Pete05
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- Melbourne, Australia
By this time the V16 BRM was no longer eligible for Grands Prix, but it continued to be campaigned in Formula Libre events. It was also further developed and several victories were scored, but all in minor races. Five years after the V16's debut, work was finally started on a new Formula 1 car. This time simplicity was the keyword, but the team still persevered with their founding principle of having every major part designed in-house. There were
a few bits ordered from specialized suppliers; specialized British suppliers of course. At first glance, the resulting BRM Type 25 (not P25 as it is often erroneously called) was certainly a more simple affair, but there were again some unique features that not necessarily improved the car's chances of success.
The biggest contrast to the high revving V16 of the previous BRM was the twin cam 2.5 litre four cylinder, designed from scratch by Stuart Tressillian. He opted for an unusual big bore to allow for very big valves to be fitted. The nationalistic principles were set aside for the twin-choke Webers. The engine was installed in a straightforward steel ladder frame chassis with wishbone and coil spring suspension at the front and a DeDion axle at the rear with a transverse leaf spring. The four speed transaxle sported another oddity; a single disc brake used to slow both rear wheels down. At the front a conventional setup was chosen with Lockheed discs. Cast alloy wheels were used instead of the still very popular wire wheels.
In September 1955 the Type 25 was debuted at a local race at Aintree. It was relatively quick straight away, but there were handling and reliability problems that would dog the car throughout it's career. The big valves were a weak spot and oil and dirt buildup on the single rear brake was another major issue. For 1956 Mike Hawthorn and Tony Brooks were hired, but other than some spectacular crashes, they didn't manage to grab attention. At the end of the season Brooks took off; he didn't want anything to do with the horrible BRM anymore. There were some revisions carried through for the 1957 season, but BRM again failed to impress. To add insult to injury, Vanwall scored that elusive first British Grand Prix win in thirty years.
Still determined BRM carried on into 1958 with some fundamental changes. A more sophisticated spaceframe chassis was introduced and the suspension was modified. Following suggestions made by Lotus' Colin Chapman, the single rear leaf spring was replaced by coil springs on each corner. By now the Type 25's reputation was, however, so bad that the one-handed Archie Scott Brown refused to drive the car, even though he was desperate to get a break in F1. The changes did improve the handling, but results were again poor because the engine suffered from overheating after changing from alcohol-based fuels to pump gas. For 1959 the cooling system was improved and the Lockheed discs were replaced by Dunlop brakes, but the single rear disc retained.
Three years of developing had finally turned the Type 25 into a, by BRM standards, fast and reliable racing car. The car's first victories were scored in non-championship events and then Jo Bonnier finally added that elusive first Grand Prix win to BRM's tally at Zandvoort in 1959. Sadly Cooper's mid-engined revolution meant that by the time the front-engined Type 25 finally came good, it was virtually obsolete.
ENGINE
Configuration
Straight 4
Location
Front, longitudinally mounted
Displacement
2491 cc / 152 cu in
Bore / Stroke
102.9 mm (4.1") x 74.9 mm (2.9")
Valvetrain
2 valves per cylinder, DOHC
Fuel feed
2 x Weber carburettors
Aspiration
Naturally aspirated
Power
275 bhp / 205 kW @ 8000 rpm
Torque
278 Nm / 205 ft lbs
DRIVETRAIN
Chassis
Aluminium body, steelspace-frame
Front suspension
Double wishbones, coil springs over dampers
Rear suspension
DeDion axle, coil springs over dampers
Steering
Rack and pinion
Brakes
Front discs, single rear disc on the gearbox
Gearbox
4 speed manual
DIMENSIONS
Weight
690 kg / 1521.2 lbs
Wheelbase
2286 mm / 90"
http://www.grandprix.com/gpe/con-brm.html
http://www.ultimatecarpage.com/car/73/BRM-Type-25.html
http://en.wikipedia.org/wiki/British_Racing_Motors
