Motor racing-Mercedes win second successive F1 title

* Mercedes win constructors' title * Team made to wait by stewards (Adds detail) By Alan Baldwin SOCHI, Russia, Oct 11 (Reuters) - The 2015 Formula One constructors' world champions T-shirts were ready and waiting but Mercedes team bosses had left the Russian Grand Prix circuit long before anyone could wear them on Sunday. Nearly two hours after Russian president Vladimir Putin had handed Lewis Hamilton the winner's trophy, stewards finally produced a ruling that allowed Mercedes to celebrate their second successive title. Needing to score three points more than nearest rivals Ferrari, Mercedes had been resigned to putting the celebrations on hold for another two weeks when their pole-sitter Nico Rosberg retired early on. Even with Hamilton providing 25 points with his ninth victory in 15 races, Ferrari had taken 28 thanks to Sebastian Vettel's second place and team mate Kimi Raikkonen's fifth. But Raikkonen was under investigation for a collision that cost fellow-Finn Valtteri Bottas third place for Williams and it was just a question of what kind of a penalty he was given. A drop to eighth place left Ferrari with 22 points -- and the celebrations could begin. "We found out upstairs. It just feels special to be a part of it and to have contributed to a team success," Hamilton told reporters as 'We Are The Champions' blared out from the team garages while mechanics packed up. "It is a great, great, great feeling so I feel very proud," added the Briton. "Tomorrow I am going to see the whole team." Mercedes non-executive chairman Niki Lauda will not be present but he revealed, before the final outcome was known, that he had already pre-recorded an address to the factories in Brackley and Brixworth. "Everything was over-confident that we were going to win it here," he said. "I even had to do a speech this morning for tomorrow because I can't come tomorrow because of another commitment in Berlin." Mercedes motorsport head Toto Wolff had told reporters on Saturday that the victory T-shirts were ready in the hospitality unit. In the end, the preparations were not wasted and Dieter Zetsche, head of Mercedes-Benz and chairman of the board of management of parent company Daimler, was able to express his satisfaction for an 'incredible moment'. "After winning in 2014, we raised the bar again to secure this year's title, and we needed to because our rivals gave us plenty of headaches as they stepped up their performance," he declared. (Editing by Ed Osmond)