Williams will not 'risk' Formula 1 wheelnut fix in Abu Dhabi GP

Pitstop delays have proved costly on occasion for Williams this season, due to design issues with the wheelnut system rather than problems with crew performance.

Bottas said changes had now been made ready for 2016, but as the fix was unproven the team preferred not to use in the Yas Marina race.

"We've had issues with the wheelnuts coming off, that's been the main problem," he said.

"The guys have been doing a great job. Always, in pitstop practice, they are doing really good, confident pitstops compared to all the top teams.

"But then in the races we've had issues and the wheelnuts don't come off like they should.

"We have found some solutions, which we unfortunately can't race here yet because we don't want to risk anything, it's quite a sensitive part of the car, but I'm confident we can fix those things for next year."

Heading into the final round of the season, Bottas has a one point lead over fellow Finn Kimi Raikkonen for fourth in the drivers' championship.

He acknowledged it would be satisfying if Williams could break the Mercedes/Ferrari monopoly at the head of the standings.

"I think the main thing would be for us as a team to be at least ahead of one quicker car in the championship," Bottas said.

"It doesn't change at all if it is Kimi or someone else who is fighting for that position.

"As I driver, I want to get every position possible.

"With what we have, the car we have and what we are doing as a team, I want to always get the maximum out of it and the maximum ranking in the championship."

Ferrari has generally been faster than Williams in races this season, and Bottas admitted staying ahead of Raikkonen might prove tricky.

"I think it is a not too bad track for us but Ferrari has been very quick on Sundays lately so we need to see if we have enough pace to challenge them," he said.