The unloved car that nearly cost Senna a title

A major mid-season upgrade from McLaren doesn't sound like anything out of the ordinary today. In more humble times three decades ago, it was a big undertaking, yet that's what was required for the team to complete a hat-trick of world championships and Ayrton Senna to claim a second title in the face of a resurgent Ferrari in 1990.

McLaren didn't see reason to change a winning formula for that season. Its first normally aspirated Honda-powered car had won 10 of the 16 races in 1989, and so the MP4/5 morphed into the MP4/5B.

"We didn't consider anything else," says Neil Oatley, who led the design of both cars. "The basic chassis and layout were good, so we effectively fitted a different aero package to what we had."

There were two problems facing McLaren in 1990. Ferrari, now with Alain Prost on its driving strength, was getting ever stronger and McLaren got those aerodynamic revisions wrong. A new multi-arched rear diffuser had shown promise in the windtunnel, but that was not always replicated out on the track. Senna and new team-mate Gerhard Berger reported a car that was both nervous and inconsistent.

"The arched diffuser looked like the bee's knees in the windtunnel," explains Tim Wright, Berger's race engineer in 1990. "The problem was that it was very sensitive in yaw [a sideways movement].

"The car would get halfway through a quick corner and become unstable at the rear. We could get the thing to work on a qualifying lap, but over a race distance the performance would deteriorate because we would struggle on the tyres."

Things came to a head in mid-summer, resulting in a poor run of results at the French and British Grands Prix. Prost won both races and Senna could finish no better than third on each occasion.

"In the test prior to Silverstone, we weren't particularly competitive and in the race we struggled again," says Oatley. "We felt that to keep Ferrari at bay we needed to do something significant."

The MP4/5B probably doesn't sit up there with its two predecessors in the pantheon of great McLarens

That's significant, stresses Oatley, by the standards of the time. "The developments were nothing like we would do today," he says. "It was based on parts that we had to hand or stuff already in the process."

The arched diffuser had gone by the time the F1 circus arrived at Hockenheim for the German Grand Prix in July and Senna duly returned to the top step of the podium and set Oatley's MP4/5 concept on course for a second title.

Oatley almost didn't get to design the V10-powered McLaren-Honda. The initial plan had been for chief designer Steve Nichols to take charge of a project that had started almost at the same time as the 1988 MP4/4.

"Ron Dennis wanted to divide everything into two teams, one to do the 1988 car and one the '89 car," says Nichols, who departed McLaren for Ferrari at the end of '89.

"I said to Ron that I'd do the '89 car because that was the future. He came back to me after a couple of days and explained that, since we only had six months, I should do the MP4/4 because I'd been at the team longer and knew the people and the systems."

The plan was to have a V10-engined mule car up and running by the summer of 1988. McLaren achieved that target with the MP4/4B, a better car than the MP4/5 according to some at the team at the time.

The MP4/5B probably doesn't sit up there with its two predecessors in the pantheon of great McLarens, but that doesn't concern Oatley.

"The MP4/5B was never as dominant as the 4/4 or even the 4/5 in 1989," he says, "but it achieved its aim and won the championship."

Long legs hinder Berger

When new McLaren signing Gerhard Berger didn't quite fit the MP4/5, it wasn't a problem.

The team in the field simply moved the pedals to make him comfortable for the winter testing programme. There was one problem, however: no one told the design office.

Matthew Jeffreys, who was largely responsible for the design of the monocoque, explains: "The pedals had been moved into what would have been an illegal position in front of the axle line. When the 1990 car was already designed, we realised we had an issue."

That resulted in modifications to the steering bulkhead to give Berger's legs more room (above). Without these changes, he would have failed the extraction test that demanded the driver retract their knees without fouling the bulkhead.

It wasn't Berger's height that was the problem, but the length of one key body dimension: "Gerhard has very long femurs," explains Jeffreys.

The cramped cockpit conditions and an uncomfortable driving position were at least partly to blame for Berger hitting the barriers after qualifying on pole on his McLaren debut at the United States GP at Phoenix. He had accidently snagged the brake pedal while running second.

A series of minor adjustments to the cockpit and his seating position made Berger much happier by mid-season, though Jeffreys suspects there was another reason for his disquiet.

"Most of all," he says, "Gerhard was probably unhappy with the pace of Ayrton Senna."