IMSA 1969-1989: The AAGT concept comes of age

Image by Tony Mezzacca /Bob Brandle

IMSA 1969-1989: The AAGT concept comes of age


IMSA 1969-1989: The AAGT concept comes of age


As we build up to this year’s Rolex 24 at Daytona, is pleased to bring you a series of excerpts from IMSA 1969-1989 by Mitch Bishop and Mark Raffauf. The soon-to-be-released inside history of IMSA’s first two decades is currently available for pre-order from Octane Press, and as a reader, you can get $10 off by applying the discount code RACER19 at checkout. Click here for ordering information,  and look for the next excerpt on Tuesday.

The Camel GT Series was on a roll by 1976. Average race attendance topped twenty-five thousand people, guaranteed race purses exceeded $31,000, and the fields had now become more diversified with AAGT machinery fighting on equal terms with factory-produced Porsches and BMWs. The series was attracting global attention due to the participation of top-flight sports car talent from Europe, including Brian Redman, John Fitzpatrick, Hans Stuck, Ronnie Peterson, and others. IMSA was making money; by midyear, John and Peg were able to pay off all the original NASCAR loans needed to start the business.

The AAGT concept gained speed with Porsche’s focus on the 934 and the Trans-Am for 1976. It put the top IMSA Porsche teams in a bind. Could they be competitive with the now-aging Carrera RSR against the BMW CSLs and new AAGT Monzas?

Holbert decided the answer was no. Although he had lobbied for the inclusion of the Porsche 934 for 1976, he preferred the larger rear wing, wider rear tires, and lighter weight of the Monza compared to the RSR. Holbert purchased a DeKon Monza for the 1976 season and ran his first race with it at Road Atlanta in April after wisely sticking with the more reliable Porsche RSR for the longer Daytona and Sebring rounds. He finished second at the 24 hours of Daytona and won Sebring in March, co-driving with Michael Keyser, who then also switched to the Monza.

By the Road Atlanta round in April, eight small-block Monzas showed up from three constructors, including examples fielded by Keyser, Agor, Trueman, Nehl, Tom Frank, and Jerry Jolly. There were many other AAGT cars as well: Coleman’s original AAGT Vega, five Greenwood-style Corvettes, Charlie Kemp’s wild Cobra II built by Bob Riley, and a host of Camaros led by the big orange No. 21 of Carl Shafer. Holbert and Keyser finished first and second in their DeKon Monzas, humiliating the rest of the field. The AAGT era had officially come of age.

Holbert went on to win four more races in the Monza to take the 1976 Camel GT championship, his first in IMSA competition. Keyser won two races with his version as well, cementing the future of American-built, tube-frame racers as the equal of anything produced on assembly lines in Europe. The Porsche Carrera RSR contingent included the usual faces along with George Dyer, Roberto Quintanilla, Bob Hagestad, John Gunn, John Graves, Monte Shelton, and others.

Carl Shafer’s AAGT Camaro leads Jim Busby at Mid-Ohio. Busby was hired by Peter Gregg to drive the Brumos Carrera RSR in 1976 after Gregg switched to the BMW CSL for one season. Busby was a former drag racer who burst onto the IMSA scene that year, winning four races. Image by

The AAGT revolution continued unabated for several years. Holbert won a second championship in an upgraded Monza in 1977 against an onslaught of Porsche 934/5s and the debut season of the Porsche 935. Other manufacturers became involved in the AAGT class, including Bob Sharp with the Datsun 280ZX twin turbo V8. The bodywork, aero packages, and engines got so outrageous that IMSA dropped the AAGT moniker and changed the name of the class to GT eXperimental (GTX) in 1978. GTX became a combined class that included Group 5 Porsche 935s and all manner of AAGT machinery.

For the 1976 season, Gregg switched to the BMW CSL, which continued to receive factory support but was vastly outnumbered by the mobs of Porsches and AAGT machines that entered every event. Despite this, Gregg won two races (the 24 Hours of Daytona and Talladega) and finished in the top ten enough times to challenge for the season championship, finishing second in the points.

For most of the season, Gregg hedged his bets by paying Jim Busby to race a Carrera RSR in Brumos colors, carrying the number 61. Busby became a regular on the circuit and was the sensation of the year, dominating the 500-mile event at Mid-Ohio in August, driving solo the entire distance, and winning sprint races at Sears Point, Laguna Seca, and Ontario, where he barely edged his boss in the BMW by punting him off the track on the last lap. Later that year at Lime Rock, Gregg presented his bashed-in BMW door to Busby as an ironic trophy to hang on his wall. As part of his contract with Brumos, Busby was paid a $5,000 bonus for every race win, which usually came at the expense of his boss, Peter Gregg. The fact that Gregg had to sign each of these checks personally had to be especially galling for the IMSA champion.

Dyer, in his Carrera RSR, won for the first time in his Camel GT career at the traditional Memorial Day Lime Rock round by one thousandth of a second when Michael Keyser had a costly miscommunication with his crew, which had radioed him that the race was over when, in fact, it had one lap to go. The close finishes continued at Mid-Ohio where DeKon Monza drivers Keyser and Holbert were separated at the finish by one-tenth of a second. Starting with Busby’s win at Ontario, three consecutive Camel GT races were decided by a total of less than two and a half seconds.

IMSA sanctioned a Formula Atlantic series for just one year in 1976. Gilles Villeneuve, with his classic oversteer style, won the title against the likes of Bobby Rahal, Price Cobb, and Elliott Forbes-Robinson. Image by

The year also marked the first and only time IMSA sanctioned a Formula Atlantic series. The six-race schedule dovetailed with the similar Canadian series and featured Gilles Villeneuve, who won the title over Price Cobb, Elliott Forbes-Robinson, and Bobby Rahal, among others. All would go on to bigger things. Villeneuve famously drove for the Ferrari Formula One team. Cobb would co-drive to victory in the Le Mans 24-hour in addition to numerous Camel GTP prototype wins. EFR won a Trans-Am title and twice co- drove to overall victories in the 24 Hours of Daytona. Rahal went on to win three CART championships, the Indy 500, the 24 Hours of Daytona, and the Sebring 12 Hours.

Throughout the fall of 1976, strong lobbying by Porsche and its customers began to create a revised IMSA philosophy for the following year. AAGT Monzas were more than capable of keeping up with existing Porsches and BMWs. The growth of FIA Group 5 in Europe with Porsche 935s, BMWs, and the Ford Capri was paving the way for a future of silhouette GT cars. The result was a complete rethinking of the Camel GT rule book that allowed turbos, larger tires and rear wings, front splitters, and more liberal bodywork regulations.