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.
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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 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. |