100 million engines and gear boxes manufactured – an impressive track record for Cléon

In the heart of the factory, huge pieces of machinery are powered up at the crack of dawn. Production lines are coordinated with such a high degree of precision, reminiscent of an orchestra. Operators assemble components to produce engines and gear boxes, overseeing every step of the process to ensure the quality and reliability of the finished product. From the meticulous design of the first engines, to the development of the most sophisticated engines and technology, Cléon has epitomised the pioneering spirit of a factory that has always redefined itself to fit the times.

The “Cléon fonte”, an iconic engine

Since its inauguration in 1958, the Renault Group’s Cléon factory has produced a wide range of engines, each carrying the hallmark of the factory’s ingenuity and expertise. The most famous such mechanical exploit remains the distinctive “Cléon fonte”, also known as the C-type engine, which continues to represent an important development, three decades after it was first presented at the Geneva Motor Show in 1962. It was fitted to a variety of Renault models, including the Floride, Alpine A110, Renault 5, Super 5, Renault 8, Renault 12, and Renault 18, as well as utility vehicles such as the Estafette and its replacement, the first generation Trafic.

The various technical adaptations made to this engine have turned the Cléon factory into a genuine technological laboratory. In 1981, the lower valve cover gasket and valve train, initially made from cork, started to be made from silicone, which then required new techniques to remove the seals. The layout also evolved for the Renault 9 and 11, from the initial longitudinal mounting and simultaneous assembly with the gear box and starter, the “Cléon fonte” engine moved to a transversal mounting, considerably reducing the noise inside the vehicle. This transition led to the replacement of the hydraulic timing chain tensioner with a mechanical tensioning device, thereby improving the engine’s performance and durability. The C-type engine was one of the first to adopt electronic ignition, the turbocharger and injection system. Its success can be quantified by its impressive production figures – over 14 million C-type engines were built at Cléon!

F-type and G-type engines, legends of the road

The F-type and G-type engines are two incredible feats of engineering that have blazed a trail on roads all around the world. The F7P engine, topped by a 16-valve alloy cylinder head, a double valve spring kit and two camshafts, was fitted to sportscars such as the Renault 19 16S, the Clio Williams and the Spider. The G-type engine was installed on top-of-the-range models such as the Laguna, Safrane, Vel Satis, Espace and Avantime. It introduced a number of groundbreaking innovations, including the two-piece connecting rod, cutting machining costs significantly. Moreover, the calibration of injection nozzles was revolutionised to meet the new environmental standards of the day. The G-type engine also pioneered the use of balance shafts, guaranteeing exceptional performance and unparalleled comfort.

Didier Van-Tornhout, who worked at the Cléon factory for nearly 40 years, spoke of how the team would constantly share and learn during this period.

Iconic gearboxes

The Cléon factory is renowned not only for its legendary engines, but also for its gearboxes that have powered many Renault models over the decades. The factory began producing gearboxes for the Dauphine and the 4CV, called the B2 and B3 gearboxes, in reference to the number of gears available. The 1980s saw the development of the J-type gearboxes, with ball or tapered rolling bearings. Over 21 million of these drivetrains were produced! Then, in 1991, Cléon started manufacturing P-type manual gearboxes, boasting five or six gears depending on the version. This piece is still manufactured today, and production has already reached 8 million units.

Innovative working practices and processes 

Over the decades, the Cléon factory has constantly sought to achieve excellence by reinventing its manufacturing practices. The first machining techniques were produced with single-purpose machines, specially designed for each part of the process. The factory then switched to simultaneous machining on a stationary piece of equipment to increase efficiency, while automation brought about transfer lines, creating a continuous production flow. The shift was then made to flexible lines, rigged with cutting-edge machining units, enabling the factory to save time when changing parts and guarantee quality.

Leading-edge technology

The Cléon factory has driven considerable technological progress. For example, thermochemical treatments have developed from a basic production line to sophisticated setups integrating panels and conveyors, thereby reducing assembly times. The introduction of robotics also revolutionised the production process. In the 1960s, failure alerts were signalled via a generic warning light, whereas nowadays, human/machine interfaces provide detailed descriptions of each fault. The integration of thermochemical treatments, in particular low pressure carburizing, improved the durability of components. Cléon has also modernised foundry work, moving from casting single parts with just low pressure circuits to products that integrate high pressure circuits, requiring specific expertise. The teeth of the pinions in the electric reduction gears of hybrid and electric vehicles were modified to reduce noise.

The challenges of electrification

To meet the needs of the modern world, the Cléon factory began focusing a long time ago on electrification, conducting the first studies on the ZOE motor. At that time, it was like heading into uncharted territory, and electric technology presented some serious challenges. First and foremost, it was necessary to learn to effectively produce electric motors, expertise that was then rare. Then, operators who specialised in internal combustion engines and conventional gearboxes needed to be trained and redeployed to work on electric vehicles. Despite these obstacles, the first electric motor came off Cléon’s production lines in April 2015 to power the ZOE, marking an important milestone.

“We learned that even though electric vehicles have fewer parts, the technology is highly complex and requires a high degree of precision. Our strength lies in the expertise accumulated over the decades producing engines and gearboxes, and it is this expertise that sets us apart. In 2017, we set up a division to focus specifically on the electric process. It started with just five people, but we have since sought out and brought in a wealth of talent, and our team is now made up of over 40 experts. Every day, we continue to learn, grow and push the boundaries on electric innovation,” said Patrice Duhaut, Process Expert Leader.

Over time, the factory has continued to evolve, producing the 5A engine for Renault and its partners and developing upgrades for models such as the Kangoo. This wound rotor synchronous motor, built without rare earths, was the first of its kind, epitomising the expertise of this iconic factory. The introduction of the 6A engine, fitted to the Megane E-Tech electric and the All-new Scenic E-Tech electric, represents a huge leap forward with its design that boasts 30% more power in a motor 30% more compact.

To step up the pace of this transformation and remain at the cutting-edge of technological progress, Cléon opened an electric university. Over 3,000 people are currently employed in the Cléon workshops, contributing to the success of this radical transformation.