Versatile Rear Crossmember - We Gotcha Covered

Some people remember where they were when they heard Kennedy was shot. Others, when Neil Armstrong landed on the moon or the Dow hit 10,000. Me? I'm just a little bit different; I remember things like seeing my first Model A rear crossmember cover. Equal parts industrial chic, universal, and, most importantly, useful beyond merely covering a rear crossmember in the trunk of a car, I immediately fell in love. Never mind that it already had an intended purpose; I had to have that cover simply for the potential of what else it could be. In fact, I didn't even know what the thing was until I sidled up to the counter to buy it.

Despite building several cars in the half a dozen or so years I owned the thing, I never quite found the right use for it. For example, it seemed a bit too narrow for a tool tray yet too shallow for a spare-tire well. After inventing a few scenarios where I could use the thing-some of which required building a car around it-I finally resigned myself to the idea that the two of us weren't quite the match I initially thought.

But after seeing what Frank Wallic made for a crossmember cover, my heart is once again aflutter. It's not for the fact that he made his cover from lightweight aluminum or that he gave to it that neat aviation aesthetic, although I admit they're influential factors. No, it's mostly because Frank's idea has great versatility. For example, while he copied the Ford part's general design, he wasn't necessarily locked into its dimensions. Change the size and orient the rivets to suit the application, and it'd make a dandy heater or A/C plenum housing, or, perfect for my current car's application, a blister to cover the hole made in my trunk's floor to accommodate the axlehousing. Need to relieve the firewall for a distributor but don't want to recess the whole thing? Scale this sucker down to fist sized and you're good to go, Jack.

The other element to this article's appeal is its user friendliness. Don't have a sheetmetal brake? No problem; most shops-think HVAC vendors, even-will cut and fold the parts and shrink edges for a small charge. Lack the tools to set solid rivets and don't like the look of blind rivets? Why not use small slotted stainless #8 or #10 round- or truss-head screws and brass nuts instead?

Point being, this is one of those projects that's as simple as you need yet as complicated as you wish. For those reasons-and also for the fact that this is a project within even my scope-I'm filing this memory somewhere between the first space shuttle flight and the advent of the personal

While the cover Frank made was intended to replace a bona-fide Model A part, the stock part didn't match the aircraft aesthetic of the battery box, seat risers, fuel tank, and other various parts in Editor Brennan's roadster pickup.	Frank started by measuring the cover's overall dimensions. Note that the finished product will have sharper radii than the original. The new cover's top radius, for example, is sharper than the original's, which ultimately offers more room.	With the general dimensions plotted, Frank brake-bent a few lengths of 2-inch-wide aluminum strips. Incidentally, he's using the same 16-gauge aluminum sheet he uses for his other projects.
The lines from the last step represent the centerlines of each radius in the angles. To create those radii, Frank uses a mechanical shrinker like the ones available from Aircraft Spruce or Williams Lowbuck Tools.	The angled strips take on a compound shape after a few strikes in the shrinker jaws. For what it's worth, the key to achieving a gentle radius is numerous light strikes over a greater area rather than a few heavy ones in one spot.	If you've bored multiple holes in any material, you understand that a drill is seldom the right way; they skate and consume eons of time at best, whereas the simplest punches do the trick-precisely, at that-in one strike.
With the edges formed, Frank created the sides. In this case, they're little more than a simple shape with one bend, but there's a hidden pitfall in that single bend if you're not careful. You see, each flange end needs to be cut at a 135-degree angle if the flanges are to meet perfectly.	Using the edge flange as a guide, Frank bored the holes in the side panel. Tip: Don't drill all of the holes at once and expect the rivets to fit.	Remember our instruction to cut the flanged edges at 135 degrees from the edges? Well here's what we're talking about. Note how the top panel's sides are all 90 degrees to each other and how the 135-degree edges protrude from them.
Once again, Frank riveted together the parts-this time the top panel to the flange. Note the even fit at the corners.	As he did for the edges of the seat risers, Frank made L-shaped gussets to tie together the corners. He laid out and drilled his pattern on the gussets and finally drilled the flanges using the gussets as guides.	While it's entirely a luxury, Frank used his pneumatic rivet squeezer to form the rivets at the edges. Considering that the panel may need to sit flush on a floor, you may consider countersinking the bottom side of the lower edge and using flush rivets.
The top of this cover will sport its own doubler plate just as the top and sides of the battery box feature them. Rather than tediously measuring the pattern, Frank uses a rivet fan spacing tool.	Proving there's no kill like overkill, Frank quite liberally peppered the doubler plate. Work? You bet, but the final result looks quite intense.	And here we have it: a crossmember cover that's equal parts form and function. More than that, with careful tuning and resizing it's a part that has greater potential than Ford's one-size-fits-all design.