Flat-twin flyweight The brilliant Panhard Dyna Z’s exotic construction precipitated its downfall. Lightly does it. The secret of the all-aluminium Dyna Z Panhard was how little it weighed. Jon Pressnell tells the story of one of the cleverest of ’50s family saloons. Photography Tony Baker.
Panhard’s aluminium-bodied Dyna Z: futuristic marvel or white elephant?
It had to be an alloy car – otherwise I wouldn’t have bought it,” says Bernard Burckel of his 1955 Dyna Z. “When they went to steel it wasn’t a real Panhard any more.” Newcomers to the French marque might be perplexed by such a remark, but Panhard’s switch from making an all-aluminium ‘Z’ to one with an all-steel body was a defining moment in its history.
Announced in June 1953, the Dyna Z was the creative answer to a number of inter-related technical and industrial challenges. Panhard had adjusted to the new realities of the post-war car market by abandoning its extravagant sleevevalve luxury models in favour of the little twin-cylinder Dyna X. But the baroque styling of the ‘X’ and its high price meant that its sales were modest: in its best year, the ’51 season, just 13,422 would be made. For comparison, that year Renault churned out more than 97,000 4CVs.
Considering the conundrum during 1950, Panhard concluded that it needed a car that could be made in greater numbers and that would command a higher price – and thus, in theory, bring in bigger profits. Financial constraints also meant that the existing mechanicals would have to be retained. Meanwhile, if production were to be increased, then the car would have to be designed in such a way that it could happily be produced in the company’s ill-suited Paris factory, where short assembly lines were split over three storeys of a cramped set of buildings.
The answer was to build a larger saloon, one that would fish in the same pool as the Peugeot 203 and the forthcoming Simca Aronde. To offer competitive performance while still using the all-alloy flat-twin – albeit increased in capacity to 851cc – would mean that the car would have to be exceptionally light. Also, in an era where such matters were rarely considered, it would have to be as aerodynamically efficient as possible.
Finally, the construction would have to depart from conventional notions of either a full-length chassis or an equally long unitary body, to enable as many cars as possible to pass down the Quai d’Ivry assembly lines at any given time. Lightness was addressed by making the monocoque out of aluminium. All the strength was in a central punt, ribbed for rigidity and reinforced by three round-tube crossmembers and deep sills. Onto this platform were welded the monopiece side panels, the bulkhead and windscreen bay, and the rear body, leaving the front as a single lift-up assembly that combined bonnet and wings.
The final cleverness was that the running gear – using twin-transverse-leaf suspension at the front and a dead axle with six torsion bars in a vee at the rear – was mounted on two bolt-in tubular subframes. So the space the bodyshell took up as it passed down the line was reduced, up until the moment the subframes were bolted into place. To help the flat-twin cope with a body that was not that much smaller than that of a Renault Frégate, more than low weight was needed. Body engineer Louis Bionier had grasped the importance of aerodynamics after his experiments with the Dynavia concept, and he used the same mixture of wind-tunnel and on-the-road testing to refine the Dyna’s shape.
The quoted drag coefficient of 0.28 can be taken with a pinch of salt, but the fact that on a paltry 42bhp the Dyna managed a top speed not far shy of the claimed 130kph (81mph) is proof enough that the form was aerodynamically effective. “Everything about it was logical,” recalled Jean Panhard, deputy MD at the time of the Dyna Z, in 2004. “We had lots of discussions, Bionier and myself. The two of us established the specification.
Certainly from the engineering point of view it was a quite remarkable revolution. Two years later Jean-Pierre Peugeot said to me ‘You know, when you brought out that car, you gave us a fright’. It was a well thought-out vehicle and very much ahead of its time. A car that did 80mph, weighed 14cwt [711kg] and had six seats and did 40mpg. That was quite something.”
Such innovation could not come cheaply. In 1953 the Dyna retailed at 760,000F in Luxe Spécial form, when a Peugeot 203 was 625,000F and a Simca Aronde 655,000F. For a saloon powered by a sub-1000cc flat-twin, the Panhard looked pricey. It took a more savvy eye to realise that the Dyna had a power-to-weight ratio that was about the same as these two more orthodox and much heavier rivals. The Panhard had a kerb weight of just 1573lb, against 2107lb for the Aronde and 2037lb for the Peugeot. It was clocked by The Autocar at 26.1 secs to 60mph, with a top speed of 75mph. That was faster than the Aronde and the 203, and was achieved with an overall fuel consumption of 34mpg.
Panhard was in with a chance of breaking into the big time, but its brave new saloon was nearly torpedoed as a result of a disastrous miscalculation. “When we worked out the manufacturing costs, we reckoned that the waste aluminium would be taken back by Aluminium Français at the price we’d bought the sheet aluminium,” recounted Panhard. “There was a large amount of scrap, as with all vehicles. With steel this isn’t crucial, because steel is cheap. But aluminium was sold at a high price. This error gave us a cost that was almost unsupportable. It was a monumental mistake. We soon became aware that when they took back the waste they paid roughly five times less than we’d calculated. That error represented our profit margin on the vehicle.”
This is easy to believe. An aluminium body cost roughly three and a half times as much to make as a steel one, Panhard had estimated. The solution was to replace the aluminium with steel. For 1956 the basic shell became steel, but keeping aluminium for the doors, bonnet and boot, and for 1957 the Dyna went over to an all-steel body. The car was ultimately heavier by 150kg, or roughly 330lb. Performance suffered, while the edge was taken off the roadholding by the extra weight over the rear wheels; this was mitigated from March 1957 by the fitment of telescopic rear dampers, following their adoption at the front a few months earlier. Despite 1956-on cars having a stronger and more torquey engine – or perhaps because of it – the press felt that the Panhard had lost its dynamism and was now more a sober family car than a spirited sporting saloon. Performance was deemed gentler and more progressive. In a word, said L’Automobile, the Dyna had become ‘feminised’.
If so, the public didn’t mind – especially because the steel Dyna could be sold profitably for less. Sales shot up, with output more than doubling, from 18,542 cars in 1955 to 37,976 two years later. Production dropped a little in ’58 – unsurprisingly, because the Dyna’s rounded lines were out of step with fashion. Accordingly in June 1959 the ‘Z’ was replaced by the PL17, which had a sharper front and rear but retained the Dyna centre section and its mechanicals – with the addition of a synchronised fourth gear. There was also the option of a 50bhp ‘Tigre’ engine; this made the PL17 an 80mph car.
Helped by a price reduction, sales took off again, with 1960 production of 34,050 cars being the second-highest in the history of the Dyna/ PL17 range. A facelift for 1963 brought with it an all-synchro ’box and an uprated engine, giving 60bhp in ‘Tigre’ form. Manufacture continued until May 1965. That was a pretty good run in anyone’s money, and surely vindicates the realism behind that gut-wrenching decision to abandon the pioneering aluminium body.
All the same, there’s no doubt that the idea of a lightweight, efficient family saloon is at its purest in a fully aluminium car – aesthetically as well as technically, because for 1957 the Panhard’s smooth, neatly styled lines would be broken up by ungainly globular rear lights.
But how, in practice, does an early ‘Z’ rate? Step over the deep sill of Burckel’s Dyna Green car and first you appreciate how well Panhard delivered in terms of interior packaging. There’s generous legroom front and rear, a flat floor, and to add to the feel of spaciousness a faraway padded dash with all the controls clustered in the instrument nacelle. “With three adults it’s tight at the front but with two children it’s fine,” says Burckel, who uses the Dyna Z as everyday transport, alternating with a Mini and a Dauphine.
At rest the flat-twin putt-putters quietly, and it’s unobtrusive around town. It is noisier under acceleration and there’s a certain thrumminess on the motorway, but it never feels overworked. Performance is easy, with 50-60mph painlessly achieved. Bowling along at 55mph, progress is not frantic, wind-rustle is limited, and two people can talk happily to each other.
There is also surprising flexibility: the Panhard pulls from almost standstill in second, and can be trickled along in third. A tolerant drivetrain aids smooth progress, while a firm throttle and a sweet, short-travel clutch make driving agreeable; well-sized pedals help. The column change has an elusive neutral but moves easily from gear to gear; the action isn’t very mechanical, but there’s no flop, and the old dodge of initially slotting into second ensures clean engagement of first. The lack of synchro on fourth isn’t an issue; with a little pause, the lever slots happily into top.
The rack-and-pinion steering is precise without being weighty and inspires confidence. Late PL17 wheels bring with them finned drums that ensure braking that is worry-free if a tad wooden. “The wheels are smaller and a bit wider, and take modern tyres, so they must help roadholding – it hangs on well in corners,” says Burckel. This is true enough, even if there’s sufficient roll to have passengers sliding around if you are overexuberant on motorway sliproads – no doubt the payoff for the comfortable ride. The lightweight body does crash a bit on poor surfaces, though. Steel cars are acknowledged to be more refined, both because of their construction and as a result of improved sound insulation.
“As family transport the Dyna is wonderful,” enthuses Burckel. “When I took it on a camping holiday I realised what an exceptional car it is. It cruises at a genuine 110kph [70mph] on the motorway. It’ll happily do 800-900km [500-560 miles] a day, and for me it’s been reliable. I’ve just done the Stelvio Pass four-up, in company with an Onze Normale Traction Avant. The Dyna went a bit better than the Citroën and used about half the petrol. On long journeys, it does 5.9 litres per 100km [47mpg] or thereabouts.”
The later steel cars made sense commercially, but it is legitimate to regret their compromises. The aluminium-bodied Dyna Z was arguably the most intelligent series-production saloon of its time. That it still impresses with its performance, ease of driving and economy is testimony to the elegant effectiveness of the engineering that informed its creation.
‘THE DYNA MANAGED 80MPH ON A PALTRY 42BHP, WHICH IS PROOF OF ITS AERODYNAMIC EFFICIENCY’