With the engine running sucessfully, it was back to dealing with the rust. With the car stripped down to the frame, it was obvious that a lot of repair was in the works.
Here is what the frame looks like. Under the skin, there are two side rails and an internal X frame.
At first glance the lower skin of the frame looked good but a closer look showed pinholes all along the x-frame that lies beneath the skin , plus there was a rotten rear flange, and pieces rusted off the edges of the frame. Because the lower skin was in such poor condition I was afraid of what lurked underneath. So I opted to remove the rear half of the lower skin.
The standard practice for this is to locate the spot welds and drill them out. But no luck here because the welds were not visible even after wire-brushing the lower skin. Usually, this shows their location. Also the edges of the lower skin had been welded as part of a previous repair. So this task turned into to very fine surgery.
I have to say that whoever did the welds on the previous repair is a damned fine welder. The welds are of the highest quality without so much as even one blemish.
So, first I cut triangles out of the lower skin so I could locate the x-frame and the frame rails beneath the lower skin. I goofed in a couple of spots and nicked the rails and the x-frame, but those spots were rotten and had to be replaced anyway. So once the interior bits were located, I drew them on the outside of the skin and cut out more of the skin. Then there was only one way to remove what remained welded to the innards of the frame- that was to grind away the skin inch by inch until I had removed all of the skin stuck to the frame. What a job! Two wheels for the angle-grinder and 7 hours later, the skin was off.
With the lower skin off, I found the rear flange beyond repair, parts of the flange on the x-frame were pooched, as were 40% of edges of the frame, and the floor of the box section at the front of the frame was toast. However the top skin of the frame and the upper surfaces of the frame rails and internal x-frame are just fine.
At this point, I felt like giving up. Option 1 was to buy a new frame. But buying and shipping a frame to Canada is beyond my means. After paying for shipping, customs duties, the total is over $2,500 Canadian. Option 2 was to replicate the frame but this requires access to an 8-foot sheet metal break and a similar sized shear. Since I have access to neither it was Option 3 – fix the frame or bust.
First, I cut and welded into place most of the rear flange. Here is the new one About 3/4 of the old flange was pinholed or missing, so most of what you see is new. This entire work requires a very very delicate hand with the MIG.
The key is low voltage, low feed, angling the gun steeply and stitch welding very slowly, allowing the weld to cool between each stitch. In places, the metal of the vertical section is now paper-thin, so I did blow through a coupe of times and had to weld holes shut.
The dogleg that joins the frame rails to the x-frame inside the chassis had a chunk missing out of it. Here is the new dogleg welded into place.
Part of the flanges of the inner x-frame were totally done, so I cut 14″ of new flanges and welded them in place. Here is the result.
The next thing was to reskin the underside of the front box section. This is solid now, but I am not happy with the result. The upper surface of the skin has lumps along the edge and when I weld the new skin over it, it may ripple. At this point, I am contemplating ripping the new skin off, bending up a new u-shaped hunk of 18 AWG, then welding it into place. Here is the current repair to the box section.