Removing signs from direct exposure from the elements will definitely help. But I can tell you as a materials scientist/chemist for over 30 years, if you are not going to remove the existing rust and then seal, coat etc the fresh metal, rust and corrosion will continue on some level. However, you can minimize these effects by using some climate control in your garage. The best, of course, would be putting in a dehumidifier to maintain lower humidity levels. It would further help if you can also control the temperature to prevent cycling.