Porsche RS 61 Wendler
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Car producer : |
Porsche |
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Model: |
RS 61 Wendler |
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Year: |
1961 |
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Type: |
Roadster |
The 1961 Porsche RS60 and RS61 Spyder sports-racing cars were developed from the preceding Type 718 RSK model which had been introduced in 1958 as the Stuttgart company's replacement for its highly successful 550A Spyder sports-racing car.
The new design was based upon a lighter space frame chassis welded-up from narrow-gauge extruded-steel tubing, three lower elements of which promoted the 'K' title suffix. Its lightweight aluminum bodywork was generally lower with an improved aerodynamic drag figure than the RS Spyders. Originally, the RSK carried a regulation windscreen which was a meter wide and 20cm high (39.37 x 7.87 inches). Ahead of its front wheels, the body nose narrowed, carrying its two headlights beneath clear perspex fairings. The engine-oil surface radiator was built-in under the nose which was otherwise perfectly smooth without any large air intakes.
The mandatory spare wheel was housed within the nose, ahead of an 80-litre (17.6-gallon) fuel tank, with racing filler protruding through the front cover. The oil filler was on the right-hand side amidships, just ahead of the rear wheel. Two air intake grilles appeared on the tail section while a four-louvred panel on each body side, ahead of the rear wheels fed cooling air to the large drum brakes.
The RSK's external body shape would be modified several times. Vertical tail fins were fitted for fast circuits and a so-called 'aerodynamic hump' was also tried, both as a fairing behind the driver's head or covering the full width of the cockpit. For some events such as Le Mans in 1958the passenger's seat was covered by a rigid aluminum tonneau panel.
Vehicle weight was just under 530 kg (1,168lbs) and, in contrast to the 550A, the RSK's front suspension was much improved, with less-offset trailing arms to match longer torsion bars and hub carriers pivoting on spherical joints instead of multiple bushes. The steering column had two universal joints to permit a centerline steering gear mounting, actuating two symmetrical track rods. A left-side driving position was retained, but a true centerline steering wheel/seat combination could be easily achieved for speedy conversion as a 'streamline-bodied' Formula 2 einsitzer.
Rear suspension was by variable-rate coil springs with concentric telescopic dampers, while suspension travel was increased with low-pivot swinging half-axle geometry. Each half-axle was further located by a longitudinal Watt's linkage to avoid toe-in vagaries. Angled 'Turbofins' helped cool the car's four drum brakes.
Power was provided by a Type 718 flat-4 air-cooled engine developed from the successful 550A unit. Output had been increased to an initial 142bhp at 7,500 rpm, while a year's further development would provide 148bhp at 8,000 rpm. In racing, the Porsche RSK drivers were given a rev limit of 7,600 for any appreciable time, but 8,000rpm in urgency. Two down-draught twin-choke Type 40 DCM carburetors, were later replaced by for 46 IDMs.
Transmission was via a single dry-plate clutch and five-speed transaxle gearbox with the four upper ratios synchronized. A vast choice of gearbox and final drive ratios was available.
For 1960-61, the succeeding Porsche RS60 and RS61 models evolved as new variants of the previous 718 RSK. Their aluminum two-seat Spyder bodies were subtly reshaped in light of past experience and to match progressive regulation requirements. The cars' smoothly rounded nose sections were pierced by neat intakes to cool engine oil and the front brakes. A new rounded, lowered nose treatment was also adopted while the redesigned bodywork featured completely detachable front and rear 'clamshell' sections. Two fuel tanks in the nose provided a combined capacity of over 80 litres (17.6 gallons). A head-fairing appeared as standard behind the driver's head.
Two large grilles were incorporated in the tail and enough space was provided behind the engine to hold the mandatory 'regulation suitcase'. For Le Mans a new body was also developed, looking rather like a flat, elongated coupe with the roof panel removed. A true Le Mans Coupe version was also developed, its lower panels identical with the RS61, but a truncated hardtop was added with its rearmost extremity above the rear axle line.
Front suspension was by twin trailing arms suspended by transverse laminated torsion bars. Wishbone rear suspension featured co-axial coil-spring/damper units, the dampers being twin-acting Konis front and rear. Tire dimensions were 5.50-15 R at the front and 5.90 or 6.00-15 R at the rear, mounted on 4.00 J x 15 alloy rims.
The engine in these models was Porsche's Type 547 four-cam 4-cylinder air-cooled unit, enlarged from 1500cc to 1587cc in the definitive RS61. The smaller variant produced "an honest" 150bhp at 7,800rpm while its 89cc larger successor achieved around 162bhp at the same crankshaft speed. Compared with the preceding models the RS60/61 crankshaft was of a stronger design, with roller-bearing big ends while the built-up crankshaft itself ran in three roller-bearing and one ball-bearing mains. Valves were operated by twin overhead camshafts per cylinder bank, and the power units breathed through two twin-choke Weber 46 IDM 1 carburetors.
