If there’s one subject that gets washed over when transplants or modifications are discussed it’s the flywheel the movie and clutch assembly. There also seems to be a widely held belief that up-rating an engine from anything other than standard automatically requires a competition clutch.

Although many people have written much about how to modify engines, very little has been written about the flywheel and clutch.

In the very early years, the Mini was endowed with a spring-operated clutch, adapted from in-line engine duty to suit the peculiar new gearbox under engine configuration. Various modifications were tried on subsequent production cars, including the first 1071cc Ss. By 1964 however, The BL design team concluded something else was needed.

Enter the two-piece flywheel, then in about 1973 a one-piece version, both using a diaphragm mounted disc-spring type. The disc-spring type lent itself to easy modification, both in weight and spring pressure. The development of the venerable A-series engine in all guises saw power outputs climbing relentlessly, so higher spring pressures were needed to harness it to avoid the dreaded clutch slip and consequent destruction of clutch plates. The two-piece flywheel had a steel centre-piece that bolted to a cast outer section. The one-piece cast flywheel became standard fitment across the range more for production reasons.

The only A-series transverse engine that had a different flywheel was the Austin 1300 type. An extra cast-on ring of something like an inch by three-eighths of an inch was added, supposedly to improve idle and high-speed smoothness. It weighed a ton so was undesirable for competition use.

The advent of Japanese cars with extremely light pedal operation instigated the change to the Verto clutch and Flexplates assemblies. The old diaphragm type with its variety of spring rates available was man enough for any job, but did make the clutch very heavy to operate by comparison to these new-age cars.