The MGB GT undercarriage and the fender areas were well undercoated at some point with a very hard substance that is almost impossible to remove. Interestingly, areas like the frame rails don’t have this treatment. I’m guessing that whatever was used is partly a sound deadening product.
Areas like the frame rails have a light surface rust but fortunately no major issues. In most areas this comes off nicely with a brass wire wheel on my drill. There are some hard areas to get to however so I’m sure I’ll be doing some hand sanding and possibly be using my Dremel as well.
My goal is to get this area as clean as possible, spay the light rust areas with something like Ospho (if I can find it in Canada, might be too dangerous to have in this country!) and then get some primer on quickly. I’ll be spraying a heavy undercoating on to finish the area off.
Amazingly even the jack points are in really good shape. You hear so many stories of these being rusted out. I’m still very impressed with how rust free most of the MGB is, 50 years of oily goo isn’t that bad.