Removing rust is a chore, but the right tools can make the job a lot easier. One of the more aggressive ways to remove rust on a car is with an angle grinder. Using the correct combination of discs, you can remove the rust quickly and effectively while doing minimal damage.
Locate the rusted area on the vehicle that you want to clean.
Attach the 80-grit flap disc onto the angle grinder using the tools provided with the grinder. This 80-grit disc is fairly aggressive and should quickly take off the rust.
Place the safety glasses on your face, as dust and metal may start flying through the air.
Turn on the grinder and lightly start to grind the rust. It will start to kick up the rust and dust fairly quickly, so be fairly light on the trigger and the grinder so you don't go through the metal.
Grind the rust until a good portion of it is no longer visible. You don't want to damage the surrounding sheet metal.
Replace the 80-grit flap disc with the 120-grit flap disc using the tools provided with the grinder.
Sand the rusted area and surrounding area with the 120-grit flap disc. This will polish out some of the heavier scratches left in the metal from the 80-grit, as well as get out the rest of the rust.
Mask off the bare metal on the car using the masking tape and paper.
Spray the spray paint over the bare metal. Use a light coat at first, and then go heavier after the first coat dries. This will protect the car from future rust in that area.