To repair a damaged car frame, straighten the frame back into position using hydraulic push and pull rams, or weld straight metal pieces into the frame if necessary. If you don't have experience repairing car frames, take the car to an auto body repair shop, as repairing frame damage is a difficult process that leads to safety and performance issues when done incorrectly.
To straighten a car frame, you must determine the proper alignment for the parts you're straightening. Auto body shops typically use computerized tools, ultrasound technology and lasers to determine the correct alignment. Once you have the alignment information, use the rams to straighten the frame into that position. To weld a car frame, cut out the damaged pieces of the frame and replace them with straight metal pieces.
If you don't repair the frame correctly, it may not be structurally sound, and therefore doesn't offer the same impact protection as before. This issue occurs when straightening or welding the frame, but it's most common with welding, as any metal piece that isn't welded in precisely doesn't offer adequate protection. Wheel alignment issues are also a result of improper frame repair.
If the cost of repairing the car exceeds a certain percentage of the car's current market value, the insurance company may declare it a total loss. In this case, the insurance company typically pays the owner the car's market value, although this varies depending on the company and the driver's insurance policy.