Ever since the beginning of time man has pondered the age-old question of how to bond fiberglass to steel without having it crack in no time like an egg dropped from the cab of a lifted truck traversing a rocky road across the plains of Montana. OK, so I exaggerated a little, but you guys get the point: it's pretty tough to successfully bond fiberglass to steel without having it crack and separate.
The subject vehicle of this tech story is the '72 Ford F-100 shortbed Styleside I'm building to compete against Classic Trucks' associate editor Grant Peterson and his '68 F-100. Since the build-off began a few things have changed, but the look that I'm seeking for mine has not changed one bit. I'm building a Gasser-styled truck and there's no two ways about it. Second in line to the truck's lifted Gasser stance is the Ford Thunderbolt-styled bubbled hoodscoop I'm using to give my truck the ominous appearance of a mid-'60s Ford factory-built dragster. The original bubbled hood that concealed a 427-inch 425hp Ford FE big-block engine in the '64 Ford Thunderbolt Fairlane was made entirely of fiberglass.
Only one Thunderbolt was built in '63, followed by 100 in '64, and two in '65. Then Thunderbolt production ceased forever. However, the badass looking teardrop shape inspired an aftermarket trend that lasted for at least another decade. When it came time for me to track the source of a fiberglass hood bubble for my F-100 I didn't have real high hopes of being able to just go and buy one off the shelf. I figured the odds of locating an NOS part would be slim to none. Then in the summer of 2007, while on Americruise touring Speedway Motors' giant facility in Lincoln, Nebraska, I witnessed some of the guys in Speedway's fiberglass manufacturing plant laying up some fiberglass parts by hand and the notion struck me that perhaps Speedway might be able to help me. Sure enough, the reverse teardrop hoodscoop that Speedway fashioned directly after a Ford Thunderbolt hood bubble back in the '60s was still available. The guys at Speedway Motors told me this design was done on a made-to-order basis, and would take about six to eight weeks to deliver. It couldn't have been more than two weeks after I ordered the Thunderbolt hood bubble from Speedway that the freshly manufactured fiberglass part arrived in a cardboard box at my front door.
Although I was anxious to get started on mounting the bubble to my hood there were some negative things I remembered about putting a fiberglass hoodscoop onto a steel hood. The first images that came to mind as I reminisced about the hoods I had seen done back in the '60s and '70s were grotesquely deformed, or at the very least cracked. The worst mistake made while trying to mount a 'glass hoodscoop was to use pop rivets, and then attempt to feather them in with Bondo. On the other end of the spectrum, there were the guys who did a really nice job of molding the 'glass scoop onto the hood, but it was only a matter of time before the fiberglass and the steel would delaminate, and then it was back to square one.

Second from the top we will...

Second from the top we will be using SEM's Dual-Mix Weld-Bond adhesive to cure the age-old problem of fiberglass delaminating from steel.

Here's the stock '72 F-100...

Here's the stock '72 F-100 hood complete with 34 years worth of dents acquired during its former life in Dunsmuir, California--first as a milk delivery truck, and then lastly as a firewood hauler up and around Mt. Shasta. I bought the truck in 2006, and the rest is history.
There has been a lot of suspense building as the two bumpsides near completion. I'm sure when Grant and I finally pull up to the showdown both of our trucks are going to be scrutinized down to the very last detail. With this in mind, I knew that one of the last things I wanted to have happen was to roll up to the showgrounds with big stress cracks appearing on my hood. The next step was to call in the big guns and find out if there was any new technology on the market that could minimize the possibility of an embarrassing failure. Sure enough, when I called Tom Prewitt at Resurrection Customs & Hot Rods in Fullerton, California, he informed me that SEM Products had an entire line of heavy-duty adhesives intended specifically to address a hybrid project like I was about to undertake.
The first thing I did when the Thunderbolt scoop arrived from Speedway Motors was to immediately remove it from the box and place it on top of my '72's hood to see how it looked and note any alterations that would be needed to make it fit properly. For the most part, the Thunderbolt scoop lies perfectly flat--until one looks at the front of the F-100 hood, where it is shorter than a car hood with the curvature descending faster. In order to make sure the Thunderbolt scoop looks right on a '67-'72 F-100 hood it was necessary to cut out the raised steel center section that vaguely resembles a T-Bird hoodscoop, and then fabricate new sheetmetal.
As we are dealing with body-working both steel and fiberglass, we will cover steel in this issue and cover the fiberglass portion in next month's issue. CCT

Before preparing the hood...

Before preparing the hood to accept the Speedway Motors Thunderbolt hoodscoop, it was necessary to pound out the dents. Resurrection Customs & Hot Rod's metal finisher, Matt Means, started on the top of the hood and then flipped it over to reach the underside.

Matt stated that a person...

Matt stated that a person has to be real careful not to grind the sheetmetal to thin while running the grinder over the crown of the dent.

The Thunderbolt scoop was...

The Thunderbolt scoop was placed exactly where I wanted to have it mounted and then a pattern was drawn around it with a Sharpie. Matt then ground the paint down to the bare metal in a wide swath.

Matt metal-worked out most...

Matt metal-worked out most of the heavy dents before he was ready to cut out the offending portion of the stock hood, the part that wouldn't allow the Thunderbolt scoop to sit flat.

Matt used a 4-inch cut-off...

Matt used a 4-inch cut-off disc on a die grinder with an extra backing he added to get a truer cut.

Notice how a horizontal cut...

Notice how a horizontal cut was made first, and then a vertical cut was directed from the rear and drawn towards the front.

This method allows a person...

This method allows a person more control of the cut-off wheel, hence a much straighter cut.

The Thunderbolt scoop was...

The Thunderbolt scoop was repositioned into place and marked to double-check where the last cut needed to be made.

This view shows the clearance...

This view shows the clearance between the sheetmetal and the front inner-support.

Once the piece was entirely...

Once the piece was entirely cut out, Matt was able to gain better access to remove more dents from the front of the hood.

He used a dolly on the inside...

He used a dolly on the inside to back the metal as he hammered from the front.

A few smacks later, and the...

A few smacks later, and the dents were flattening out.

A Unibody Auto-Spotter (Spitzenagel)...

A Unibody Auto-Spotter (Spitzenagel) was used to spot-weld copper nails to attach a slide hammer to help pull out the dents. Note that Matt applied a slight constant pulling pressure to the slide hammer as he tapped around it with a body hammer.

With the dents almost completely...

With the dents almost completely removed, the next step was to cut out a piece of sheetmetal to be used as a patch panel.

Matt used his homemade planishing...

Matt used his homemade planishing hammer to contour the nose of the patch-panel.

The patch-panel was test-fitted...

The patch-panel was test-fitted and it was determined more metal needed to be trimmed off.

Matt used a Rotary Shear to...

Matt used a Rotary Shear to trim the excess metal off. The Rotary Shear is more commonly found in a tin knocker's shop ("tin knocker" is slang for someone who does A/C and heating ducts) than an automotive body shop.

Tom and Matt rechecked the...

Tom and Matt rechecked the Thunderbolt scoop for fitment before the patch-panel was tacked into place. It was decided that the nose of the scoop would need to be brought down to conform to the hood. Since that's fiberglass work, we'll get to that next month.

Not warping the sheetmetal...

Not warping the sheetmetal is a major concern when it comes to welding the patch-panel into place. Matt dialed the heat way down on his 220/110 dual-voltage Miller welder to tack-weld the piece in.

The best way to ensure that...

The best way to ensure that the process was progressing in the right direction was to spot-weld a little and then grind and hammer the patch-panel to conform to the shape of the hood.

Matt added more weld in between...

Matt added more weld in between the spot welds to "stitch" the patch-panel in. Additional hammering was also done to keep the repair area flat.

Not rushing the job--by patiently...

Not rushing the job--by patiently adding welds and then carefully grinding--kept the patch-panel and the hood in perfect form.

Matt did a beautiful job of...

Matt did a beautiful job of metal-finishing the hood to accept the Thunderbolt hoodscoop. In next month's Custom Classic Trucks Tom Prewitt will take over and handle bonding the scoop on with SEM Products' special adhesives and then finish off the fiberglass work.