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1948 Cadillac Sedan Bumper Guard Removal - Leaving A Custom Cadillac UnguardedFrom the December, 2011 issue of Rod & Custom By “Rotten” Rodney Bauman
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“You can’t teach an old dog new tricks,” or so it’s been said. While I don’t buy that in its entirety, I’ll agree that we’re less likely to learn new tricks while working alone as opposed to working with others. Recently, I had an opportunity to work closely with the expert metalmen of Hot Rods & Hobbies in Signal Hill, California. There, under custom reconstruction, is a stately ’48 Cadillac sedan. With its roof lowered an appropriate 2 inches, there is no interruption to the Caddy’s inborn bulbous flow—it’s working. Now some may be thinking that a chop of such short proportions is mild, and therefore would not require as much head scratchin’ as a more radical chop. But let us assure you, for the curvaceous Cad, with its detachable post hardtop conversion, 2 inches did not come easily. To get this project started,... To get this project started, Andrew “Surge” McClelland discards the guards. This is where we get our first glimpse of what must be dealt with, now that factory-misaligned bumper sections and unsightly indentations are exposed. Because you can’t identify every wave or ripple with the naked eye alone, McClelland gives the bumper a “feel”. Along the same lines it should also be noted that the smaller detail refinements don’t necessarily come easily, either. Take the deletion of the factory bumper guards, for example. Here in the real world, the seemingly subtle smoothing of this Caddy’s lumpy bumpers will require more than the ol’ proverbial “shave”, as it’s called. On this car, the factory’s stampings, as you’ll see, have seams and large indentations concealed beneath the guards. Short of its supporting bracketry, this type of bumper is comprised of five major components: a center (also referred to as a face bar), two large ends, and, of course a pair of large, in-your-face guards. While they do “guard” the bumper from impending peril, to some degree, the prominent protrusions have a downplayed secondary function, which is to create a visual distraction as they cover up the ugly truth lurking below. Because the guards are where your eyes go, you’ll not focus on the fact that the three welded-together horizontal sections of the bumper don’t even line up with one-another. Well, all of that is about to change.  Next, bumper meets poster...  Next, bumper meets poster board and an outline of its current shape is drawn before any cutting or welding begins. With a top and bottom edge outline recorded and saved, reference marks are made in places where McClelland anticipates unwanted shape changes could occur. These steps will prove their importance later on.  Although we have an extra...  Although we have an extra bumper to be used as a metal donor, it’s also been used as a bumper—in the literal sense. The ’48 Cadillac bumpers also varied in shape from the factory, therefore we have no truly matching sections to choose from. Before any marks for incisions are made, McClelland hunts as necessary for the sections of metal that bear the most resemblance.  In order to prevent the loss...  In order to prevent the loss of this bumper’s overall shape, bracing will be necessary. With 1/2-inch tubing welded from the base of the jig to the outer edge of the bumper and at each intersection in-between, this substantial structure should hold the pieces in their places.  By the time the mark for the...  By the time the mark for the first cut is made, McClelland knows exactly where he’s going. Here we can clearly see the first section to be removed. Given the precautions taken, will the bumper spring out of shape once it’s cut? McClelland tells us that as a fabricator, he’s learned to expect the worst—that way he’s prepared for anything.  Just prior to making the first...  Just prior to making the first cut, McClelland explains how reciprocating saws don’t cut straight. This 3-inch extended-reach pneumatic cutoff tool certainly does, however. This cool tool is now available at Harbor Freight—so I went out and purchased my own right away.  Then with a half-round bastard...  Then with a half-round bastard file, McClelland takes the cleanup a step further. Both the insides and outsides of these fresh-cut edges are receiving equal attention.  It’s time to select a section...  It’s time to select a section from the metal donor bumper, and this is not the last time you’ll see a profile gauge in action here.  As we’ve said before, ’48...  As we’ve said before, ’48 Cadillac bumpers varied in shape from the factory. This is the closest-in-shape area to be found on the metal donor bumper.  And away we go again with...  And away we go again with the aforementioned cool tool, as the section of selection is going where it’s needed the most. At first, the replacement sections will be sliced slightly wider than the initial cuts in the bumper to be used.  Straight from the metal donor...  Straight from the metal donor bumper that’s the way it fits. Obviously, it’s not a perfect match, but Dr. McClelland is in—and his transplants are rarely rejected.  Several different hammers...  Several different hammers and dollies will be used as McClelland begins blending the contradictory metal shapes together. Taking care not to stretch the metal, McClelland has chosen a soft copper hammer for this phase. The horizontal scribes indicate a high ridge that needs to be worked down.  At McClelland’s well-equipped...  At McClelland’s well-equipped rolling workbench, equal attention is paid to the patch portion from the metal donor bumper—first on a small anvil. Then follows some fine finessing—still using the copper hammer, but this time in conjunction with a soft lead shot bag as a softer backup dolly.  And once again, a profile...  And once again, a profile gauge comes into play. This reading tells us that the ridge is coming down, but still has a ways to go.  The blending of these metal...  The blending of these metal shapes could also be described as a splitting of their differences. Although they’re getting closer, these parts still need work. Here McClelland has chosen a “proper G-clamp” to secure a slight spread.  Meanwhile, back at the bench,...  Meanwhile, back at the bench, the peak portion of our patch is in need of some sharpening. A shot bag and a handle dolly are used for this bit of reshaping.  Following his own instructions...  Following his own instructions in accordance with earlier-made scribe lines, the patch undergoes many fit-checks before any final trimming or tack-welding takes place. At this point, McClelland is pleased enough with the fit he’s worked for. Remember that earlier the patch was intentionally cut wider than the gap it will fill—hence the overlap.  With a blue layout fluid applied...  With a blue layout fluid applied to the backside of the patch, the patch is held firmly in position as scribes for trimming are made. These guidelines are exact, and will be visible enough to follow during the next crucial step.  After the cuts are made, the...  After the cuts are made, the edges are dressed down the same as they were on the bumper earlier. What looks like an excellent fit to me, and might also to you, is under intense scrutiny by McClelland.  Before any welding preparations...  Before any welding preparations are made, the blended shapes are checked for both accuracy and consistency.  The swiveling magnets being...  The swiveling magnets being used here firmly position the patch, and combined with clamps at the bumper’s edge the soon-to-be tack-welded patch has nowhere to go. Note that the copper plating has been removed on both pieces to avoid any potential contamination during welding.  After dressing the edges (including...  After dressing the edges (including beveling each side to provide a V-groove for optimal weld penetration), McClelland TIGs the patch with his trusty Miller Dynasty 200 in small increments, checking the bumper and donor metal’s relationship as he goes.  Immediately after the patch...  Immediately after the patch is attached, the levels and shapes of the sections being joined are rechecked for trueness. Now, according to McClelland’s straightedge, just below what was the high spot is a low spot looking for a place to happen.  For the hammer-on-dolly work...  For the hammer-on-dolly work needed to shrink not stretch the aforementioned high spot, McClelland uses a soft brass hammer. But, as we’ve said before, elements like brass and copper will almost certainly contaminate the forthcoming welds. So, a wire wheel is employed to remove any captive fragments of brass.  Now it’s back to the ol’ grind....  Now it’s back to the ol’ grind. Once again beginning with a 2-inch Roloc abrasive disc, the sparks begin to fly, as the welds get dressed.  Now onto a few holes remaining...  Now onto a few holes remaining in the bumper’s centersection where a license plate bracket once attached. First, the holes are drilled to ensure that they’re truly round. Then the unwanted holes are countersunk on both sides as necessary for soon-to-be patches to achieve full penetration when welded in. And as we’ve seen before, the copper must be ground away before any welding success can be expected.  Backed up by an appropriately...  Backed up by an appropriately shaped dolly, a fabricated plug assumes its position. It only takes a few gentle taps before it fits in snug and holds itself in place without clamps or magnets. These small-by-comparison patches will receive no less attention than the larger ones have. Again, the straightedge is used to confirm that we’re ready to weld.  Leading up to each weld as...  Leading up to each weld as we’ve seen, McClelland prefers to spend his time on proper fit and setup, rather than fixing problems that occur as a result of rushing through.  At first a 2-inch Roloc disc...  At first a 2-inch Roloc disc is used to dress down only the highest spots of the new weld—much like what we’ve seen done on the larger patches. Then, while wielding a flat bastard file, McClelland explains that ideally, these welds should be just one tad higher than the metal they join. That way they’re easily ground and filed flush.  Now doesn’t that look better...  Now doesn’t that look better without misaligned seams and unsightly indentations? With nothing left to hide, this ol’ bumper is no longer dependent upon the visual distraction of the guards.  At this point, there are just...  At this point, there are just under 30 hours invested. Next McClelland will fine-tune the still-sharp edges, thus leaving the smoothed-and-improved bumper unguarded and ready for the next lengthy process at the chrome shop.
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