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).
Comparing chassis stiffness, engine mounting, and noise insulation techniques with American car manufacturers.
| Identifier | ExFiles\Box 173\4\ img198 | |
| Date | 2nd January 1934 | |
| -3- He/Gry.{Shadwell Grylls}10/KS.2.1.34. With the Zephyr type body and chassis construction in both cases very little weight reduction would result, although Briggs argue that when the engine inertia is no longer at the front, the frame need not be so stiff. Cadillac maintain that their diamond rubber mounting instead of two front feet prevents the engine from lowering the frame frequency. For a front engined car W. stoutly maintains that the Cadillac cross is in the right place for maximum stiffness, and that an overall frame stiffness of 3000 lbs/ft/degree is essential for a "soft top" car. A welded frame construction instead of riveting increases the stiffness. As the necessity becomes greater for having the engine further forward, we think it worthy of note that both Briggs and Hudsons have people who do nothing except build clay models of complete cars and finally full sized models, to determine a suitable frontal appearance. Certainly the most important feature in which American cars are better than H.R. products is the unobtrusiveness of the engine. This is not only achieved by a cast-iron crankcase, but more by the amount of noise absorbing and deadening material used in the body. Cadillacs do not hesitate to use 5 layers of material on the dashboard where we use one, and are far more lavish throughout the whole body. Briggs recommend that the mats over the floorboards should be as openwork as possible and have absorbing material underneath. Rubber mats reflect the noise and no absorption takes place. Absorbing material should be used in every available part of the body. The aluminium sheets covering the noise insulation of the dashboard on our cars are detrimental to a quiet car and should be replaced by a material such as carpet that allows noise in the body to pass through it and be absorbed in the material behind. The flexible flywheel seems very promising for removing the periods other than torsional in the engine. Three periods in the standard Cadillac V-8 noticeable when the engine is run up light and to a lesser extent on the road, vanish when the flywheel is flexibly mounted. We shall shortly try a similar scheme on Th.III. | ||