A reverse-opening hood is not just a styling move. Once the hood load hangs off the front of the truck, the core support becomes part of the hinge system. That means sloppy linkage, weak mounting, or front-end deflection will show up fast in hood fit and operation. We built custom hinges, brackets, and core support spreaders to keep the structure where it belongs and to control the hinge path. The hinge geometry includes its own stop so the links do not roll over center, and the hood mounting gives us adjustment in three planes to line the panels up correctly. On this supercharged L5P build, we also mocked up the FEAD so accessory placement is fixed before sheet metal starts. The result is the access we wanted, with the structure and motion to make it work like it belongs there.
With Lockjaw nearing its trip out for sheet metal work, the team focused on finishing as many mock-up parts as possible and getting them installed in their intended positions. A major milestone was the first functional test of the custom reverse-opening hood hinges. The hinges had already been fabricated from quarter-inch plate and were intentionally overbuilt, but in their loose mock-up state they still needed a way to tie the mounting points together and control the assembly on the truck.
To solve that, a new bracket was quickly fabricated and tack-welded together. It used two existing bolt holes in the core support for the initial test fit, with additional bolt locations planned later to strengthen the installation. Once bolted in place, the hinge assembly immediately showed that the concept worked. Even with everything still hand-tight, without bearings or even washers installed, the geometry functioned as intended and the hood hinge moved through its arc cleanly.
The hinge design relied on geometry rather than a separate hard stop to prevent the links from going over center in the wrong direction. By arranging the links so they naturally locked into position at the end of travel, the team built a stop function directly into the mechanism. That meant the hinge could hold itself in the correct range of motion even in this rough mock-up form.
The initial success also confirmed that adding more fasteners to the core-support-side bracket would be worthwhile. At this stage only two factory holes were being used, but the team had already identified additional positions where bolts could pass through and make the structure much more rigid. That mattered because the reverse-opening hood would place substantial leverage on the front structure once the full hood weight was hanging from the hinges.
At the same time, the front engine accessory drive layout for the L5P was being finalized. Because the truck will use a Banks supercharger, the factory arrangement was no longer suitable, so a new FEAD mock-up was created to establish the final locations before the truck left for sheet metal work. The goal was not to build the finished engine package yet, but to lock in the positions of all major components so the surrounding fabrication could be designed correctly.
The mock-up included the new crank pulley and low-mounted accessories. An alternator was positioned in the new layout, and Vintage Air supplied a compact Sanden air-conditioning compressor that was mounted low as well. Its suction and discharge ports exited from the side, which should make hose routing easier and allow much of that plumbing to be hidden within the future sheet metal work. With the FEAD and hood hinges both mocked up, the front of the truck now carried a meaningful amount of weight, which exposed a structural problem in the core support.
Once the added weight was hanging off the front of the truck, the team found that the core support was deflecting enough to create tire interference. The factory inner fenders, which normally help locate the core support relative to the firewall, could not be used in their original form because of the new packaging. Even if they were retained, those panels are only light-gauge sheet metal and were never intended to act as major structural members.
That made it clear that a dedicated brace was needed between the firewall area and the core support. Without it, the hood hinges and eventual hood load would continue to pull on the front structure and allow movement. The team temporarily returned the suspension to droop and reinstalled the inner fenders long enough to capture reference measurements. Those dimensions established where the core support should sit, and from there they began designing what they referred to as core support spreaders.
The spreaders were first mocked up on the plasma cutter, then refined into a more permanent removable structure. Each side would ultimately use two pieces. On the cab side, a bracket landed near the firewall area. On the hinge side, another bracket overlaid the reverse-hinge bracket at the core support, effectively sandwiching that mounting area and tying the loads together. A final cap piece, cut from 14-gauge steel, would span the top and close the assembly.
The choice of 14-gauge material was deliberate. At roughly 0.075 inch nominal thickness, it was still thin enough to shape and manipulate, but thicker than 16- or 18-gauge sheet and therefore better suited to adding rigidity. The team built the parts around existing fixture tooling so they could maintain a consistent width and leave enough edge material to capture a proper weld. During tack-up, care had to be taken not to let the cap piece drift off line. The process was to tack, push the panel into contour, tack again, and continue along the shape until the overlay pulled itself into alignment. Once fully welded and blended, the finished part would resemble an organic tubular structure even though it was built from multiple formed pieces.
After both spreaders were installed, the improvement in front-end rigidity was immediate. The added bracing significantly shored up the core support and gave the hood hinge mounts a much more stable foundation. Just as important, it restored the necessary clearance. With the truck fully slammed, the team could now get a hand into the area under the hinge and confirm that the spacing they needed was present.
Although this extra fabrication had not been part of the original plan, it solved a problem that would have surfaced later anyway once the full hood was installed and the amount of deflection became obvious. It also gave the CAD work a reliable reference, especially for future air-filter-box design, because the front structure was now being held in the correct position rather than floating under load.
With the hinge side proven out, attention shifted to the brackets that would attach the hood itself to the reverse-opening hinge system. The first bracket was laid out, matched to its corresponding pieces, and tack-welded together for a trial fit. The team checked both bolt spacing and hood fitment before committing to final welding. The first side fit exactly as intended, validating the CAD model and confirming that the mirrored opposite side could be built with confidence.
These hood-side brackets used the existing holes from the original hood hinge locations, and nuts were welded to the back side of the doubler plates to simplify installation. After the initial mock-up fit, the brackets were removed again so studs could be welded to the back side. That change would make final assembly much easier: the hood could be lowered onto the hinge-side mounts with the studs protruding through, and then secured with nuts rather than trying to align loose bolts in a difficult position. Once both sides were completed, the brackets were installed on the hood and prepared for the full test on the truck.
The final installation was the key moment of the episode. With the brackets mounted to the hood and the hinges already on the truck, the hood was lifted into place and set onto the studs. Once secured, the team could finally test the complete reverse-opening motion. The hood opened smoothly on the first try, and the panel gaps looked remarkably close even before final adjustment. Despite the absence of the cowl piece, the alignment was clearly in the right range.
The hinge system was designed with adjustment in three planes. Fore-and-aft movement was handled through slotted angle brackets. Side-to-side adjustment was built into the star-shaped mounting plates on the underside of the hood. Up-and-down adjustment was located at the bracket mounted to the core support. That combination should allow the hood and surrounding body panels to be dialed in precisely once final bodywork progresses.
The motion itself was encouraging because the hood did not require much support during opening. The next planned refinement was an over-center spring. Rather than simply adding a spring that pushes in one direction, the team wanted a spring arrangement that would assist the hood during the initial opening, then pass across center and help control the motion as the hood came over the top. The hinges already incorporated mechanical stops, but the spring would prevent the hood from slamming into those stops at full travel. By the end of the test, the reverse-opening hood concept had moved from CAD and rough mock-up into a functioning mechanism on the truck, setting Lockjaw up for its next phase at Empire Fabrication.