Lotus 21 inboard suspension

There are certain elements of modern Formula 1 car design that are universal and barely warrant a second glance; one example being the use of inboard suspension. This is where the spring and damper unit (in the case of a current car a torsion bar mounted longitudinally in the chassis with a separate damper) is mounted inboard from the suspension arms, normally actuated by a rocker.

This was not always the favoured set-up. Through the 1950s and into the early 60s, most F1 cars featured double wishbone front suspension with the coil over spring/damper mounted to the lower wishbone and a locating point on the chassis.

While there is nothing inherently wrong with this setup, (in fact there are many sports cars today that still utilise it, such as the Ginetta G55 GT4), there are downsides in an open wheel, single seat application. In 1960, Colin Chapman, originator of so many innovations, recognised this and set the tone for the next half century of suspension design.

The Lotus 21, released for the 1961 season and replacing the successful 18, was designed specifically for the new 1 ½ litre rules. It was supposed to run the newly designed Coventry Climax V8, but with development of this engine delayed it was rejigged to accept Coventry’s FPF 4-cylinder.

A noteworthy feature of this diminutive and sleek car was the front suspension. Rather than sticking with the conventional layout described above, and employed on the 18, Chapman opted to use a fabricated upper wishbone, pivoting on the upper chassis rail. But the shock didn’t pass through the wishbone and was instead mounted inboard of the chassis rail, actuated by an extension of the wishbone arm, effectively forming a rocker.