The FIA has modified its bodywork tests to ensure a floor mounting system used primarily by Ferrari does not circumvent the regulations, autosport.com can reveal, after McLaren asked the governing body for a clarification over the matter.
The issue of movable floors reached a head at the Australian Grand Prix when McLaren boss Ron Dennis suggested that some rivals had interpreted the rules in a way that his team did not agree with.
Although he did not specifically name Ferrari or mention the area of movable floors - sources subsequently revealed that his team were primarily concerned about a spring device fitted to the front section of the F2007 floor.
Article 3.17.4 of Formula One's technical regulations states that no bodywork, such as the floor, can deflect more than 5mm vertically when exposed to a 500 Newton load upward.
The spring device was allegedly calibrated to have enough resistance to allow the floor to pass this FIA flexibility test when the car was in the garage, but then give way when the car was exposed to higher forces out on the circuit.
This would potentially allow the front of the floor to rise up when the car is at speed, which would improve its aerodynamics and specifically increase straight-line speed.
McLaren became aware of Ferrari's device, believed to be used by BMW Sauber as well, early in the Melbourne weekend. Subsequently, autosport.com has learned that McLaren's engineering director Paddy Lowe wrote to the FIA in Australia, asking if his team could fit a similar system to their car.
In his letter, which also contained a diagram of McLaren's plans, Lowe wrote: "We would like to consider the installation of a mechanism on the front of our floor, consisting of springs and pivots.
"By a suitable arrangement and configuration of the springs (rates and preloads) within this mechanism, we will be able to control the flexibility of the bib so as to meet the requirements of the test specified in Article 3.17.4, but to otherwise allow greater flexibility at higher loads by a non-linear characteristic."
Lowe's letter was clearly aimed at clarifying whether or not the use of such a device was deemed legal if its sole intention was to get around the FIA's flexibility tests.
A week later, FIA technical delegate Charlie Whiting responded to McLaren, and in a letter also distributed to every other team, he clarified the allowed usage of such a device - and revealed that bodywork testing would be altered accordingly.
Whiting wrote: "The test described in Article 3.17.4 is intended to test the flexibility of bodywork in that area, not the resistance of a device fitted for the purpose of allowing the bodywork to move further once the maximum test load is exceeded.
"Quite clearly, any such device would be designed to permit flexibility and is therefore strictly prohibited by Article 3.15 of the Technical Regulations.
"We have no objection to a device in this area which is fitted to prevent the bodywork from moving downwards, provided it is clear that it is not designed to circumvent the test described in Article 3.17.4.
"Therefore, with immediate effect, we will be testing bodywork in the relevant area with any such devices removed."
The move could effectively outlaw Ferrari's system, which would be a welcome boost to McLaren after Ferrari dominated the first round of the championship.
"We are going to improve our car one tenth to two tenths every single race weekend, and that is now the race that is on," Whitmarsh said in Australia.
"If Ferrari respond and they can improve at the same rate or quicker than us, then we will find it tough. If they cannot, we will overhaul them. And that is the challenge.
"They are a strong, competent team and that is why we are in F1 - that is why we enjoy that challenge, that chase, and we will be pushing hard this year."