SILVERSTONE, England (Reuters) - Ferrari's gearboxes have become a weakness that the Formula One team has to fix, Sebastian Vettel said on Saturday after two failures at the British Grand Prix brought him a second successive grid penalty.
The four-times world champion had gearbox problems on Friday and again on Saturday at Silverstone.
"It happened yesterday and today. That's a weakness and we need to stop it," said the German as he contemplated a five-place drop that will leave him starting from 11th spot in Sunday's race.
"I think the other occasions it was more a consequence of things happening. The issue we had yesterday and today is something new and we need to fix it."
Vettel has had a torrid time of late, retiring from the Austrian Grand Prix last weekend after a high-speed tyre blowout while leading.
Tyre supplier Pirelli blamed that on debris on track.
The German said the car was a little off the pace at Silverstone, with Red Bull now looking like the closest challengers to champions Mercedes with Max Verstappen and Daniel Ricciardo on the second row.
"I think we have done good steps in the past but probably not enough, compared to other people, so I think there's a lot of catching up for us to do," said Vettel, who also had a grid penalty in Austria last weekend.
"We need to make the car quicker, to put more downforce in it, make it more efficient at the same time, and add a bit of power."
Ferrari are second overall in the championship but have yet to win a race this season.
Reporting by Alan Baldwin; Editing by Mark Lamport-Stokes