Technical focus: Mclaren MP4/4
This extract from Haynes’ latest insight into the workings of one of motorsport’s most famous designs examines what made 1988’s MP4/4 so special
When the MP4/4 appeared for the very first time at the now famous pre-season Imola test, it was immediately obvious that the car was significantly faster than both its rivals and the MP4/3B engine-test mule.
The only apparent question mark at the beginning of the season was over reliability – purely due to the lack of pre-season testing miles.
Although there were a few teething problems – notably with the gearchange mechanism and the mandatory Fia-supplied pop-off valves – the car proved remarkably reliable from the outset. Because the car was fundamentally quick, Mclaren was able to maintain its edge throughout the season, so negligible time was spent on development. The majority of the extensive 1988 test programme concentrated on development and reliability of the Honda engine, which proved remarkably robust. Honda’s engine-testing programme in Japan was relentless, with test driver Emanuele Pirro completing around 10,000 miles over the year. Later in the season the team felt able to concentrate its development efforts on the forthcoming normally aspirated car for 1989 – the MP4/5.
With the exception of engine revisions and modifications to the turbo-intercooler layout and air intakes, the car remained fundamentally unchanged throughout the season. The team saw no reason to expend resources and possibly compromise reliability in order to make significant developments to a car that was already the class of the field, as Steve Nichols explains: “We didn’t do a lot of development during the season because the car was very, very good. We were faster than everybody by a long way, and we were concentrating our efforts on the MP4/5, because that was the car of the future. The MP4/4 car was a dead end – we were only going to use it for one year.”
The monocoque geometries for the Mclaren MP4/4’S predecessors – the MP4/2 and MP4/3 – were descended from John Barnard’s original pioneering MP4/1, which featured the first all-carbonfibre (also known as ‘carbonfibre reinforced plastic’ – CFRP) monocoque to appear in Formula 1. Nichols was instrumental in the involvement of Hercules Aerospace with the construction of the MP4/1 monocoque, and Hercules would continue to be involved as the material supplier for the MP4/4 tub, as he explains: “For the early [MP4/1] monocoque, Hercules made the basic components in Salt Lake City – the monocoque shell, the bulkheads and so on. They made them and autoclaved them, and we would receive those basic components and bond them all together to complete the monocoque. At a very early stage we had our own autoclave. In fact, when we moved sites [from the original Boundary Road site to Woking Business Park], they had to tear down the wall of the building to get the autoclave out! By the time of the MP4/4, Hercules were just supplying us with the carbon pre-preg materials [rather than being involved directly in the manufacture].”
Although many of the construction methods employed for previous Mclaren tubs would be carried over for the MP4/4, the monocoque itself was an all-new design to take advantage of the opportunities provided by the reduced fuel-tank capacity and the lower engine and gearbox, plus the requirement for the driver’s feet to be positioned behind the front-axle centreline. The fundamental difference between the MP4/4 monocoque geometry and its predecessors was that the MP4/4 tub featured a flat floor and vertical sides, rather than the ‘V’ profile employed on previous chassis.
By 1988 most F1 teams manufactured their carbon monocoques using a female mould, whereas Mclaren continued to use male tooling (as they had from the outset with the MP4/1). There were three main reasons behind this decision:
• It was possible to make a single-piece monocoque shell – advantageous for overall strength and stiffness.
• By having largely flat panels, it was possible to use a higher percentage of unidirectional (UD) fibres in the monocoque structure, which is beneficial in terms of strength- and stiffness-to-weight compared to woven CFRP (woven CFRP would have to be used for a female-moulded monocoque if the outer monocoque surfaces were aerodynamic surfaces, ie exposed directly to the airflow and not clothed with bodywork, as was the case with some rival cars, such as the Williams).
• Using a flat-panelled monocoque with separate bodywork meant there was some scope to change the outer aerodynamic surfaces if necessary, for the MP4/4 or developments of the car in the future.
MP4/4 was so quick and reliable that it needed negligible development