Body straightening can be complicated and usually requires special equipment. Do not attempt body straightening unless you are a trained technician.
Make a complete analysis of the body structure condition before taking any steps to straighten the body structure. Analyzing the cause of failure will help to determine the correct sequence of steps in the repair. Use corrective procedures in order to reverse the flow of the damaging forces. In many instances, in order to reverse the flow of forces, you must apply pressure from different directions at the same time.
Careful use of controlled heat is critical. Too much heat, too little heat, or the improper application of heat is a major source of trouble. Heat the area that will be stretched as the frame is straightened. Heat the area after sufficient pressure has been exerted in order to cause a slight checking or silvery cracks to appear on the surface of the metal. Gradually increase the pressure while heating. Do not heat beyond 606°C (1200°F). A red glow indicates that the material is overheated. Overheating the material will cause distortion and stretching, as well as change the characteristics of the metal.