If you bend a frame rail in a composite structure, you have x new welds you have to perform, y rivets, z bolts, w plastic pins and spacers. Some of those attac

If you bend a frame rail in a composite structure, you have x new welds you have to perform, y rivets, z bolts, w plastic pins and spacers. Some of those attachments were not designed to be removed and performed again, so you're looking at removing and replacing otherwise okay parts and then probably realizing that some other piece is slightly out of alignment and can't safely be reused... If you bend a a unibody casting, firstly there is a larger chance that it is non-critical since there is so much added mass and structure. It is not a series of dominos like in a composite. Secondly, all the attachment points are cast into the part. Replacement of one large piece is a significant reduction in effort, and results in more confidence in the ultimate repair.