Russell missed most of second practice on Friday afternoon after a transmission problem developed early in the one-hour session.
But he was already running the gearbox he had been set use in Sunday’s race at the Autodromo Hermanos Rodriguez, after his usual high-mileage ‘practice’ gearbox had developed its own problem during FP1 and had been swapped out.
The problem on Russell’s race gearbox meant he takes a five-place grid penalty for getting a new replacement.
Williams’ head of vehicle performance, Dave Robson, said the problems on the gearboxes were not the same.
“So, we had a couple of unrelated gearbox issues with George [on Friday],” Robson said after qualifying, where Russell finished 13th.
“We aren’t yet sure exactly what the cause was. They’re both slightly different issues. Not much else to say I’m afraid.
“In a way we were fortunate because we fitted the spare, which was actually his race gearbox.
“So at least it failed in FP2 rather than [Saturday or Sunday]. But we’re still looking into exactly what the cause was.”
George Russell, Williams
Photo by: Mark Sutton / Motorsport Images
Robson explained that as Williams normally faces “so few gearbox problems” it felt “fairly comfortable bringing the race boxes as a spare” for every grand prix, with the additional costs of transporting more gearboxes around the world the reason why it makes such a choice.
“There are some spare internal components here, so in effect the gearbox George ran in FP1 has been made up with a new set of parts and is now available as a spare here,” Robson added.
“There’s some extra stuff coming out from the UK to go to Brazil [next weekend].
“But it really is just a case of balancing risk. And on this occasion we would’ve rather had another one with us.
“But weighing everything up, the normal risks with the gearbox, it’s not worth the trade we don’t think.”
Russell will start 16th – ahead of the four drivers that have taken new engines this weekend – with Nicholas Latifi boosted from his 17th-place Q1 exit to start 15th by the various grid penalties.
With overtaking usually tough at the Mexico City track because the slipstream effect is reduced by thin air at high altitude, Robson says Williams is hoping the additional headaches the conditions make for F1 cars’ brakes and engines may result in an attritional race where his drivers can still make progress.
“Overtaking is pretty difficult normally here,” Robson explained.
“But I think equally the ambient conditions and the temperature is supposed to be similar to what we’ve had the last couple of days, which is unseasonably high when you look at the statistics for October-November here in Mexico.
“So, I think there is still some hope or expectation from us that it will be tough race for everyone.
“That the brakes, particularly at the front of the car, will be on the limit. And power units will have a tough time as keeping them cool is tricky as well. The tyres as well can behave a little bit peculiarly – particularly when you into all of that brake and power unit saving.
“So, I think normally, if everyone’s car is in good in health the whole race, sort of side by side racing, I don’t think we’ll see too much of that, not much overtaking.
“But it could become a bit more of a battle of attrition, which we’re hoping for anyway. We’ll wait and see. Particularly towards the end of the race, see if things change.”