When a car has extensive rust damage, the spot may need to be cut out and replaced with a new panel. This is a time-consuming task that requires completing every step precisely if the final result is to be successful.
1. Mark off the section you are going to remove with a permanent marker. Cut this section out using an angle grinder. Once this is complete, take the section you just removed and trace around it on the new panel, leaving around ¾” in diameter on all sides. Cut this section out in the same manner.
2. Use flange pliers to create a ridge around the outside of the new panel. This is important, because this ridge provides an area for you to weld this section onto your car with.
3. Sand the area around the cutout to about three or four inches away from the cut you have made. Go all the way down to the bare metal if at all possible. The best tool for performing this sanding operation is an orbital sander and 80-grit sandpaper. Once the area is completely sanded, vacuum or brush away any dust that is remaining.
4. Attach the new rust panel to the appropriate spot by using c-clamps to help hold it into position. Make sure the edges of the new panel are flush with the perimeter of the old one in order to ensure the finished product will appear smooth.
5. Use tack welds to hold the new panel into position. Tack welds are defined as a number of smaller welds that are placed a reasonable distance apart. Once you have “tacked” the new panel on, go back and make a series of longer welds between the original tack welds in order to firmly secure the new panel. These should be around one inch long, as longer ones could cause the new metal panel to warp. Take your time when making these welds and allow the metal to cool completely between each one.
6. Allow the metal to cool after welding and then sand any uneven edges lightly. If possible, do this by hand so as not to take off too much of your new metal. Remove any residue left from your sanding efforts before applying primer and paint.
7. Apply one coat of automotive primer onto the new panel. When doing so, be sure to mark off the area surrounding this panel so that primer does not get onto other surfaces. After the first coat has dried completely, sand it lightly and then apply a second coat.
8. Add a coat of touch-up paint to your rust panel. Two or more coats may be needed in order to fully cover the exposed primer. If so, allow plenty of time to dry between each one.
When rust panels are installed properly, others will be virtually unable to tell this work was performed. Best of all, you’ll help your vehicle maintain its value while saving money on having a professional perform this work for you.