Williams seek trouble-free Spanish GP

Webber looked set for a decent points haul at the Nurburgring when his car stopped with hydraulic failure - which was his third retirement of the season.

The team hope the modifications, allied to some other changes designed to improve their pace in qualifying and new Bridgestone tyres, will allow them to finally deliver on the potential they have shown so far this season.

Webber said: "I feel we have made some progress in recent tests and I also think Bridgestone is putting some pressure on Michelin, which is good, so I hope we can take some of this progress to the Grand Prix."

And after the double engine change that hit Webber and Rosberg last weekend, Cosworth are confident that the new power-units fitted prior to qualifying are in good shape for their second race.

Simon Corbyn, Head of F1 Race Engineering at Cosworth, said: "We identified no problems with either engine during the post race checks at the Nurburgring."