The company’s head of vehicle evaluation, David Coleman, told the Australian media at the car’s launch in California that the inclusion of an electric power steering system in the new Mazda 3 was a great opportunity but one which the company knew had plenty of risks.
“With electric power steering there’s really an opportunity to make this thing feel really good, there’s also a danger of making it feel really awful” Coleman said, pointing out that some competitors in the segment had fallen into the second category.
Coleman admitted that for the previous generation Mazda 3 the company benchmarked BMWs but that this time around it looked more inside its own range of cars, particularly at the MX-5. The car which was the ideal goal for enthusiasts was set as an MX-5 with manual steering, from which point the steering engineers could work backwards towards a good compromise.
“When I am tuning electric steering I must have this vision [of manual steering in the MX-5] in my head.”
For the previous Mazda 3, which made use of hydraulic steering, there was plenty of initial weight around centre that allowed for good self-centering but that weight build up couldn’t be maintained around corners, as it would get far too heavy.
This time around the engineers focused on providing the same linear build up of steering weight as found in a manual steering system, to improve feel and response. The tuning was carried out by Mazda’s American engineers around the winding roads of south California, where – despite common belief – it’s filled with corners and twisty roads.
However the steering tune wasn’t limited just to the software and mapping, it went far deeper, to a mechanical level.
“We couldn’t have thrown the same effort rate at the old system, [as we] need a very stable suspension system.”
The new Mazda 3’s rear suspension has been set up to provide a natural toe-in response, a form of passive rear steering, which helps stabilise the car at high speed. But the big change has been to the caster angle for the front suspension.
The caster angle is the steering axis lean-back, which is the angle of the tyre pushing back against the car. Previously this has been set at three degrees, which is typical of a front-wheel drive car; but the new Mazda 3 has it set at 6.5 degrees, the same as the Mazda RX-8 and MX-5.
“We intentionally built this to put more force into the steering, so we had something to fight against with power assist. Power assist can’t make the steering heavier it can only make it lighter. So to make it heavier mechanically and then making it lighter with power assist we were able to have the force required to generate steering feel.”
Our drive of the new Mazda 3 confirmed that it has class-leading steering feedback and response. However, it remains to be seen how the American tune will handle Australian roads.
The 2014 Mazda 3 launches in Australian in late January 2014. In the interim read: Mazda 3 Review.