Using heat and cold is an advanced technique for straightening metal. In the early days of automobile manufacturing panels were rarely complete straight even when a vehicle was new. It wasn't until more advanced processes for shaping metal came about in the 60s and 70s that panels were more reliably even and straight. Click on continue reading to see how we use heating and cooling metal to straighten the door panel on this pickup truck.
The panel below is a great example of what was common in manufacturing in the 20s-50s. Although steel panels were a huge improvement over wood, it was not easy to get body panels to be perfectly flat. Of course, there is also damage and years of wear and tear that can occur. Notice that the panel below is not damaged, but clearly it is not flat when we hold it up to a straight edge.
We apply heat to small points which stretches the metal a little. Then we rapidly cool it to shrink it and allow us to flatten the panel. Of course we will follow this with a very thin coat of body filler. Keep in mind that body filler cannot exceed 1/4 inch, and we preferred to use much less than that. Body filler in not a replacement for high quality metal work. It is just another tool in the arsenal of a really good body man.
When this truck is finished it will that that elusive laser straight body.