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70 years Lotus 70 years Lotus

Among Friends – Part 2

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ZF and Lotus enjoyed an extremely successful and intensive partnership in the 1960s. Charismatic innovator Colin Chapman was a frequent visitor to Friedrichshafen to coordinate his driveline concept with engineers...
Janine Vogler,
Janine Vogler Vintage cars related to ZF-products have been at the heart of the journalist. Outside of work, she enjoys to ride motor bike or to be accompanied in nature by her dog.
The cooperation between ZF and Lotus was extremely profitable for both sides - the winning titles clinched in the 1960s comprise a huge listing. Racing drivers such as Jim Clark and Graham Hill became icons and continue as racing history icons to this day.

Jim Clark alone competed 72 times for Lotus in Formula 1, while Graham Hill became Formula 1 World Champion again in 1968 on a Lotus Type 49, equipped with the 5 DS12 transmission from ZF. With this race car type and ZF technology, drivers won twelve times in world championship races. In addition, Lotus was able to win the Constructors' World Championship in Formula 1 three times during the years with ZF. As a result, Colin Chapman and the Lotus team often paid a visit to Friedrichshafen on their way to Monza.

The DS transmissions have been continuously developed in consultation with Colin Chapman: The 5 DS10 was expanded as the 5 DS12 (120 Nm) and most recently as the 5 DS20. Jim Clark won the legendary Indianapolis 500-mile race in 1965 with the Type 38 and a ZF 5 DS 20, in which the Newton meter figure had already been increased to 200. Jim Clark and Colin Chapman, in gentlemanly fashion, immediately thanked ZF by telegram afterwards, both congratulating ZF on the victory and expressing their enthusiasm for the constructors' achievement. A great gesture, which on the one hand certainly paid tribute to the high engineering skills of the ZF technicians - but on the other hand also reflected the congenial, charming manner of the congratulators and their close, trusting relationship with the designers at Lake Constance.

Although the connection between ZF and Lotus was very much one of partnership, in business terms it lasted only until the end of the 1960s. The tragic events of 1968 with the loss of Jim Clark and Mike Spence certainly shocked ZF employees and in some way slowed down the previously highly praised commitment of the engineers.

Because the helpful commitment from Lake Constance proved to be very time-consuming and cost-intensive in the small quantities involved, only a very small number of transmissions and parts were produced, which the Lotus team had used successfully over the years. It is reported, for example, that Colin Chapman had repeatedly not only strongly praised the ZF transmissions and their reliability and longevity - but he had even noted that no other transmission could be found in all his tests that came close to the reliability of the ZF units. However, he had concerns about supplies in 1963. Accordingly, the 5 DS10 was already running in its third season and the first signs of wear were appearing. In some cases, the aluminum housing no longer played along and began to expand due to the high load. ZF engineers then strengthened it again and again by adding gray cast iron parts to the sides. Jim Clark himself pointed out that even in this generation, speeds of 9,700 rpm were transmitted, but the transmission was only designed for 7,500 rpm.

Overview of Lotus gearboxes in use
Typ 25 F1 1962-65 ZF 5DS10
Typ 30 Sports 1964-65 ZF 5DS12
Typ 32B Tasman 1965 ZF 5DS20
Typ 33 F1 1964-66 ZF 5DS10
Typ 34 Indy 1964 ZF 5DS20
Typ 38 Indy 1965 ZF 5DS20
Typ 42 Indy 1967 ZF 5DS20
Typ 48 F2 1967-68 ZF 5DS12
Typ 49 F1 1967 ZF 5DS12
Typ 58 F2 1968 ZF 5DS12
Typ 62 Sports 1969 ZF 5DS12
Typ 63 F1 (four wheel drive) 1969 ZF transfer
Typ 64 F1 (four wheel drive) 1969 ZF transfer

A later reproduction of the first variants was no longer economically feasible, so Colin Chapman began looking for alternatives, especially since he could no longer claim exclusive rights for the subsequent 5 DS12 and 5 DS20 transmission generations. These drive types were also sold to BMW, Ford and Cooper-Maserati. Here too the number of units was extremely manageable: about 60 units of the 5 DS20 were delivered. At Lotus, it was used in the Type 30, Type 32 B (Tasman Car) and the Indianapolis cars Type 34, 38 and Type 42. After 1969, only individual transmission components were delivered to Lotus, such as drive gears and disc bevel gears.

The Lotus team needed fast and flexible solutions in that individual components could be replaced at short notice to be able to tune the transmissions to the respective track. However, this was not feasible with the ZF units: as reliable and precise as they were, they were also as complicated and sophisticated in their internal arrangement and design. It is true that after the world championship success of 1963, the next version 5 DS12 had the first gear reinforced and the oil lubrication improved, and the differential and output shaft were also enlarged. In addition, the shift gate was placed inside the housing, which made it much easier to adjust the shift linkage. In return, this type of transmission was also used in the Lotus Type 48 and Type 58 Formula 2 cars and in the Type 62 sports racing version. Nevertheless, changing gear ratios at short notice was not feasible, so the team still had to bring at least two spare gearboxes for each car: one with a higher and one with a lower axle reduction.

Chapman's son Clive, who today with his Classic Team Lotus looks after the Formula 1 Lotus legends still used in historic racing and restores the legendary monocoques, recalls:

"My father had always stressed that there had been a close, strong connection between Lotus and ZF. The ZF designers and the Lotus designers had the same, precise way of working and because of that they were on the same page. It was a productive work and relationship that meant a lot to my father and that he considered very valuable. It would be nice if that connection could be carried forward into the future..."
Clive Chapman - Classic Team Lotus

After winning Indianapolis in 1965, Jim Clark thanks ZF employees with this greeting card.

On the way to Monza, the Lotus team stopped by ZF in Friedrichshafen several times.

Courteous treatment: In the letter, Colin Chapman thanks the then ZF Board of Management member Dr. Maier.

A point of honor: The Lotus team loading a racing car in Friedrichshafen in 1963.

With the Lotus Type 38, Jim Clark won the legendary 500 miles of Indianapolis, the largest race event in the USA, in 1965. The original car stands at the Henry Ford Museum in Dearborn.

Finnish F1 racer Heikki Kovalainen was a new starter for the now Malaysian racing team Lotus Racing in 2010. Here he has a historic Lotus Formula 1 car explained to him at the Classic Team Lotus Festival.

Heikki Kovalainen and his teammate Jarno Trulli at the biggest historic Lotus event - the Classic Team Lotus Festival in 2010.

Beautiful icon: The Lotus Type 38 Jim Clark's car, with which he won the legendary Indianapolis 500 miles in 1965.

Clive Chapman is happy to see that there are still a few Lotus running with their original ZF gearbox.