SAKHIR, Bahrain -- Valtteri Bottas set the pace on the second morning of in-season testing at the Bahrain International Circuit.
The Mercedes driver clocked up an impressive 79 laps at the wheel of the W08, taking over from Lewis Hamilton who drove 97 laps on Tuesday. The car stopped on track at Turn 4 with a mechanical issue on the steering wheel in the early afternoon, causing a red flag, but it was back on track just 15 minutes after returning to the garage.
Esteban Ocon was second fastest in the Force India, with a best time 0.371s off Bottas before handing over to teammate Sergio Perez in the afternoon. Daniil Kvyat is splitting the day in the Toro Rosso with teammate Carlos Sainz and at the midway point of the day had completed 61 laps after working through a series of setup changes in the morning.
After completing 130 laps of tyre testing on Tuesday (that included extending Pirelli and Ferrari's running until 20:00) Sebastian Vettel was back on track and fourth fastest, but completed just 12 laps in the morning due to a planned setup change that uncovered a few minor issues. That led to an extended period of downtime in the garage as the team conducted a series of systems checks, but the car reappeared in the early afternoon.
Gary Paffett returned to an official Formula One test for the first time since 2013 and racked up 59 laps in the Williams during the morning. His best lap was 1.386s off Bottas' fastest time and was enough to sit fifth in the timesheets after four and half hours of testing.
After an ERS water leak and subsequent power unit change cost McLaren-Honda most of its track time on Tuesday, Stoffel Vandoorne returned to the track to complete 49 laps on Wednesday morning. The team said the small amount of running on Tuesday helped shape Wednesday's run plan after Honda went into the week hoping to analyse a number of "new ideas" with its power unit.
Kevin Magnussen was seventh fastest as Haas continued testing brakes from potential new supplier Carbon Industrie. The team has struggled with its Brembo brakes for over a year, although an upgrade at the Chinese Grand Prix from the Italian supplier saw a number of the issues resolved. However, if the team can sync its mapping and brake-by-wire system with the Carbon Industrie brakes, they could be introduced as soon as the Russian Grand Prix next week.
Renault reserve driver Sergey Sirotkin took to the wheel of the RS17 for 44 laps in the morning session and set a time 2.403s off the pace of Bottas. Red Bull junior Pierre Gasly, who is currently racing in Japan's Super Formula, took over with a new power unit after Daniel Ricciardo's session was brought to an early end on Tuesday.
Pascal Wehrlein, who took part in his first grand prix of the season on Sunday after recovering from a pre-season back injury, was at the bottom of the timesheets after 42 laps in the Sauber.
Times at 13:30
1. Valtteri Bottas, Mercedes, 1:31.771, 79 laps
2. Esteban Ocon, Force India, 1:32.142, 60 laps
3. Daniil Kvyat, Toro Rosso, 1:32.615, 61 laps
4. Sebastian Vettel, Ferrari, 1:32.615, 12 laps
5. Gary Paffett, Williams, 1:33.157, 59 laps
6. Stoffel Vandoorne, McLaren, 1:33.190, 49 laps
7. Kevin Magnussen, Haas, 1:33.192, 37 laps
8. Sergey Sirotkin, Renault, 1:34.174, 44 laps
9. Pierre Gasly, Red Bull, 1:34.407, 51 laps
10. Pascal Wehrlein, Sauber, 1:35.212, 42 laps