Hot Rod Crossmember Suspension Upgrades - The X Factor

Again looking from "underneath", I welded the spacer plate to the side 'rails. I'll make a removable curved bolt-in plate for the top side of the crossemember, which will also act as a safety loop to stop the driveshaft from ever coming up through the floor, as this is where the driveshaft's front U-joint will be.

Still with the jig upside-down, I welded the underside of each side 'rail where it joins the main 'rails, as well as welding the underside of the cross tube to the chassis and side 'rails. If you have to weld upside-down with a MIG, turn the wire speed up a little to stop the weld from forming a ball and falling to the floor.

Here's how the Super X side 'rails join the main chassis 'rails at the rear, and one of the reasons I moved the assembly rearward slightly. The vertical weld at the joint aligns with the kick-up, looking neater and adding strength in this area as it's welded to the boxing plate, which bridges the two welded sections of chassis 'rail.

Voilà! The finished frame. Well, almost, as the front section still needs to be boxed once I decide what I'm going to do with the front crossmember, and I still have to weld in the side braces. I'll fabricate a copy of the righthand brace to match for the left side of the chassis once I've determined where the master cylinder will mount. Once the monotonous task of boxing the stock frame was completed, the Super X installation only took a couple of hours and transforms the rigidity of the chassis.

With the chassis brought back to my home garage I could fit the rear axle and trial fit the (dummy) motor and trans. I was pleased with the drop-in ride height afforded by Z'ing the chassis.

The main reason for installing the trans was to illustrate how with a little trimming of the curved section of the center spacer plate, I'll be able to remove the trans from below the car. Note I only tacked the section of cross tube I'd removed in place as I neither like the appearance of it nor am I positive yet that it won't be in the way. This way it can be easily removed or fully welded.

Though it's not part of the Super X installation, I thought I'd show how I finished off the rear of the main 'rails. A stock Model A chassis uses a pair of triangular plates riveted to the 'rails and rear crossmember where they join. I could have just boxed these in with 1/8-inch plate but wanted to retain the stock appearance as much as possible, as this area will be seen on the finished car. The lower plate is larger than the upper, so I bent up a filler piece that was butt welded to the edge of the upper, but was welded slightly inboard on the lower. I also retained the stock rivets. Boxing this area in this way will provide extra strength without making it look like a triangular piece of box section was welded into the corner!