The new Mazda MX-5 made its first public European appearance at the 2014 Paris Motor Show, bringing a lighter car than the outgoing model, powered by a new 1.5-L gasoline engine (the U.S. and possibly other markets will get a 2.0-L engine, according to industry reports). Mazda is giving few powertrain details away at this stage, but a six-speed manual transmission will be offered. Mazda’s SkyActiv technologies are used in both vehicle design and construction as well as the engine.
Compared with the outgoing model, the new MX-5 is 105 mm (4.1 in) shorter, 20 mm (0.8 in) lower, and 10 mm (0.4 in) wider. The wheelbase is also shorter by 15 mm (0.6 in) at 2315 mm (91.1 in), while both front and rear overhangs have been reduced by 90 mm (3.5 in). Overall, the car is 50 mm (2.0 in) shorter than the first generation MX-5.
Not surprisingly, Mazda has retained the existing format for the car with front mounted engine and transmission and rear-wheel-drive. Similarly the two-seat open bodywork is retained.
With driving the sharp focus for the MX-5, the Paris Show booth included a chassis assembly of front and rear suspension with engine and transmission and bracing section between transmission and rear axle. There are many similarities to the technology used on the outgoing model, but the components are new.
“The format of the rear suspension is the same as the third generation, the multilink, but what has changed is the position of each of the links”, Mazda MX-5 Program Manager Nobuhiro Yamamoto told Automotive Engineering. “I can’t discuss the geometry, but the suspension crossmember goes underneath the differential, while on the third-generation model, it was fitted over the top. The reason is quite simple. It’s going back to the fundamentals, because the crossmember has to be reacting to the input that’s coming from the links and it needs to provide that rigidity. So rather than going over the top, if the crossmember goes underneath, which is closer to the vector where the forces are coming in, it makes it simpler, you can make it lighter, yet it will still give enough rigidity. SkyActiv technology is going back to basic principals, and that’s what gives us the ideal form.”
Mazda has continued with double wishbone suspension at the front: “At first glance, it might not look as though there have been changes, but there are,” said Yamamoto. “As with the rear, we have changed the geometry, and it’s important to make the unsprung weight as light as possible, so the upper and lower arms are made from aluminum.
“The steering knuckle on the third-generation car was made from steel, but on the new car, it’s made from aluminum, so it’s lighter but still has high rigidity. Up to the third generation, we used what we called a “pancake” bush for the lower arm rear, mounted through the bush from underneath. It was basically made for a front-wheel-drive vehicle, but we looked at it and said we need to go back to first principals. If you look at the compliance, the movement of the lower arm, we said that we need to make it into a roll-cage shape. It’s a matter of looking at the ideal and working out the simplest way to get at it, and this is the basis of all these different changes.”
Power assistance for the steering is now a completely electrical system, whereas it was previously hydraulic: “You can see that the power assistance motor is mounted on the rack,” continued Yamamoto. “But if you have a look at all the other vehicles in the Mazda lineup, and probably others' as well, it’s more common to fit the motor on the steering column. You have to have precise feedback in a sports car, and for us to achieve that the motor has to be on the rack.”
The cabin has been moved slightly further back, and the hip points of the seats have been lowered, reflecting the lower center of gravity of the new car.Continue reading »