Mercedes technical director James Allison says the FIA frowned upon Mercedes' initial DAS design which the team had hoped to use during the 2019 season.
The novel Dual Axis Steering, uncovered earlier this year during pre-season testing, allows drivers to tweak the toe angle of a car's front wheels through a push and pull movement of the steering wheel.
The system's benefit resides in the ability to improve straightline speed but also tyre wear.
Mercedes first DAS proposition was submitted to the FIA's scrutiny, but while the latter agreed that the concept was legal, a lever used to actuate the original system sparked the governing body's disapproval and forced Mercedes' engineers back to the drawing board.
"It was really quite difficult indeed," Allison explained in a technical Q&A video released by Mercedes on its YouTube channel.
"In fact, we first wanted to introduce this in 2019. We took our ideas to the FIA, showed them, explained why we thought it was legal and they begrudgingly agreed that dual-axis steering was actually legal.
"But they didn’t much like the way we’d done it because the second axis we were getting from a lever on the wheel rather than that whole-wheel movement.
"So they said ‘no, you’re going to have to move the whole wheel in and out’. And I think when they said that they were hoping that would be too difficult and that we would go away and cause them no more problems."
But Mercedes rose to the challenge, with Allison underscoring the genius of chief designer John Owen. However, while accepted for this year, the FIA has banned the system from 2021.
"Our chief designer John Owen took one look at that challenge and he’s got a really, really good gut feel for whether something is doable or not," explained Allison.
"That’s a really helpful characteristic because it allows us to be quite brave spending money when most people would feel the outcome is quite uncertain.
"But John has a good feel for whether he’s going to be able to get out of the woods and into fair ground again.
"So John took that challenge on, reckoned he could do it, put it out to our very talented group of mechanical designers and between them they cooked up two or three ways in which it might be done.
"We picked the most likely of those three and about a year after that, out popped the DAS system that you saw at the beginning of the season."
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