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Garretson’s 935

Posted by on Nov 6, 2017

Garretson’s 935

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This is a special story about a very special Porsche 935 that was raced for more than 70,000 miles. The story actually starts a little earlier, but is mostly about this remarkable 935 that not only raced as a 935, but also masqueraded as a 934 and as a 930S, whatever was necessary to make this remarkable car eligible for the various racing classes in IMSA. Our story actually begins before this car was built and includes a little of the history of Porsches turbocharged 911s and some of the various different racing cars derived from those turbocharged 911s.

A prototype 911 Turbo was first shown at the Frankfurt Auto Show in September 1973 to test the market potential of such a car. The production version of this car was introduced at the 1974 Paris Auto Show and then put into production as the type 930 Turbo Carrera in 1975. The original purpose of the Turbo Carrera was to gain homologation for the Group 4 and Group 5 cars that Porsche originally intended to race in the Manufactures Championship from 1975 on. To qualify as a Group 4 Grand Touring car a quantity of at least 400 units had to be produced over a period of 24 consecutive months. The original plan was to build the necessary 400 required for homologation and then cease production, but the car became such a success that it remained in production for fifteen years and in those fifteen model years between 1975 and 1989 over 20,640 the original 911 Turbos were built.

The change to Groups 4 and 5 classes was delayed by FIA (Fédération International de l’Automobile) from 1975 for one year until 1976. In 1976 when the rules for the World Championship of Makes were finally changed by the F.I.A. Porsche produced two new 911 based racing cars for the resulting Group 4 and Group 5 classes, the 934 and 935. The 934 was homologated as a Group 4 car and sold to Porsche’s racing customers for GT (Grand Touring) racing, while the 935 was a Group 5 car and only the factory planned to race them. Although the Group 4 rules were really quite strict and restricted the 934s to very nearly to the same production configuration as the 930s the Group 5 rules were a much more liberal. The Group 5 class was based upon silhouette formula where the cars were offered a great deal of latitude as long as they resembled the basic silhouette of the car from which they were homologated. The rules stated that the aerodynamic devices not homologated for series production must fit with the cars frontal projection. What they mean by this is that when you view the car from the front the rear spoiler cannot stick out into view from the silhouette of the car, and this is in essence what they meant by the silhouette formula.

Thirty one of the group 4 934s were produced for Porsche’s racing customers in 1976 and 1977. Most of these cars remained in Europe and competed in the Group 4 category. Toine Hezemans won the 1976 European GT with a 934. Only two of the 935s were built by Porsche for use by the Martini sponsored Porsche factory race team. The Martini team won the 1976 World Championship of Makes with these two 935s

In the U.S. I.M.S.A. (International Motor Sports Association) had said no to the Porsche Turbos preferring to try to encourage Porsche to continue to build and support the normally aspirated RSRs in their series. Porsche, being a small company could not support more than one racing series at a time with customer racing cars and they had already chosen the Group 4 934 so there would be no more RSRs. SCCA (Sports Car Club of America) welcomed the Group 4 934s with open arms. Vasek Polakbought five and Al Holbert one to race in the popular SCCA Trans-Am series. Several different drivers drove the Polak cars over the year, but George Follmer drove for Vasek most of the season and was rewarded for his efforts with the 1976 SCCA Trans-Am championship. Al Holbert spent most of his time with his Chevrolet Monza winning the I.M.S.A. championship and had little time to race his 934 in the Trans-Am series.

For 1977 I.M.S.A. not only relented and let Porsche’s customers race turbocharged Porsches, they also relaxed the rules letting an even more potent cross between 934 and 935 called the 934/5 or 934 1/2 compete in their series. Porsche produced a special series of ten special I.M.S.A. legal 934s which took full advantage of the more liberal I.M.S.A. rules and used many of the mechanicals from the 935. The I.M.S.A. cars were able to run with a lighter weight, wider fifteen inch wheels, tires and fenders, larger group 5 rear aerodynamic wing and the Bosch plunger- type mechanical injection instead of the CIS system. This change was to make the cars faster, more pleasant to drive, more reliable and able to produce nearer the 600 horsepower of the 935 instead of the 500 horsepower of the Group 4 version.

In Europe, over the 1976 season, a number of Porsche’s racing customers had been converting their Group 4 934 racers to Group 5 specifications, so for 1977 Porsche also produced a small series of thirteen cars (Type 935/77) for their customers to race in Group 5 with. The new cars were a customer version which were in effect replicas of the two original 1976 factory single turbo 935s (Type 935/76).

For the 1977 season the factory team had a new 1977 version of the 935 for their own use. The factory 935/77 was quite different from the customers version and had new body work which had running boards, a new front end that had fared in mirrors at the edge of the fender which also served as fences to keep the air from spilling off the front end improving the downforce on the front end. They also had a raised false roof section to clean up the airflow over the back of the car making the rear wing more effective. The running boards were used to improve the air management and were the beginning of efforts to provide some ground effects for the 935. The rules said that the car had to retain its original rear window in its original location, but it did not say that there couldn’t be a second rear window over the original so that’s what they did. This new false roof faired into a new rear wing, and they used the edges of this false rear roof section as air inlets for the engine. This car again won the world championship of Makes for Porsche with the help of several of the customer teams racing the customer version of the Porsche 935.

I.M.S.A. decided to let people update their 934s to 935 specifications and also to let the 935s race in their series in 1978. Our story starts with the very last 935/77 built. Californian, Dick Barbour added the car to his team at the beginning of the 1978 season where it was a solo entry by the team at the first race of the season, the Daytona 24 hour race in Florida, in early February 1978. It was a good start for the team, Barbour, Manfred Schurti and Johnny Rutherford drove the teams 935/77 to second place to the German GELO team’s 935/78 that was entered by Brumos Porsche and Driven by Rolf Stommelen, Tony Hezemans and for a one hour stint by Peter Greg. The next race for Barbour’s 935/77 was Sebring where the car qualified second but did not finish. However, another Barbour team 935 driven by Brian Redman, Charles Mendez and Bob Garretson won Sebring so the Barbour team was improving on their good start. Barbour drove again with Johnny Rutherford at Talladega Alabama where they placed third. Barbour drove his 935/77 solo to a sixth place finish at the May Laguna Seca race in Northern California, which was the fourth time, and turned out to be the last time, he was to drive this 935/77.

From 1978 on Porsche left the defense of the World Championship of Makes, which was based on these Group 5 cars to their customers. For the both the 1978 and 1979 seasons the Porsche customers did bring home the World Manufactures’ Championship for the Porsche factory. To encourage the private teams to compete in the manufactures championship Porsche created what they called the “Porsche Team Cup” to be awarded to the private Porsche customer team accumulating the most points in races counting towards the World Manufactures Championship.

The Martini sponsored factory team only raced one 935 in 1978 “Moby Dick”.The “Moby Dick”car was built with an aluminum roll cage/tube frame, the center section of the car was lowered and the floor section was raised up to regain the ground clearance. All new body work was developed to take advantage of the car’s lower profile for improved aerodynamics. “Moby Dick” was created with the intention of doing well in just one race, Le Mans. At Le Mans the emphasis is more on straight away speeds rather than cornering speeds so the cars aerodynamics were compromised towards high speed rather than downforce. “Moby Dick” only raced four times and only won at Silverstone, but the concepts it established had a great influence on the future of Group 5 racing and Group 5 racing cars. Some of the features of this car were larger brakes, improved aerodynamics and its upside down transmission. The upside down transmission was utilized to reduce the severe angle of the rear drive axles created by lowering the car as much as they had with the larger diameter 19 inch wheels and tires.

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