Ford started with a ‘Mk8’ Fiesta some 71mm longer than the ‘Mk7’, whose front track width had already grown by 30mm compared with that of its predecessor. But the Ford Performance in-house tuning team went wider again on that driven axle, ending up with a whopping 48mm increase on track compared with that of the old Fiesta ST.
Attached to that front axle are several key developments for the car. One of them is the most direct steering rack to be fitted to a front-driven Ford. At 12:1, its gearing is 14% quicker than that of the old ST, though it’s a fixed-ratio system.
Another is a limited-slip differential – the first to be offered on any Fiesta hot hatchback. It is a helical unit supplied by Quaife that works across the front wheels in tandem with a brake-actuated electronic torque vectoring system. The LSD isn’t standard but rather comes as part of Ford’s £850 ST Performance Pack.
The ST adopts derivative-specific front wheel hubs at the bottom of MacPherson-style strut front suspension, with torsion beam suspension at the rear. Damping is via Tenneco RC1 frequency-selective shocks which, though they’re not ‘adaptive’, are effectively double-valved and can switch between softer and firmer settings depending on the profile of the bump being dealt with. This contributes to what Ford’s chassis engineers describe as a more supple quality to the new ST’s ride than that of the last version.
The Fiesta ST also uses ‘force vectoring’ directionally wound suspension springs at the rear axle, which apply a stabilising lateral force on the wheels as well as cradling the car’s mass, and allegedly sharpen handling response. The springs are a Ford patent; they permit the use of softer rear suspension bushing than would otherwise have to be used (which should also improve ride), and they make for a rear axle 10kg lighter than if Ford had adopted a Watt’s linkage to achieve the same result.
Finally, to the engine: Ford’s all-new, all-aluminium, 1497cc three-cylinder turbo petrol, which produces official peak outputs of 197bhp at 6000rpm and 214lb ft, and transient ‘overboosted’ torque of 236lb ft. Those match the equivalents of the ultimate version of the last Fiesta ST (the ST200) precisely, although they’re not quite class-leading figures.
One of the advantages of the new engine, says Ford, is that it makes a broader band of peak torque than the old four-pot, that it’s lighter too, but also that it’s the world’s first three-pot automotive engine that can switch onto two-cylinder running under low load conditions.