NOS parts fit the best with minimal reshaping, but are not readily available.
- Once the panel has been nipped and tucked and fits reasonably well, clamp it into place using vice grips, C-clamps or sheet metal screws. Helpful tip: if you are installing sheet metal screws to hold the panel in place, an impact driver is a big help.
- Look at the panel very carefully and mark any areas that need additional fitting work. Rework these areas as necessary.
- Once you are satisfied with the fit, remove the panel and drill or air punch holes in the replacement panel every few inches on the weld flanges (the new areas that will be drilled will be similar to where the old panel’s spot welds were drilled).
- Re-clamp the panel in place.
- Next, begin to weld the panel in place. Use the plug weld method, in which you weld through the hole of the new replacement panel, filling the hole which attaches it to the backing flange.
- After welding is complete, grind any excess weld buildup. The welds should be flush with the new panel. If you installed sheet metal screws to hold the panel in place, remove them now and then weld the holes shut. Grind these welds flush also.
- Replacement is now complete and ready for any refinishing that you desire.
Copyright 2007: FastbackStack, LLC
Drilling spot welds is an important step of the body panel replacement restoration process. But, often times spot welds are difficult to locate. Perhaps the vehicle is severely rusted or perhaps it has been painted several times. Both rust and paint can cover up spot welds. This guide will give some tips on how to locate seemingly invisible spot welds.
Course Sand Paper: 40 grit or lower
- Wire Brush
- Flat Metal Chisel
Tips for locating spot welds
Spot welds can be covered with rust or paint. Use these tips for finding them:
- By hand, run course sandpaper over welded flange areas a few times. This will remove rust and/or paint along the flanged areas but will leave traces of paint and/or rust within the low areas. These low areas are the spot welds.
- Run a wire brush over the welded area a few times. This will yield similar results as using sandpaper. The rust and/or paint along the flanged areas will remain and traces of rust and/or paint will remain within the low areas, or spot weld areas.
- In a dim-lit setting, shine a flashlight at a very low angle along the welded flange. Doing so will, in some cases, cast a shadow at each spot weld. Then, mark this area with chalk.
Most spot welds are discovered by using the previously described methods. In case there are additional welds that are undetected, try this tip:
- Using your hammer and chisel, begin to remove the panel by laying the flat edge of the chisel between the panels and gently hammering until the chisel comes to a stop. Often times, it is hitting the spot weld.
Now that you have located all of the spot welds, you are ready to drill the spot welds. Please see our guides on Drilling Spot Welds for a Unibody Panel Replacement and Unibody Panel Replacement for more helpful tips.
Copyright 2007: FastbackStack, LLC