Porsche’s First Semiautomatic Gearbox: 1973 Porsche 911 2.4 S


The 911 2.4S in front of me sits resplendent in the summer sun, its rare Gold metallic paintwork shimmering in the light. Our photographer, Dan, is laying on the concrete floor beside me, camera aimed upwards at the front of the car some ten yards away. Disturbed only by the intermittent clicking of his camera as Dan grabs a few variations of his shot, my thoughts are lost in sheer admiration of the Porsche. “That thing’s bloody gorgeous,” I eventually blurt, my mind won over by the purist 911 silhouette, black horn grilles – as per the 2.7 RS – and protruding front lip spoiler, all hallmarks of the 911S (at least in 1973 form) that make it a real Total 911 favourite.

However, though original, this 2.4S isn’t totally in keeping with previous examples we’ve been used to driving. There are no notable deviances externally, and even when peering inside the spec looks refreshingly similar, with lavish use of leather on the steering wheel, dashboard and seats. The difference, if you’ve a keen eye, centres on the gearbox. Despite there being a H-pattern gearlever rising gallantly out of the floor ahead of the front seats, a glance in the driver’s footwell reveals the omission of a clutch pedal. This, then, is a 911S with Sportomatic transmission. Sportomatic was Porsche’s first semi-automatic gearbox, introduced to the 911 lineup in 1967. Despite outwardly being at odds with what was quickly garnering a reputation as a proper driver’s car, it has to be said the gearbox arrived on Porsche’s new icon in good form, a Sportomatic 911R triumphing at the 84-hour Marathon de la Route of 1967 at the hands of Hans Herrmann, Jochen Neerpasch and Vic Elford.


Intended primarily for the US market, which was beginning to show signs of aversion to changing gears using a foot-operated clutch, the Sportomatic unit was essentially the coupling of a 915 gearbox to a hydraulic torque converter (instead of a flywheel) via a vacuum-operated single-disc dry clutch. The clutch is decoupled as the driver touches the traditional hand-operated gearlever, activating a micro-switch that triggers the process. A conventional clutch pedal is therefore not necessary. The Sportomatic ‘925’ gearbox was a sales success at the time, however, no end of pre-impact bumper 911s have since had the four-speed unit swapped out in favour of a more conventional 915 manual – and I’m eager to find out why. My mission today is therefore quite simple: does the Sportomatic gearbox really detract from the early 911 driving experience? With the static pictures taken care of, it’s time to drive. Hopping into the car and taking my place at the helm of the driver’s Recaro Sports seat, I’ve already found a minute difference in front of me; the temperature gauge to the left of the tacho is dissimilar to manual cars in that, instead of denoted temperature markings, there are a range of bars (this is because the Sportomatic encounters higher temperatures in hot climates due to the torque converter sharing the engine’s oil supply). Turning the key, there’s no difference to any behaviour or sounds, the flat six catching and firing vibrantly to life.


From here though, the usual 911 etiquette for moving away is altered somewhat. With no clutch pedal to depress, I put my foot on the brake, grab the gearlever and move it from ‘P’ – for park – situated where the first ratio resides on a conventional manual 915, down and right to ‘D’, for drive (first gear here is technically ‘L’ for low, which Porsche only recommends using on less than favourable terrain as the ratio is so short). There’s a slight baulk through the transmission tunnel as the new gear is engaged and, as I remove my right foot from the brake pedal, the 911S begins to roll forward.  Rotating at the heel of my right foot, I push down on the accelerator pedal – lightly at first – as I swing the S round and through a gate from our location to the main road. I soon find that the Sportomatic responds well to affirmative pedal inputs, as lightly caressing the accelerator does little other than slip the clutch with minimal progress made along the road. With a good prod and ensuing boost in revs, however, the S springs forward positively. We’re away.

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