Le Mans still has the reputation of being the most punishing endurance race in the world. With its association with powerful engines in combination with perfectionism and professionalism, a victory in the world’s most famous endurance race represents a unique opportunity to bolster one’s image and benefit economically for both racing teams and manufacturers. Many manufacturers were already putting their trust in innovative ZF technology back then.
The racing success of the Lotus in the early 60s spurred manufacturers and racing teams to seek the assistance of the drive specialist based near Lake Constance: While attention was initially focused on the smaller 5 DS 12 and 5 DS 20 versions, it quickly became clear that a larger version was necessary in the area of long-distance racing as well as in volume production of sports cars. The fact that the heavier-duty transmission version 5 DS 25 was primarily in use at the traditional Le Mans 24-hour race – the emotionally charged zenith of endurance motorsports – was for the following reason in particular, which is also explained in the current blockbuster Ford v Ferrari, aka Le Mans ’66:
Henry Ford II decided to go to war with Ferrari, which maintained a Le Mans winning streak from 1960 to 1965 – and a replacement had to be found for the Colotti transmissions previously installed by Ford. After Ford ventured to Le Mans for the first time with the GT 40 in 1964, shortly after the first test runs with this race car in April, several of the 4.2-liter vehicles had to abandon the race due to transmission failure despite having set a new lap record and top-speed benchmark. Ford then awarded ZF the contract to develop a reinforced racing transmission that could withstand the 24-hour race, resulting in the next performance stage for the series, with an integrated differential and featuring 250 newton meters of torque: the 5 DS 25. However, this racing transmission was also able to transmit more power.