1967 Pontiac GTO Frame - All The Rage

A bead roller strengthens the panel and has the added benefit of preventing oil canning (what happens when you push on the middle of a pickle jar lid after the seal is broken, only on a larger scale). Obviously, there is a lot of test fitting that goes on with this type of work.

The third panel is, of course, the floor for the backseat and is made with two pieces just to make it easier, as MCR's Jim Hudson shows.

At this point, the floor needs to be raised up even with the rockers where it goes under the backseat. These two parts are plug welded together. A plug weld is produced by punching a small hole (can vary in size depending on the application, 1/4-inch is common) in the top piece of metal and then welding the bottom piece to the top through that hole, filling in the hole in the process. It's meant to simulate and/or replace a spot weld, but is much stronger due to the greater contact area of the weld.

The depth of the floor was made to approximate that of the original.

These next panels cover the area under the backseat and then follow the frame up and in between the wheel tubs. A small lip is folded under where it meets the tubs that will be plug welded to the inside of each tub. (An additional panel is also fabricated to fit between the tub and the fender lip and is plug welded in place to mimic the factory spot welds.) Where possible, all the panels are welded to the driveshaft-loop crossmembers or the inside part of the rocker panels. Nowhere is any of the floor welded to the frame, as that would prevent the removal of the body. Continuing on into the trunk is simply more of the same. Typically, with just mini-tubs, the Schwartz frame allows for a 345mm tire, but with full size tubs, Jeff can have pretty much any tire he desires.

All that remains are these two little panels just in front of the tubs.

In case you haven't noticed yet, part of the panel that was just installed needs to be removed in order to build the driveshaft tunnel. A long straight edge is used around the outside of the loops to mark the opening. Each tunnel section is simply formed around the driveshaft loops.

Here you can see the mock up of the driveshaft tunnel.

Originally, MCR mocked up a rounded trans hump, but later decided that a three-piece flat-sided version made the gas pedal placement much more comfortable. A cardboard pattern was made first and then transferred to the sheetmetal. With a solid-mounted engine, this trans isn't going to move much, so only minimal clearance is needed. It is critical though, that there is enough room for fluid lines or other needed connectors.

The trans hump will be plug welded to these 3/4-inch lips that have been added around the firewall opening.

When the parts are done being fitted, holes are punched around their perimeters so they can be plug welded in place. A professional seam sealer will later be applied to protect against water and other road debris.

We laid out all of the parts so you can see how they all relate to one another. Next issue, we will discuss the suspension and brakes and do a feature on the finished '67 GTO.