Expanding on Post #91, my plan was to replace the poorly installed metal C-pillars with seamless high strength tubes tied structurally into the chassis. They will enhance the rollover protection, increase the bending stiffness of the chassis, and provide a framework to install the quarter and rear windows. Here's the plan for the C-pillars once again:
To make the C-pillars, I chose 1" OD x 0.120" wall DOM tubing. To arch over the quarter windows without interference, the tubes had to be formed with slight curvatures at either end. The hydraulic pipe bender was very helpful for this since DOM tubing is very rigid and the tube lengths were relatively short. Using the 1" diameter die and the rollers set rather close together, I made several prototype pillars with cheap electrical conduit first, then repeated the best process with the expensive stuff:
The pillars needed to be bent in two planes: downward, and also inward slightly, making compound curves (though not visible in this photo):
I dry fitted them to check that they both slid into the upper door frame channel and that they sat on the chassis at the same height and location:
Here's a close up of the top end of the driver's side pillar showing how it rather neatly slid into the stock OEM roof channel:
I left the tubes long enough to slide 4" into the roof channel (the silver line indicates the end of the tube). Once clamped in position, I drilled a series of 5/16" holes through the OEM steel to gain access to the tube hiding inside:
Then I rosette welded the tube to the channel in five spots through the holes. I'll return to this area later to weld the inner and outer roof skins to the tube as well, but they weren't quite ready yet:
With the tops secured, I turned to the bottom ends of the C-pillars. I mocked up the lower window frame to be certain I left enough room between the pillars for it:
Then I removed the lower window frame and put a bead around the base of both tubes:
I ground a couple notches in the aft-most legs of the window frame to clear the new weld beads at the base of the pillars, then welded the window frame in place as well:
From inside the cabin, I stitch welded the forward base of the window frame to the cross car beam at the top of the firewall. It isn't obvious in the photo, but the cross car beam isn't flat. It bows upward toward the middle, which explains why the welds don't extend beyond the centre two feet:
Finally, I refitted the rear window and started brainstorming how to fill in the gaps between the C-pillars, the roof, and the window: