X-ray spec -- McLaren MP4/4
Gordon Murray's move to Woking let him tackle some unfinished business, he tells Keith Howard
Brabham scaled its last summit with Nelson Piquet's World Championship in 1983, after which it proved the maxim that when you've reached the top there is only one way to go — down. So for his last season with the team in 1986, Gordon Murray tried something radical to pluck the irons from the fire: the low-line BT55 with its lay-back driving position and canted-over BMW engine.
It bombed. Murray admits to placing the car's centre of gravity too far forward, so it had "piss-poor traction", and the team suffered mysterious power loss in cornering that was only belatedly diagnosed as oil-surge problems caused by the engine's tilt. Pete Weisman, the American transmission guru who had worked successfully with Murray in the past, had suggested the layout and blamed BMW for a lack of enthusiasm in its last season. When I spoke to his widow Michelle three years ago she was unequivocal: "As far as I'm concerned, that's the reason the car didn't go well — there was just no effort from BMW to make it work."
As if all this weren't bad enough, Elio de Angelis died needlessly in a high-speed testing accident at Paul Ricard in May. He only suffered a broken collarbone in the impact but asphyxiated in the resulting fire because of a lack of extinguishers and an ineffectual fire truck
All told it was a rotten season for both Brabham and Murray. For the former it was the beginning of the end, but in 1988, having moved to McLaren, Murray reasserted his design talent in the most spectacular way imaginable. With Alain Prost and Ayrton Senna driving, his MP4/4 won 15 of the 16 grands prix that season, achieving such dominance that the team amassed a points total only one shy of 200 and just two short of all the other teams combined.
What is even more remarkable about this is that the MP4/4 was, in effect, a BT55 done properly. Because the Brabham had been a failure, nobody in the pitlane had paid it the attention it deserved. Its execution had gone awry, certainly, but its principal features signposted the way ahead. Although the lesson was lost on others, Murray remained convinced that his approach was the right one. As he describes here, everything came together at just the right time for the MP4/4 — and the result was a phenomenon.
"Honda did a great job with the small clutch and lowered crank but it was so low that the driveshaft angles became ridiculous. I decided we needed a bit of genius and phoned Pete Weisman, who came up with an amazing three-shaft gearbox. Half the story of the car is the engine and gearbox, really. I'd first done a semi-dry-sump gearbox in the BT44 in 1974, but there was still a lot of oil in the casing. Pete said, 'How do you fancy doing a completely dry-sump 'box?' He put the transfer gears at the front and designed a close-fitting magnesium cover for them, with the clearances of an oil pump. That was the front scavenge pump. Under braking it picked up all the oil from the gearbox and, without any pipes, moved it to the oil tank just ahead of it. For the rest of the lap we had holes in the bearing bulkheads and a little scavenge pump at the back. It was the first true dry-sump gearbox and it made the most awful racket because there was no oil damping the vibrations. When we fired up the first car in the workshop we switched the engine straight off because we thought it had blown up. At the races we'd start the car on stands, and you could see people from other teams thinking, 'That's not going to last more than two laps'. But even with all that new technology in it, the 'box was reliable. That was Pete's genius."
"Colin Chapman was the first to achieve a 30-degree back angle for the driver with the Lotus 25. But designers, including me, kept sitting drivers up until some were 50 degrees above the horizontal. The driver's torso weight is a significant percentage of the car's overall weight, so this was crazy. If you could lower a gearbox by 5mm you would, but here were tens of kilos much higher off the ground than they needed to be. Ayrton was ultra-competitive so from the beginning he thought the lay-back driving position was great because of its many advantages. But Alain grumbled, so we increased his back angle. He liked that until we ran a wind tunnel test that showed a measurable disadvantage. Boy, did he lie down quickly after that!"
Shallow bodywork emphasises clean run to rear wing due to Murray's 'lay-back' design.
"I always built cars with lots of wheel travel, sacrificing a little downforce by not running the car too close to the ground. That made it more comfortable and easier to set up. During '88, as we gained more downforce through wing development and running a bit lower, we did try running the car more solid, but the drivers hated it. On the front I used a trick that featured on the BT48, where we achieved rising rate using machined roller tracks on the bottom of the damper. The curve of the track determined the rising rate you could have any characteristic you wanted and could change it easily by substituting different tracks. I didn't use much rising rate around the working area but did introduce quite a lot where it was needed to stop the car crashing into the ground. This is one reason why we could run softer. We also used rising rate at the back using a normal pushrod and rocker system."
"I carried the low-line idea across from the BT55 because I'd seen the massive aero benefits. And also partly bruised ego. But a number of things happened at just the right time for us to make a really good job of it. If the engine was already higher than the driver's shoulders then there was no point going low. So I went to see Honda about lowering the engine and found that they were already doing it. This and the smaller-fuel-tank regulation that year allowed us to do a really good job. We reduced frontal area by 10 per cent and lift-to-drag ratio by six per cent, because you could run a very simple rear wing and keep it well clear of the car's upper deck. It was luck, really it just all came together at the right time."
Discipline is the key...
"When I came to McLaren I thought they would have masses of discipline and that they'd analyse everything," says Murray. "At Brabham I'd get everybody together after races to track problems and solve them. We had a detailed life assessment for all parts and we tracked materials carefully. I imagined that at McLaren it would be 10 times better. But there was absolutely nothing like this. I'd ask to see the reliability records from last year -- the log of everything that broke and what was done about it -- but they didn't keep such records. They didn't have meetings after every race because they didn't have a meeting room! When I started at McLaren, Ron (Dennis) said, 'you have carte blanche -- anything you don't like, change. Anything you want, you can have. I want to win championships.' He absolutely stuck to that, and it was key in the MP4/4's success. I built meeting rooms, began to keep testing records, got hold of all the broken bits to analyse the problems. In '87 there were 74 chassis failures, where something had cracked or whatever. In 1988 we got this down to 17."
"When I asked about the torsional stiffness of the '87 tub it turned out they'd never measured it, or the engine or 'box. In fact a lot of the cracking problems they were experiencing were down to monocoque, engine and gearbox stiffness and the junctions between them. In those days they'd lay the tubs up at McLaren and then truck them to the south coast to be autoclaved (cured under heat and pressure). When I arrived I said to Ron, 'Where's the autoclave?' He said it wasn't necessary to have one, but I said that meant letting somebody else have control over the tub's performance. 'If you need one, get one: he replied. So I did. It cost us £450,000!"