We decided to replace the roof panel now as well, due to finding several rust holes along both front and rear glass channels, as well as some perforations above the doors. Replacing it - if done without warpage - can save time cutting and patching, save time, material and frustration of having to use filler to level all the welding work - and most importantly - allow us to repair and abate any rust issues that exist both on the underside of the roof panel, as well as on the support structure.
The easiest way to remove these panels is to first find the attachment points and then cut near them, but not on them - in order to remove the panel, exposing the areas that need to be separated:
A chunk of filler that was pushed into a rust hole the last time repairs were performed.
Definitely NOT the way to do it!
Heavy rust scale from both the roof panel and the structural panels:
The trimmings - removed by way of drilling out spot welds and separating the pieces with the air chisel:
After clean-up, we can see that some of the inner structure also needs to be repaired:
But first, any surface rust, hidden rust is converted and clean metal is prepped, using a phosphoric acid solution: