Size and weight were preoccupations for the project’s engineers. No one would describe the original MX-5 as large, yet the new model has been made 55mm shorter still. It’s the most compact MX-5 yet and, save for the original, the lightest.
Throughout the development, a rigorous ‘gram strategy’ was applied to ensure that the roadster had no superfluous mass. Thus the all-new suspension, still consisting of front wishbones and rear multi-links, is 12kg lighter thanks to its aluminium components.
The engine frame is aluminium, as are the front wings and bumper reinforcements.
The front cross-member is high-tensile steel, a much higher proportion of which is used in the body, too. The rear cross-member benefits from a more rigid truss structure, while suspension mounts have been reinforced all round. The result is a claimed 100kg reduction in kerb weight compared with the previous MX-5. The additon of the hard top roof to the RF model will increase the overall weight, but should appeal to those looking for a driver's car to use all-year-round.
That presents the prospect of this car being a true sub-one-tonne rear-drive open-top (Mazda quotes the 1050kg kerb weight of the 1.5-litre car to EU standard, adding 75kg for a driver and luggage), without being as stripped out as a Caterham or as overtly spartan as a Lotus. Moreover, the weight is ideally distributed 50/50 front to back and the centre of gravity is slightly lower than before.
Mazda’s seriousness about making this MX-5 fun to drive by adding lightness is welcome – and crucial when you consider that this is the first model to use electromechanical power steering. It’s a compact dual-pinion set-up located close to the front wheels for increased stiffness. It has a marginally quicker ratio than that of the previous car, while the front wheels’ castor angle is increased for better resistance to understeer.
The MX-5’s engines and gearboxes have been made to measure. Despite being used elsewhere in Mazda’s line-up, each is fettled for the MX-5. The 129bhp 1.5-litre Skyactiv-G petrol engine – related to the one in the Mazda 2 and 3 hatchbacks – gets revised cam timing, a custom crankshaft and a 7500rpm redline, while the 158bhp 2.0-litre version adds a lightened flywheel and pistons.
The rear differential weighs less, too (although it isn’t a limited-slip item in the 1.5-litre car tested), as does the six-speed manual Skyactiv-MT gearbox, which, having been made to emulate the MX-5’s shift action in other applications, gets the starring role here with a simplified linkage for even less resistance. Source by autocar.co.uk
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