Brabham BT19
The Brabham BT19 is a Formula One racing car designed by Ron Tauranac for the British Brabham team. The BT19 competed in the and Formula One World Championships and was used by Australian driver Jack Brabham to win his third World Championship in 1966. The BT19, which Brabham referred to as his "Old Nail", was the first car bearing its driver's name to win a World Championship race.
The car was initially conceived in 1965 for a 1.5-litre Coventry Climax engine, but never raced in this form. For the 1966 Formula One season the Fédération Internationale de l'Automobile doubled the limit on engine capacity to 3 litres. Australian company Repco developed a new V8 engine for Brabham's use in 1966, but a disagreement between Brabham and Tauranac over the latter's role in the racing team left no time to develop a new car to handle it. Instead, the existing BT19 chassis was modified for the job.
Only one BT19 was built. It was bought by Repco in 2004 and put on display in the National Sports Museum in Melbourne, Australia, in 2008. It is often demonstrated at motorsport events.
Concept
The BT19 was created by Australian designer Ron Tauranac for the Brabham Racing Organisation to use in the 1965 season of the Formula One motor racing World Championship. The BT19, and its contemporary the Lotus 39, were built to use the new FWMW flat-16 engine from Coventry Climax. Only one example of the BT19 design was built, and it never raced in its original form. Climax abandoned the FWMW's development before the end of 1965, their existing FWMV V8 engines proving powerful enough to propel Jim Clark's Lotus 33 to seven wins and the drivers' championship.For 1966, the engine capacity limit in Formula One was doubled from 1.5 litres to 3 litres. It was not feasible to enlarge existing 1.5-litre engines to take full advantage of the higher limit and Climax chose not to develop a new 3-litre motor, leaving many teams without a viable engine for 1966.
The new 3-litre engines under development by competing team Ferrari had 12 cylinders. Jack Brabham, owner and lead driver of BRO, took a different approach to the problem of obtaining a suitable engine. He persuaded Australian company Repco to develop a new 3-litre eight-cylinder engine for him, largely based on available components; the engine would produce less power than Ferrari's, but would be lighter, easier to fix and more fuel efficient.
Brabham cars were designed and built by Motor Racing Developments Ltd., which was jointly owned by Tauranac and Jack Brabham and built cars for customers in several racing series. The Formula One racing team, BRO, was a separate company wholly owned by Jack Brabham. It bought its cars from MRD but Tauranac had little connection with the race team between 1962 and 1965.
At the end of the 1965 season Tauranac was losing interest in this arrangement, reasoning that "it was just a matter of a lot of effort for no real interest because I didn't get to go racing very much" and "I might as well get on with my main line business, which was selling production cars." Although Brabham investigated using chassis from other manufacturers, the two men eventually agreed that Tauranac would have a greater interest in the Formula One team, which MRD eventually took over completely from BRO. This agreement was not reached until November 1965. Repco delivered the first example of the new engine to the team's headquarters in the United Kingdom in late 1965, just weeks before the first Formula One race to the new regulations, the non-championship South African Grand Prix on 1 January 1966. Rather than build a new car in the limited time available, BRO pressed chassis number F1-1-1965, the sole and unused BT19, into service.
Chassis and suspension
Tauranac built the BT19 around a mild steel spaceframe chassis similar to those used in his previous Brabham designs. The use of a spaceframe was considered a conservative design decision; by 1966, most of Brabham's competitors were using the theoretically lighter and stiffer monocoque design, introduced to Formula One by Lotus during the 1962 season. Tauranac believed that contemporary monocoques were not usefully stiffer than a well-designed spaceframe and were harder to repair and maintain. The latter was a particular concern for Brabham, which was the largest manufacturer of customer single-seater racing cars in the world at the time. The company's reputation rested in part on BRO – effectively the official 'works' team – using the same technology as its customers, for whom ease of repair was a significant consideration. One mildly novel feature was the use of oval-section, rather than round, tubing around the cockpit, where the driver sits. In a spaceframe or monocoque racing car, the cockpit is effectively a hole in the structure, weakening it considerably. For a given cross sectional area, oval tubing is stiffer in one direction than round tubing. Tauranac happened to have a supply of oval tubing and used it to stiffen the cockpit area. The car weighed around 1250 pounds, around over the minimum weight limit for the formula, although it was still one of the lightest cars in the 1966 field. The race starting weight of a 1966 Brabham-Repco with driver and fuel was estimated to be around, about less than the more powerful rival Cooper T81-Maseratis.Image:BT19 rear.jpg|thumb|left|250px|alt=Close-up of the rear of a parked racing car; various components are labelled|Rear view of the BT19, showing:
A) Rear outboard coil spring
B) 4-into-1 exhaust from right-hand cylinder bank
C) Right-hand driveshaft
D) Gearbox
E) Reverse lower wishbone, forming part of left rear suspension
F) Upswept rear lip of engine cowl
The bodywork of the BT19 is glass-reinforced plastic, finished in Brabham's usual racing colours of green with gold trimming around the nose. Although the science of aerodynamics would not greatly affect Formula One racing until the 1968 season, Tauranac had been making use of the Motor Industry Research Association wind tunnel since 1963 to refine the shape of his cars. Brabham has attributed the car's "swept-down nose and the upswept rear lip of the engine cowl" to Tauranac's "attention to aerodynamic detail". During the 1967 season, the car appeared with small winglets on the nose, to further reduce lift acting at the front of the car.
Against the trend set by the Lotus 21 in 1961, the BT19's suspension, which controls the relative motion of the chassis and the wheels, is outboard all round. That is, the bulky springs and dampers are mounted in the space between the wheels and the bodywork, where they interfere with the airflow and increase unwanted aerodynamic drag. Tauranac persisted with this apparently conservative approach based on wind tunnel tests he had carried out in the early 1960s, which indicated that a more complicated inboard design, with the springs and dampers concealed under the bodywork, would provide only a 2% improvement in drag. He judged the extra time needed to set up an inboard design at the racetrack to outweigh this small improvement. At the front the suspension consists of unequal length, non-parallel double wishbones. The front uprights, the solid components upon which the wheels and brakes are mounted, were modified from the Alford & Alder units used on the British Triumph Herald saloon. The rear suspension is formed by a single top link, a reversed lower wishbone and two radius rods locating cast magnesium alloy uprights. Wheels were initially in diameter, but soon upgraded to at the rear, and later still 15 in at the front as well. These increases enabled the use of larger, more powerful brakes. Steel disc brakes are used on all four wheels and were of diameter for the smaller wheels and for the larger ones. The car ran on treaded Goodyear tyres throughout its racing career.
The BT19 continued Tauranac's reputation for producing cars that handled well. Brabham has since commented that it "was beautifully balanced and I loved its readiness to drift through fast curves." Brabham referred to the car as his Old Nail; Ron Tauranac has explained this as being "because it was two years old, great to drive and had no vices."
Engine and transmission
Repco racing engines were designed by the leading motorcycle engine designer, Phil Irving, and built by a small team at a Repco subsidiary, Repco-Brabham engines Pty Ltd, in Maidstone, Australia. Repco's 620 series engine is a normally aspirated unit with eight cylinders in a 'V' configuration. It uses American engine blocks obtained from Oldsmobile's aluminium alloy 215 engine. Oldsmobile's 215 engine, used in the F-85 Cutlass compact car between 1961 and 1963, was abandoned by General Motors after production problems. Repco fitted their own cast iron cylinder liners into the Oldsmobile blocks, which were also stiffened with two Repco magnesium alloy castings and feature Repco-designed cylinder heads with chain-driven single overhead camshafts. The internals of the unit consist of a bespoke Laystall crankshaft, Chevrolet or Daimler connecting rods and specially cast pistons. The cylinder head design means that the engine's exhaust pipes exit on the outer side of the block, and therefore pass through the spaceframe before tucking inside the rear suspension, a layout which complicated Tauranac's design work considerably. The engine is water-cooled, with oil and water radiators mounted in the nose.The 620 engine was light for its time, weighing around, compared to for the Maserati V12, but in 3 litre Formula One form only produced around 300 brake horsepower at under 8000 revolutions per minute, compared to 330–360 bhp produced by the Ferrari and Maserati V12s. However, it produced high levels of torque over a wide range of engine speeds from 3500 rpm up to peak torque of 233 pound feet at 6500 rpm. Installed in the lightweight BT19 chassis, it was also relatively fuel efficient; on the car's debut Brabham reported that the BT19 achieved 7 miles per gallon, against figures of around 4 mpg for its "more exotic rivals". This meant that it could start a Grand Prix with only 35 gallons of fuel on board, compared to around 55 gallons for the Cooper T81-Maseratis. The engine had one further advantage over bespoke racing engines: parts were cheap. For example, the engine blocks were available for £11 each and the connecting rods cost £7 each.
The 740 series unit used in the three races for which the car was entered in 1967 has a different, lighter, Repco-designed engine block. It also has redesigned cylinder heads which, among other improvements, mean that its exhausts are mounted centrally and do not pass through the spaceframe or rear suspension, unlike those of the 620 series. It produced a maximum of.
The BT19 was initially fitted with a Hewland HD gearbox, originally designed for use with less powerful 2-litre engines. The greater power of the 3-litre Repco engine was more than the gearbox could reliably transmit when accelerating at full power from rest, with the result that Brabham normally made very gentle starts to avoid gearbox breakages. The HD was later replaced with the sturdier DG design, produced at the request of both Brabham and Dan Gurney's Anglo American Racers team. It later became a popular choice for other constructors.