BRM P153: Pedro Rodriguez's final winning F1 car

One of the advantages of working for BRM, says Southgate today, was the huge range of engineering skills available within the parent Owen group. “I had a budget of £25,000 for the 153, but that was purely for things I had to buy in. Anything that could be made in-house was effectively free. If I could have had everything down to the tyres made in-house, the car would have cost nothing.”

Despite the fluid form, Southgate’s light monocoque – weighing 57lb bare – is a straight-sided ‘bathtub’ ending behind the driver. But the V12 was not designed to be a stressed member, so the 153 uses a triangular tubular frame to take some of the suspension loads off the block. This allows the rear suspension to hang off the transmission, with wheel location by a single top arm and a reversed lower wishbone, plus radius arms forward to the monocoque. The front uses a conventional double-wishbone layout, and as if to reinforce BRM’s reputation for the highest engineering quality on the grid, the steering rack and some of the suspension was machined from super-light titanium.

A top outlet to the front-mounted radiator was claimed at the time to provide some measure of downforce on the front axle. “No,” says Southgate. “That car relied on its wings. The top exit was just convenient.”

For 153, Woods had to improve the 48-valve V12’s erratic output. Better-breathing heads and improved cooling made the figures healthier, while reversing the heads allowed the exhaust to exit outside with the induction nestling in the centre. Now the pipes could poke discreetly through the rear suspension, cleaning up airflow to the rear wing. The only element which is less than tidy is the twin oil radiator and L-shaped oil tank above the gearbox. These were forced on the designer.

“To keep the V12 so compact – it was only two inches longer than a DFV – they used narrow bearings which frequently failed, putting a rod through the block. We had about 12 engines, and at one race there was only one without a patched crankcase. The only way we could overcome that was to pump huge quantities of oil round, which meant a large oil tank. We got to 4.4 gallons in the end, and we just knocked up a flat-sided job for speed. I made a much neater one for the P160 when I had more time.”

With these mods the BRM V12 matched a DFV on power, but revved higher, at 11,500rpm. “Which meant we used more fuel,” says Tony. “We’d start with 10 more gallons than them – 48 in total. But it was great for qualifying.”

That slightly melted shape is down to the two bag tanks, one each side, outside the chassis, to lower the centre of gravity and minimise weight shift with fuel usage. It was as much an aesthetic decision as anything else, says Southgate. “My previous car was the ’69 Indy Eagle which had flat-sided tanks because no-one in the States would do compound curves in metal, and it wasn’t very glamorous. In Britain we were knee-deep in men who could bash out curved panels.

But if BRM now had a serious contender, it also had serious opposition. Ferrari’s 312B and Matra’s MS120 both matched it for rev-happy V12s, Lotus was fielding the advanced 72, and everyone else had that field-sweeping wonder, Cosworth’s V8. Still, with Rodriguez and Oliver aboard, and sometimes a third car for George Eaton, its qualifying positions improved race by race, until round four – Spa. From the third row, the Mexican pushed through to take the lead on lap five – and took it to the flag. The drought seemed to be over, but it was a one-off. Often rapid in qualifying, sometimes challenging for points, the 153 repeatedly broke its engine, gearbox or axle, as Oliver recalls. “In the quest to reduce friction they used needle-roller bearings in the hubs, which raised a stress point at the axle neck. So the front wheel kept falling off.” Which caused Oliver to collide with Jacky Ickx at Jarama; both cars burned out.

“I guess we built around five of them,” says Southgate, which makes this one, Chassis 05, about the last. It can’t claim any wins, but it is extremely original. Its debut was the Dutch GP in June 1970, where Pedro Rodriguez placed tenth, but it followed with three DNFs before Pedro scored fourth in Austria. Oliver then took it over, but suffered three more failures before Mexico brought a struggling seventh. With the improved P160 quickly on stream the 153s were retired, and in typical Bourne style, stored. 05 went direct to the Donington Grand Prix Collection from the BRM sale in 1981 and has since been restored by BRM specialists Hall & Hall. Sitting in Donington’s huge museum, gleaming in red, white and gold, it’s a reminder of a flash of hope during BRM’s darker days.