ALL PICTURES AND ACTIVITIES SHOWN AND DISCUSSED IN THIS POST THAT TRANSPIRED OUTSIDE THE BOUNDS OF MY HOUSE OCCURRED BEFORE I SELF QUARANTINED. Well “self” is a euphemism for my my wife and mother demanding that, given my underlying health conditions, I not leave the house. I’m going stir crazy, but the last thing that I need is those two opening a can of whoop ass because they thought I sneaked to Abe’s shop to have some welding done!
The front hoop is constructed from a single piece of 1.5” DOM with a flat top and constant radius bends on the sides. While this is easy to manufacture, it doesn’t closely follow the body which has a non-constant radius. If the interior isn’t finished, the hoop is noticeable, but not overpowering. However, when the interior is finished and the hoop is covered, the A-pillars overpower the interior. They’re not in keeping with the organic dash, tub, roof liner or door cards. In addition, the optional A-pillar covers don’t cover the hoop and require an extra 1/4” or so of fiberglass to be added.
Nice interiors are expensive and there’s a price point where it makes sense to modify the front hoop to reduce the size of the A-pillars. I’m not sure what that number is, but I’m aware of one SL-C with a $45k interior with massive A-pillars. That car should have had a modified front hoop.
The picture below shows how large the gap is between is between the front hoop and the body.
There’s two ways to shrink the A-pillars; (1) cut the front hoop off of the cage and fabricate a new one or (2) stretch the existing hoop. Note that it’s my understanding that Superlite has changed the way they manufacture the front hoop which makes it narrower. This would increase the need for the mod as well make the stretching approach infeasible.
In any event, I decided to stretch the hoop with a hydraulic jack. We started about one third of the way from the top of the hoop and worked our way down. Non-marring vice grips were clamped to the hoop to prevent the jack from slipping off. As the bottom of hoop expands the mounting plates lift off of the chassis and the outer edges pitch upward. At some point the outer edges of the mounting plates began to collide with the body. So I removed the body and trimmed the mounting plates with a cutoff wheel. I didn’t cut them off because they were useful to keep the jack from slipping off. The body was replaced, and additional stretching was done.
Once the right amount of stretch was achieved, the body was removed and the mounting plates were cut off with a portable band saw as close as possible above the weld. The bottom of the cut tubes were then trued up and made parallel to the chassis with a sanding wheel.
A new bottom plate was fabricated from 1/4” steel. There are two ways to fill the gap between the bottom of the hoop and the mounting plate: (1) machine a slug with a shoulder that slides into the hoop or (2) fabricate a pedestal for the hoop to sit on. Apparently it’s a common practice when fabricating cages inside of a car (i.e., one in which the roof can‘t be removed) to construct the cage shorter than needed so that the top joints can be welded in the car and the entire structure subsequently raised on pedestals. The pedestals seemed the easiest option, so that was the direction I took.
I fabricated two rectangular pedestals from 3/16” steel. No matter how I oriented the pedestals, the rear outer bolt holes on both sides were covered by the pedestal. Most builders could just relocate those holes, but I have removable side-impact bars which have tubes in the foot box that are welded to backing plates for the hoop, floor plates and the upper suspension mounting points. So, relocating those holes was a non-starter. The issue was solved by welding nuts, which will be located inside of the pedestals, to the top of the mounting plates.
Ratchet straps were used to tweak the location of the hoop and then everything was tack welded. With all of the changes to nose structure and suspension mounting points, I want to realign the suspension and body again before doing the final weld. The hoop isn’t as tight as I want, but it’s a huge improvement.
I had cut the dash to fit the old hoop and the white arrow in the pictures below illustrates how much the bottom of the hoop moved. Previously the fit to the dash was tight and now I have a lot of filling to do.
