Williams says it has not been able to verify Robert Kubica's assertion that his FW42 chassis performs differently from the car supplied to team mate George Russell.
Since the start of the season, Kubica has been outpaced by Russell in almost every session and on race day, the Pole claiming his performance has been undermined by an aerodynamic divergence between his FW42 and Russell's mount.
"It's clear that we are driving two different cars with the same set-up, so that is something we need to understand," Kubica said earlier this season.
Williams investigated the issue but could not confirm its driver's impression.
"I know Robert has thought that the floors were slightly different - we haven't been able to clearly demonstrate through scans that we've done that they are," said deputy team principal Claire Williams.
"But clearly if a driver is telling you that he believes one is different to the other, we've got to get to the bottom of that, which we're trying to do at the moment.
"But then, the feeling that Robert had around that floor, [it] was the floor that was on George's car during the Baku manhole cover incident anyway, so that's effectively gone.
"The chassis, as far as we're concerned, themselves, they're identical chassis."
While the aero analysis of Kubica's car continues, Claire Williams revealed that the British outfit had addressed a braking issue impacting its FW42.
"We have a particular issue with our brake system that we believe we found a solution to, but again, we've got to wait until we run that solution tomorrow, and then we'll understand whether we've resolved that problem," she said.
"If we can fix that, and then some of the other mechanical issues that we're looking at at the moment, then we'll be in better shape.
"But clearly the aero programme to deliver performance from an aero perspective is ongoing."
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