The Autumn issue of the Bulletin of the Vintage Sports Car Club UK has a great article on the 1907 Grand Prix Christie. The article contains 8 pages of high quality photos and history of this famous Christie racer. I worked with John Staveley and the editors to produce a sketch of what the transmission may have looked like on the car. This is the first known attempt to imagine what Christie was thinking, since no photos or drawings exist. I believe Walter Christie realized that his previously exposed transmission gears were not such a good idea. So the biggest change he made from the 1906 racer was to enclose the transmission gears inside the left end of the crankcase. The concept included some features from his patent; a long transverse shaft still had to drive each front wheel through each outboard clutch housing. Otherwise the 1907 engine used a similar V4 configuration and the same cylinders as the 1906 car. The 1907 racer wasn't really much faster, period articles claim the bore and stroke were actually reduced by 1/8inch. But Christie really needed a new car, as the 1906 chassis had been raced continuously since early 1905. Below is a small image of the proposed transmission layout. Contact me for a copy of the article.
The 1907 Christie racer was a completely new design by Walter Christie. No parts were used from his previous racer. He had his sights set on the 1907 French Grand Prix. Christie patented his front drive system in France as well as USA and he may have thought a race would be a good promotion opportunity. After poor showings in 2 Vanderbilt Cup events, it is amazing that Christie felt he could take on the best European racers. However, Christie did a lot of private testing before the race, and he claimed to have reached speeds of 120mph. Unfortunately he had engine and/or clutch problems in the race and dropped out on lap 4.
This GP Christie had a bore & stroke of 7 1/4" each. Christie still used 8 atmospheric inlet valves per cylinder but he did move the mechanically opened exhaust valve to an overhead position. The car was claimed to weigh under 1800lbs when most of his competitors were at the 2200lb limit.
Lee Stohr (b.1957: Delaware, USA) is an American race car designer and owner of STOHR DESIGN