From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Engine starting, flywheel gear reduction, and competitor analysis from Chevrolet, Buick, and Cadillac.
| Identifier | ExFiles\Box 173\2\ img187 | |
| Date | 22th February 1934 guessed | |
| IV The engine man has to keep his over-lap down to ensure the start is not prejudiced. The Buick fulfils all these conditions, starts as well as any car so that the timing may be considered O.K. also the choking & manifold. I then found that they were getting 15-1 reduction on the Chevrolet flywheel & that it was done by reducing the tooth size. Thought it sufficiently important to cable you. This has been on Buicks & Chryslers for two years & seems to be the real secret on the job. I had no information of our tooth dimension so dont know how much we can get out of it. The pinion is 8 toothed, 1⅛" overall dia, pitch dia only .015 smaller than the O.D. 1° practically no addendum, flywheel tooth to suit. Pinion made of Nickel Molybdenum S.A.E. 46 15 specification. When they want a lower gear than 15-1, as on the Cadillac, they put all the reduction in the motor and leave the old tooth size on the flywheel for strength. I send you a curve of the Chevrolet starter motor performance with ours sketched in | ||