FROM MEMORY it is difficult to recall a. Grand Prix paddock that had as much mechanical interest and new things as Kyalami had before the South African Grand Prix. There were two makes new to Grand Prix racing, new cars from five established builders, three new engine designs, and of the twenty-three cars entered fifteen of them were brand new and entering their first race.
There were five March cars, all 701 models as seen at the Press preview day at Silverstone and featured in last month’s issue, the Tyrrell team having numbers 701/2 and 701/4 for Stewart and Servoz-Gavin. These cars were painted a rich blue and were running on Dunlop tyres, the Birmingham firm supporting the Tyrrell team again this year. Once the basic monocoque had been finished by March Engineering Ltd. the Tyrrell mechanics did the final building and assembly and there were numerous small differences from the works March cars, such as the run of oil pipes, unions and fittings, the bracing struts for the rear aerofoil, exhaust pipe mountings, oil-radiator mounting, and so on which the Tyrrell team had made or modified in the light of their personal experience. The March east-alloy wheels are held on by a single simple SAE thread out and the Tyrrell mechanics were using a pneumatic-drill spanner, driven by air pressure from a bottle in the pits; to undo and tighten the nuts. While Stewart and Servos-Gavin were chopping and changing tyres during the three practice sessions this speedy mechanical method of undoing the wheel nuts was a boon to the mechanics; until just before the end of the third session When someone got the nut cross-threaded on a rear hub on Servoz-Gavin’s car and the power-spanner made a mess of the nut and the axle-shaft thread. With the continual taking off and putting on of these line-thread nuts it was no surprise that in the intense heat of the sun and the rush and panic of final practice that someone finally made a mistake.
In addition to the five interconnected bag fuel tanks in the March monocoque there are two additional tanks in the form of panniers, one each side of the cockpit. These tanks are of the rigid cellular type, rather than the more popular collapsible rubber type, and have an outlet midway which is attached to a pipe sticking out of the side of the monocoque. The tank is inside a fibre-glass moulding, in the form of an aerofoil, and this is attached to the monocoque by a ring of bolts. As the race distance and fuel requirements were not excessive at Kyalami, Tyrrell raced Stewart’s car without the panniers, and Servoz-Gavin’s with them; in the race itself, Stewart preferring to forgo the added aerodynamic down-thrust they were claimed to Provide for cornering, for the lighter weight and lower drag achieved by not using them. Dunlop provided a very special set of “sprint tytes. in practice for Stewart, On which he ran when he got pole-position, but he did not race on them. For the final practice session and the race he had a brand new 70 series Cosworth V8 engine, but the track conditions and the advantage the Goodyear-shod runners had on traction nullified any benefit Stewart might have had with the latest engine, so he was content to use 9,500 r.p.m. instead of the full 10,000 r.p.m.
The works March cars were all running on Firestone tyres and much time was spent worrying over the very high temperatures that were being recorded after a few fast practice laps. Part of the original STP deal was that the cars should be turned out in a bright “dayglow” red-orange colour, but delay in delivery of this special Granatelli paint from America meant that two of the cars had left for Africa before it arrived, so only the final monocoque of the African series of cars was painted the right colour, and this was Siffert’s car 705/5. The other two were a normal healthy red colour, where they were not covered by advertising stickers. Amon drove 701/1, the car that Was demonstrated at Silverstone, along with 700/2 which Stewart had demonstrated, while Andretti drove 701/3 which had been sent to Africa by boat as a kit of parts and the mechanics assembled it in Johannesburg, but there were one or two headaches when some of the parts did not fit properly, as with most kit cars, though the problems were soon overcome. Each of the three works cars is the responsibility of its chief mechanic as far as detail work is concerned, so that they fit and make things to their own ideas, always providing the designer approves. The combination of car, driver and mechanic must be homogeneous and just as a driver has individual ideas on certain details, so does a chief mechanic, so that, as the Tyrrell cars had touches of individuality from the basic design, so had the three works March cars. This is all right up to a point, such as when a mechanic is ill or leaves the team, or if a time problem should require shift-work. The Mercedes-Benz team, and the Vanwall team when it reached its peak, used to pride themselves on the tool-room fit and standardisation of all parts of their cars so that any mechanic could fit any part to any car. On the works March cars the wheel nuts are tightened with a torque-spanner, set to 140 ft. lb., though they started at 170 and by trial-and-error have reduced the setting. The wheel itself is located by three pins, though these do not transmit the drive, the pressure of the tightness of the nut being sufficient to transmit all the drive forces.
On the day before official practice began Andretti tried too hard and crashed, spinning off the track backwards into a bank, and the shock pushed the engine unit into the back of the monocoque, as well as flattening things like exhaust pipes; oil tank and suspension members. There was another monocoque back in England, the bare hones of 701/6, but rather than rush that out to Africa, the crumpled one was successfully straightened. This was done by an aircraft firm at Rand Airport, just outside Johannesburg, even though they had no experience of racing cars, but they knew about aluminium and riveting and aligning. Meanwhile a March mechanic flew out with an enormous overload of personal luggage in the form of suspension parts and chassis fixtures, and the car was ready in time for the final practice; using a borrowed engine.
All the March cars suffered from too much heat in the cockpit so modifications had to be made to all the fibre-glass nose cowlings to improve the air-flow out through the radiator duct and to provide external scoops to deflect air into the cockpit. The original design provided a hole under the nose with flexible trunking taking it to an aperture in the front bulkhead by the driver’s feet, but this proved insufficient in the African heat. Fortunately Peter Jackson of Specialised Mouldings, Who make 85% of the Grand Prix car bodies these days, was out in Africa on a “sort of holiday” and had a fibre glass kit with him “just in case”. Apart from modifying all the March nose cowlings, and the ERMs, he also remade the seats for
The revived Matra Grand Prix teem, now running under the Simca banner since their merger, had two new cars, for Beltoise and Pescarolo. The cockpit is formed in the monocoque centre section, which is of riveted construction and very angular in shape, built in the form of two boxes, containing rubber fuel cells. At the rear of the cockpit the structure forms a box-section hoop behind the driver’s head and the front of the V12 engine pokes into this hoop. The engine has been redesigned so that the crankcase can act as the rear part of the chassis and, like the Cosworth V8, it is attached to the monocoque by four large Allen screws. The inlet ports are down the centre of the vee of the engine, with exhaust ports on the outside, in a conventional manner, and the fairly orthodox rear suspension is hung on a cross-member over the Hewland gearbox and a small tubular structure bolted under the gearbox, this carrying the parallel lower suspension arms of the BRM-like layout. The rear hub carriers are unusual in that the suspension pick-up points are well forward of the axle centre-line, and the hub shafts are in the form of very large diameter tubes, rather than solid spindles, with the ends formed to carry the 5-stud wheel fixings. The rear brakes are mounted fully inboard, on each side of the gearbox, so that rear unsprung weight must be at a minimum, each bank of cylinder exhausts through six pipes that merge into one long tail-pipe running low down under the suspension. The front suspension consists of a wide-base lower wishbone supporting the external coil-spring/damper unit and a single transverse top link located fore and aft by a short radius arm running back to the chassis from a point about two-thirds out along the link. Much of the geometry and suspension layout is taken from last year’s MS80 and due to the V12 engine layout the wheelbase is longer than most Grand Prix cars, and to keep the track-to-wheelbase ratio to the desired figure the track is very wide. This has allowed the radiator nose cowling to be very wide and flat and to present a large down-thrust area to keep the front end pressed on the ground. Beltoise drove the first car, that did all the prototype testing, and Pesearolo drove the second car, which was brand new, for the race.
The McLaren team had two brand-new M14A models which are a logical development of the first successful Grand Prix car, the M7A, and the Formula 5000 type development the M7C. One major alteration on the new cars is the adoption of the fully inboard mounting of the rear brakes, as on the Matra, the Hewland gearboxes used having lugs cast in that can be drilled and tapped for mounting the calipers. Moving the brakes inboard was done to reduce unsprung weight but it brought an additional advantage. It permitted the use of an ingenious, if somewhat unorthodox, hub layout and the use of drive shafts with no sliding splines or rubber doughnuts. The lateral movement at the hub when the fixed-centre shaft rises and falls under suspension movement is taken up by the hub shaft moving in and out on the actual rollers of the wheel-bearings. The movement is only in the order of 40 thou, between full bump and full droop and a sideways sliding of the rollers on their tracks looks after this. The bearing manufacturers could not offer any concrete objections to this idea so McLaren tried it and it works, saving a lot more unsprung weight and offering a much simpler layout all round. With an outboard-mounted disc brake you could not do this as the disc would have to move in and out with the wheel and there would be no way of locating the brake caliper. Two items of interest in the McLaren cockpit are a switch marked LIM and a large orange warning light to the right of the instrument panel. The switch cuts out the Lucas limiter which “fades” the ignition when peak r.p.m. are reached. From experience, McLaren has found that the settings of these limiters are not always spot-on or they can alter of their own accord. By intelligent use of the switch and the tachometer he can guarantee to always have maximum permissible r.p.m. available. This is not something you would give to a hot-headed tearaway who never reads his instruments or doesn’t have to pay for his own engines. McLaren’s engines belong to him so he is not going to abuse them and he has confidence in his team-mate Hulme. The orange warning lamp in the cockpit is wired into the oil-pressure system and set at a predetermined low figure of around 45 lb./sq. in. On a twisty circuit, or if you are in a close battle with other cars, you haven’t always got time to read the oil-pressure gauge, so if the pressure is sagging at a crucial moment the orange light will come on before disaster arrives. On Hulme’s car, which was the second of the M14A series, the steering wheel has the lower part of the circle flattened, which gives him more space for getting in, and, more important, for getting out in an emergency. They are a cautious lot the McLaren team, which is all part of their professional approach to their business, which is motor racing.
The car that McLaren raced last year, known as the M7C and which had a monocoque on the lines of their Formula 5000 car with the structure forming a bridge behind the cockpit, was bought by Surtees during the winter. Team Surtees rebuilt it with a number of their own modifications which included moving some of the suspension pick-up points, adapting TS5-type hubs and wheel centres so the car, using split-rim wheels like the Chaparral used to have, and moving the scuttle fuel tank and fitting pannier tanks on each side of the cockpit. The car is finished in red with a broad white arrow along the centre from nose to rear aerofoil.
The only works team that did not produce new designs for the first race of 1970 was Gold Leaf Team Lotus, but by all accounts their new one will be well worth waiting for. For the South African race two old 49B cars from last year were rebuilt and the front suspension was altered to save some weight and use 13-in. diameter wheels, the use of which permitted wider rear tyres to be used as well. The front suspension upright is a welded fabricated structure and new, very large diameter hubs are used with a 4-stud wheel fixing. These modifications uprate the car to 49C and as well as the two works cars, R6 and R10, the Rob Walker car R7 and the Dave Charlton car R8 had also been uprated to 49C.
The two works Brabham cars were BT33 Models, of the new monocoque construction, Brabham himself having a brand new one, BT33/2, and Stommelen having the original car, BT33/1. The first car, illustrated last month, used rear suspension hub carriers of BT26 pattern, but the second one had the redesigned pattern which is smaller and will permit the use of 13-in. rear wheels, to match up with the 13-in, front wheels. The Brabham colours for this year are turquoise with a yellow nose band and a yellow stripe down the centre, yellow nose fins and a yellow rear aerofoil. On Stommelen’s car, in recognition of the German sponsor, the upper half of the body, the fins and the Aerofoil are all white.
Although Ferrari had two entries and two cars, only Ickx drove and he rang the changes on the prototype car 312B/001 and a new one 312B/002. These were the new model with flat-12-cylinder engine hung below the backbone extension of the main part of the chassis, which is fabricated from a combination of small-diameter tubing and aluminium panelling making a stressed-skin structure. The engine is surprisingly compact, the cylinder heads having single-piece covers over the two camshafts, the valve angle being narrow, with the inlet trumpets above the engine and the exhaust ports underneath. Although the whole power unit appears to be low, the heaviest part, which is the crankshaft, is quite high off the ground, compared with a vee engine. Front suspension follows previous Ferrari practice, of wide-based lower wishbones and upper rocker arms with inboard spring units, and the forward end of the chassis structure ends in a wedge shape, on which the radiator is mounted. The cockpit is of the semi-open tub layout with a top cover that carries a large flat Perspex screen. The rear aerofoil is mounted quite a way forward, on the rear stay of the crash-bar hoop, and is fully adjustable, with leading edge slots as well as trailing edge ones. On each side of the gearbox is an oil radiator covered by a forward-facing air duct, and the oil tank surrounds the gearbox with the filler under the right-hand radiator duct. On 002, which was used for practice on the first two days, there was an extra oil tank mounted on top of the gearbox, between the radiator ducts, and a large-bore pipe connected this supply to the main tank. In the pipe was a large plumber’s tap operated by a piano-wire control near the driver’s left shoulder. Oil consumption on the flat-12 is obviously high. For the last practice this system was fitted to 001, and it was also used in the race. Above the gearbox is mounted the MareIli Dinoplex transistorised ignition equipment and a battery master switch in the form of a small lever. This lever has a piano-wire control running up to the left of the instrument panel, to another lever that sticks out through a slot in the cockpit cowling. This means that mechanics or helpers can operate the master-switch from the rear or from the left side of the car, while the driver has an emergency push-button in the cockpit that not only actuates the fire extinguisher system, but also operates the master-switch by means of the cable. The front brakes have cooling air ducts cast into the front uprights, as are the steering arms, while the rear brakes are mounted just inboard of the hub-carriers, and there are four exhaust tail-pipes amongst the rear suspension members, which are pretty orthodox. Needless to say the Ferraris are red, though the nose fins, the aerofoil and the oil-radiator ducts arc white.
True to their word after their preview, BRM had two new cars in Africa, 153/01 for Oliver and 153/02 for Rodriguez, while there was one of last year’s cars for George Eaton, this being 139/02. Since the preview the rather fragile-looking casting between the engine and gearbox had been reinforced with plates riveted over the openings. The new engines, with redesigned valve layout and the inlets in the centre of the vee and exhausts out each side, sounded crisp and showed promise, but before practice began the first car was in trouble with a hub shaft breaking, and it happened again at the beginning of the first practice, so the second car was withdrawn and they missed two lots of practice until modified shafts were flown out and fitted. Even then their troubles were not over, for though they turned out for the final practice session the oil tank on the first car split.
The last of the new cars was the De Tomaso which Frank Williams was running in conjunction with the small Italian factory in Modena. With co-pperation from the local Campagnola casting firm Alessandro de Tomaso has been using magnesium castings as the basis for many of his designs (at one time he even produced a complete cast monocoque), and the new Formula One car was no exception. A large and complex casting forms a central bulkhead from which a Cosworth V8 engine and Hewland gearbox are hung, while the aluminium monocoque centre section extends forward from this bulkhead to another casting in front of the driver’s feet. The chassis cross-section is pear-shaped, the cockpit sides not only bulging to accommodate the fuel bags, but sagging downwards to keep the weight low. Suspension front and rear follows orthodox Formula One thinking, and is not unlike last year’s Brabham layout, with exposed spring units at the front. Wheels are Campagnola cast alloy of 13 in. diameter at the front and 15 in. diameter at the rear, with large single nut centre-lock fixing. While the central cast bulkhead is an interesting piece of design, incorporating an extension at the bottom to take the lower engine mounts, and an integral bush for the gear-linkage rod to pass through and so on, it would appear to be a rather vulnerable component that would have to be replaced completely if it suffered any damage, unlike a fabricated structure that could be taken apart and repaired. The designation of this De Tomaso-Cosworth V8 was 505/38/1, the three groups of numbers being respectively the total of all cars built by De Tomaso the design number and the category, i.e., Formula One.
The remaining three cars in the entry list were old but nonetheless quite Competitive Formula One cart, all turned out in a most immaculate condition, and they would have been a credit to any Grand Prix grid. Team Gunston, backed by the Rhodesian Tobacco Company had an early Lotus 49 to “B” specification for Love to drive, and this had their own idea of exhaust pipes for the Cosworth V8 engine, in which the four-into-one on each side curled up and over the rear suspension. The second car was the Brabham-Cosworth V8 that Frank Williams built for Courage last year, though when delivery was made to de Klerk, the driver, some vital parts were missing, and the aerofoil for example had to be made out in Johannesburg. Both these cars were in the orange and brown colours of Team Gunston and were well prepared. The last entry was a Lotus 49C that began life as the car that Bonnier wrecked in practice for the Gold Cup last year but a complete rebuild at Lotus did not leave much of the original car. Entered by a local racing enthusiast, Aldo Scribtante, the car was finished in orange and blue and Charlton was the driver.—D. S. J.
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