How the Renault 4F Helped Revolutionise Formula 1

Versatile and tough, the Renault 4F helped countless businesses to grow. What you may not realise, however, is that this unassuming estate derived from the 4L also played a part in transforming Formula 1.

In the mid-1970s - specifically in 1977 - Lotus, having already secured back-to-back Constructors’ titles in 1972 and 1973, was beginning to lose ground to its rivals.

Looking for an edge, the brilliant founder of the British marque, Colin Chapman, chose to pursue a new idea (and a “loophole” in the regulations) which, at least on paper, could change motorsport: ground effect.

From theory to reality

Put simply, engineers worked out that by fully covering/sealing the sides of the single-seater with a “skirt”, they could generate the desired ground effect and effectively “stick” the car to the track.

After successful wind-tunnel work and multiple simulations, there was little doubt the concept could take Lotus back towards its glory days. Even so, the engineering team still had one key question: how could they be sure ground effect would actually work on track?

It is one thing to test scale models in a wind tunnel and run simulations; it is quite another to apply the same concept to a Formula 1 car and send it out onto the circuit.

To make matters harder, the team at Hethel did not have spare single-seaters available for testing, nor did they have the modern simulators and computing power teams rely on today.

So they had to follow, to the letter, a maxim Guilherme Costa often reminds us of here at Razão Automóvel: Improvise. Adapt. Overcome. That is how the Renault 4F entered the story.

Renault 4F: the all-round workhorse

Once at the Lotus factory, the Formula 1 engineers had an idea: what if we fixed one of the “side skirts” to a frame attached to the rear of a Renault 4F to see how it behaves?

With the van’s rear door open, one engineer lay in the load bay watching how the test solutions behaved, while another drove the Renault 4F as the testing programme progressed.

Interestingly, the French estate’s soft suspension - designed more for rough tracks than racing circuits - turned out to be an unexpected advantage, amplifying the movements the “skirts” would experience once fitted to a Formula 1 car.

This approach made it possible to discard less suitable options until they arrived at the best one: a flap with a spring made from a low-friction material, similar to what is used for the… chopping boards we have in the kitchen.

The solution was introduced on the Lotus 78, but it was on the Lotus 79, in 1978, that the system truly shone. Thanks to it, Lotus became the “team to beat”, won five races in the second half of the season, secured the Constructors’ title, and watched Mario Andretti take the Drivers’ championship.

In 1979, several other teams had already copied and refined the system, wiping out Lotus’s advantage. Even so, none of them can likely “boast” of having used a Renault 4F as a “test car”.

---