GRR Garage: The genius of the Fiesta ST’s suspension

You will appreciate that the spring cushions impacts from the road surface. But a spring alone would allow the car's mass to keep bouncing as the impact attenuates. The damper compresses in sympathy with the spring, but then acts against it, stopping the car from kangarooing down the road after hitting a bump. All basic stuff.

Of course, when in boy racer mode, the impacts are many and varied. First there are the holes in the road, some of which are vicious. Then there are the lumps and undulations, which can send a car off-line. And finally, there's body roll when cornering. In each case the frequency – or ferocity – of impact is different. 

This is where the Fiesta ST’s Tenneco trick dual-valving (on the front) and RC1 valve (at the rear) technology comes in, allowing the damper to tackle different frequencies – or varying intensities of impact - simultaneously. In other words, the damper contains the cornering roll and mild undulations (longer impacts, less acceleration) while the additional valve is tuned to contain severe undulations and impacts from large, foxtrot oscar potholes (shorter, faster, more vicious impacts).  

This is why, over some of the war-torn roads around Goodwood, the Fiesta ST comes into its own and you can feel the effect of the springs and dampers on the way the car handles. Without such effective dampers, once loaded with cornering force, lesser dampers would not be able to control the impact from the deformations. In a lesser car, for a millisecond the pressure on the tyre’s contact patch would be reduced, allowing it to slip sideways under the cornering force. In the ST you feel just a slight movement but no loss of grip. It's the way the dual-valve dampers work on that kind of country road that mark this lil’ blue beast above its competition at speed. The same technology provides a more supple ride in town and at lower speeds, making it a more-than-bearable daily driver.

Ford claim much from their patented ‘force vectoring springs’: perhaps to emphasise how they combat lateral compliance and toe-out movement inherent with twist-beam suspension set ups. I think that means rear-wheel-steer is minimised and grip maintained when really pushing on. 

As ever with Ford, there’s also a financial benefit. They claim such excellence is achieved without the need for a costly and weighty Watt’s linkage. Forgetting fiscal prudence, minimising unsprung weight is a golden rule.

Certainly, the car is impeccably balanced during spirited cornering. You can throw the car around and the tail absorbs bumps without deviation. There’s not the slightest evidence of rear-wheel-steer and grip is maintained, seemingly regardless of surface irregularities, however hard you lean on it. Throughout, but especially on the ragged edge, everything remains playful with continual feel and feedback through the wheel and cosseting Recaro. In fact, there is no ragged edge, the car just behaves, inspiring deep confidence – at least for the driver… quite possibly utter terror for any passenger!

Bottom line? The Fiesta ST is roaring fun at speed or for a leisurely excursion, and for that we have the Ford suspension and damping geeks to thank!

Photography by Joe Harding.