AUTOMOTIVE DESIGN
The new 10-spoke ultra-lightweight forged wheels
traditionally a problem for sports car manufacturers due to the amount of strength – and therefore weight – needed to be put into the floor. Not with the 750S, however. Te
The new 750S is the lightest series production vehicle ever made by McLaren
BODY WORK Another area where weight has been restrained is the body. It’s a very complex shape, designed with aerodynamics in mind, but it is not heavier than the 720S. Te company has vast experience with composites, having introduced its first carbon fibre chassis into Formula 1 in 1981 with the MP4/1. For construction of the new car,
Holford notes, “Te body is comparable on weight to the 720S. We do not use a single process to produce all of our carbon fibre components, each component is evaluated individually to ascertain the most appropriate production process to achieve the required properties and production volume. Te car utilises leading manufacturing technologies and materials within our supply base to optimise the component design within the framework of the vehicle’s air management. Within programme design reviews and utilisation of CAE tools, the team optimised the system whilst keeping to the stringent weight targets.” It was important for McLaren to be able to offer an open-topped version,
Spider variant has a DIN weight of 1,438kg, 30kg less than the 720S Spider. “Te only weight added is for the retractable folding hard top mechanism,” observes Holford. “Tat is due to the strength and rigidity of the carbon fibre monocoque used in McLaren supercars, meaning that additional reinforcing is not required – just a rollover structure on the Monocage II-S used for the Spider in lieu of the overhead structure on the coupe’s Monocage II monocoque.” Tis means the Spider is only 49kg heavier than the coupe version.
EVERYTHING, EVERYWHERE Te team really pushed the boundaries with their attention to detail, Holford explains: “Te instrument display is a different design to the 720S and weighs 1.8kg less. Te windscreen glass is thinner, saving 1.6kg.” Te new carbon fibre- shelled racing seats are a combined 17.5kg lighter than the base seats in a 720S. In fact, there are further options for seating, with the passenger seat coming with rails or fixed in place. Super- lightweight carbon fibre racing seats can be specified, these are a third lighter in comparison with the same seat shell produced using conventional carbon manufacturing techniques. Each shell weighs just 3.35kg. Te suspension is a new design, softer
at the front and stiffer at the back than the outgoing model, with a new method of tuning: adjusting the accumulators in
the struts. “Te four damper assemblies together are 2kg lighter – the weight is saved in the spring used,” says Holford. Te wheels also received a lot of attention. Saving 13.8kg over the previous design, the new 10-spoke ultra-lightweight forged units are the lightest ever fitted as standard on a series-production McLaren. Holford explains, “Te team were tasked with a design to push the boundaries of spoke and rim thickness through CAE modelling, optimising the ability to accommodate impact and stiffness targets for NVH and dynamic targets. And blending an aesthetic design at the same time.” Titanium wheel bolts are optional. Te weight targets have been met, with 30% of components new or changed, and the manufacturer has such confidence in the design that the three-year unlimited mileage warranty can be bumped up in 12- or 24-month chunks until the car’s 15th birthday.
As well as the most lightweight, the 750S is also the most powerful series production car produced by the company
For more information visit
www.mclaren.com
www.engineerlive.com 7
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