How to Replace Rusted Out Metal On A Car

by braniac

When dealing with rust on a car it is really just like you have always heard, that it works like a cancer and keeps eating away the metal unless you get rid of it. You can't just mask over it but have to remove it completely and replace the section with new sheet metal. This article is aimed at generally taking you through the steps of removing the old rusted metal and replacing with new 22 gauge sheet metal, which is a typical gage for general body repair for smaller panels and sections.

Rear Pass Side Quarter and Wheel Well Decay and Rust

Survey the damage and make a determination of the metal you need to cut out. Take your time and think it through before cutting away any metal and consider any bends you have to make. Sometimes you are best off to cut away additional metal if the cut will leave you on a flat area rather than a curved body line.

Rusted metal from the rear cut out

Put on your heavy work gloves before handling the metal along with safety glasses when using a cutting grinder. Cutting out the bad metal can be accomplished with metal snippers or possibly with your cutting grinder. This really depends on access. Survey the area behind your cut to be sure you won't be damaging another area of the car. Grind the cut out edges smooth with your grinder and clean the edges of the metal surrounding your cut out section with your wire brush, rust scuffer pad or sandpaper. You want at least 1 to 2 inches of clean metal surrounding the cut out areas and then spray the raw metal with the rust treatment spray.

Basic Metal snippers ansd 22 gage sheet metal

Form your new pieces with the sheet metal. If you do not have sheet metal bending tools you can be creative and use a standard vice on a work bench or the edge of a table to make a bend or use a dolly or anvil. You can also use steel plumbing pipe to form your metal over if you need a round type of bend. The 22 gaoge can actually be bent by hand to some extent as well.

Basic body repair hammers and dollies.

Special body repair hammers and dollies will help you shape and pound out your metal. The better you fabricate will mean less work later in the smoothing out stage using body filler.

Lower rail or rear quarter panel.

See the picture, new metal needs to be installed on both sides of the remaining lower section. In some cases it is easier to drill some pilot holes and use sheet metal screws rather than weld if the screw heads will not be seen. You can also use screws even if they are out in the open and then use your grinder to grind down the screw heads to below or flush with the surrounding surface. Welding is quicker, but you must have clean metal surfaces and reasonable access. Standard vice grips will usually work to hold the metal in place as you weld it or screw in place.

New metal spot welded and screwed in place.

Fill any gaps with liquid metal from a tube, JB Weld or epoxy after welding and then grinding down high spots, or if you used screws, and you have grinded down the heads flush to the surface. These products will also work well to fill in small holes.

New molding used as a guide.

Use the trim as a guide (as in this picture) to help you stay in proper contour. Always save any bad metal cut out to use as a guide before discarding.

Bondo, ready to mix and apply.

Use Bondo body filler to cover your welding seams after your metal is in place, level surfaces out and also for any final shaping or building up you may still need to do.

60 grit paper on power sander and bondo scraper tool for excess bondo

Use a scraping tool if needed to bring down any high or sharp spots from the hardened bondo and then use 60 grit sandpaper on a power sander to get your work as level and smooth as possible. Follow up with hand block sanding using 60 grit followed by 120 grit sand paper for further smoothing and leveling. Always wear a dust face mask when sanding or painting.

Almost there now!.

Spray high build primer to better see where you are at and then work with spot glazing compound for filling holes or cracks and also for minimal height building, applying in thin layers, allowing to dry between layers. Use a straight edge ruler to be sure your work is level and you can also use a second color of primer during block sanding for easy identification of low spots.

Tips

  • check You will get a smooth straight cut with the grinder versing your snippers, but sometimes you can't get proper access with the grinder where a snippers will allow you more movement.
  • check Allow Bondo to dry overnight before sanding down.
  • check Save any old metal you remove to serve as a guide in forming your new metal.
  • check Try to cut out metal in an area which will leave you a flat surface to work with rather than a body line curve.

Warnings

  • close Always wear proper gear when welding and grinding.
  • close Work in ventilated area.

Items you will need

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.