Firebird Convertibles prior to 1991.
It is well known that Pontiac did not officially offer a convertible Firebird during the 1970–1990 model years. Beginning in 1987, Chevrolet offered the Camaro as a convertible, yet the Firebird remained unavailable in that configuration. Over the years, many theories have circulated as to why Pontiac chose not to follow suit. The true reason is likely lost to history—and if it ever existed in writing, it has probably never been publicly disclosed.
My belief is that Pontiac wanted a convertible but was unable to offer one at the time. Two common explanations are often cited:
that the ASC conversion process did not meet Pontiac’s quality standards, and
that Pontiac believed there was insufficient market demand.
I do not believe either explanation is correct.
What follows is somewhat lengthy, and parts of it may not seem directly related to convertibles at first glance. However, taken as a whole, the reasoning behind my conclusion becomes clear.
When the LB9 (305 TPI) engine was introduced in 1985, the upcoming 1986 emissions standards had not yet taken effect. The 1985 LB9 with an automatic transmission was arguably one of the most impressive engine introductions since the early 1970s, offering roughly 20% more power than the carbureted 305 while also delivering improved fuel economy.
In 1986, the L69 engine was dropped from both Pontiac and Chevrolet F-body cars. While it appears the engine continued to be offered in G-body applications, it was removed from the F-car lineup due to vapor lock issues—why this problem affected the F-body but not the G-body remains unclear. Only 26 L69 Trans Ams were produced, most of which were sent to Canada for the Players Challenge series.
Although the LB9 was more efficient overall, it struggled to meet 1986 emissions requirements. As a result, it was significantly detuned for both emissions compliance and fuel economy. This included a milder camshaft and an upgrade from an 8-bit ECM to a 16-bit system, allowing greater processing capability and improved efficiency.
Beginning in the 1970s, the EPA implemented Corporate Average Fuel Economy (CAFE) standards to regulate vehicle efficiency across manufacturers’ fleets. While individual vehicles carried city and highway MPG ratings, compliance was based on the manufacturer’s overall average.
By 1987, Pontiac was walking a very fine line.
That year, the LB9 became available with the M5 Borg-Warner manual transmission, and the L98 (350) engine was introduced—automatic only. During development of the 1987 GTA, fuel economy was a major concern. Many features available on Firebirds and Formulas were not available (NA) on Trans Am or GTA models equipped with the 350. For example, subwoofer controls and rear window shades were unavailable on U.S.-market 350 GTAs but were offered in Canada.
Pontiac was clearly attempting to improve overall efficiency and avoid triggering a Gas Guzzler Tax.
It is also notable that from 1987–1988, Firebirds were officially unavailable with both T-tops and the 350 engine. While some cars exist with this combination, most were either C&C conversions or cars that slipped through production unintentionally. Chevrolet, by contrast, appears to have produced a greater number of Camaro T-top 350 cars during the same period.
In 1989, T-tops with the 350 finally became widely available. That year marked a dramatic shift in production:
6,478 LB9 (305) engines
13,041 L98 (350) engines
For the only time, L98 production more than doubled LB9 output. This followed 1988, where production was nearly equal (10,383 LB9 vs. 10,798 L98), and 87 (16,346 LB9 vs 11,384 L98)
Given Pontiac’s concerns about weight and fuel efficiency, a convertible Firebird would have been problematic. Convertibles are heavier and less aerodynamic, resulting in a higher coefficient of drag. Introducing a convertible—especially a Trans Am—would have further hurt CAFE numbers.
Offering only a base Firebird convertible while excluding the Trans Am would likely have confused customers and diluted the brand. Ultimately, Pontiac waited until 1991 to officially offer a convertible, coinciding with a more mature LB9, improved aerodynamics, lighter F-body revisions, and the removal of some GTA luxury features such as steering-wheel controls and formed door panels.
By 1986, both Chevrolet and Pontiac were well aware that third-party companies were converting T-top Camaros and Firebirds into convertibles. Companies such as Matrix3, Hi-Line Customs, and Autoform produced approximately 2,000 conversions combined, often at a cost of around $4,000 per car.
American Specialty Cars (ASC)—formerly American Sunroof Company—produced what was widely considered the best conversion. Their designs used stamped metal tonneau covers and trunk lids, resulting in a clean, factory-like appearance whether the top was up or down.
ASC also had extensive experience with GM vehicles, contributing to or producing convertibles for numerous models, including the Corvette, Riviera, Eldorado, Reatta, Sunbird and Cavalier.
In 1987, GM selected ASC to produce F-body convertibles. Chevrolet received an official Camaro convertible, while Firebirds—being mechanically similar—were converted for dealership sale. Because Firebird convertible production remained low, ASC was not required to submit EPA fuel-economy data (500 units being the general threshold).
Interestingly, early owners report that all convertible-related service from 1987–1990 was performed by Pontiac dealerships, using GM-part-number components, as though the cars were factory-authorized.
ASC produced the following Firebird convertibles:
1987: 173
1988: 104
1989 (330 total):
36 – LB8 Firebird
56 – LO3 Firebird or Formula
18 – LB9 Formula
43 – L98 Formula
4 – LO3 Trans Am
9 – LB9 Trans Am or GTA
158 – L98 Trans Am or GTA
2 – LC0 Turbo Trans Am
4 – Unlisted / Unknown
1990: None
1991: 989 Base Firebird & 637 Trans Am
1992: 1315 Base Firebird & 777 Trans Am
Although 1986–1989 Firebird convertibles were not official GM production models, buyers should keep several points in mind:
Structurally, ASC Firebird convertibles are essentially identical to Camaro convertibles of the same years. Parts are readily available. Differences are limited to cosmetic items such as quarter-panel spears, spoiler, and third brake light.
Specialty dealer cars from the past (e.g., Yenko, Berger) were also not factory-authorized yet remain highly collectible today. Lack of “official” status does not equal lack of value.
From 1987–1992, no F-body convertibles were built by GM. All were ASC conversions. The only difference between “official” and “unofficial” cars is a single VIN digit—structurally, they are the same.
In short, I believe Pontiac’s decision not to offer a Firebird convertible prior to 1991 came down to fuel efficiency, not quality, demand, or structural limitations. The same logic explains why no production Camaro or Firebird convertible was offered with a 350 during that period—it was an EPA and CAFE issue, not a torque or chassis issue.
—
okfoz
Webmaster,
3rdgneformula.com