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).
Stiffness of frames and bodies with folding tops, comparing different constructions and suspension systems.
| Identifier | ExFiles\Box 117\1\ scan0313 | |
| Date | 10th February 1939 | |
| 1021 W/S. (CT). c. Sg.{Arthur F. Sidgreaves - MD} c. Hs.{Lord Ernest Hives - Chair} c. Rm.{William Robotham - Chief Engineer} c. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} BY.10/C.21.2.39. BODIES WITH FOLDING TOPS. C.7/C.10.2.39. It is evident that the coachbuilders referred to have been primed by Lagondas, but the suggestion re stiff top bodies is not correct for the following reasons :- (a). No frame, however stiff, is at all comparable with the same frame plus a body bolted to same. The difference in stiffness is that 'body-plus-frame' is five to six times the stiffness of the frame by itself. (b). Since (a) is simply a statement of fact based on measuring the stiffness of the frames of a number of well known modern types of car, it is clear that, whether one desires to do so or not, fixed top bodies carry most of the stress on any modern car. (c). That the above facts do not mean that the body suffers is certain, as we have evidence from Phan. 1, Phan.ll, Phan.lll, 20/25 and 25/30, to Bentley, all with frames of very different stiffnesses, all of which gave good service. The Bentley in particular had an extremely flexible frame - my own car with an 8 1/2 cwt. body of wood and aluminium construction has run 3 1/2 years, and the body is still quite free from squeaks and rattles. I am dealing in above with facts not untried theories. With regard now to the question of folding-tops relative to frame stiffness, it may be that the Lagonda frame and its method of suspension enables this type of body to be used without a stabiliser or extra bottom side stiffness, but in any case it has other very serious disabilities due to the torsion rod type of front suspension, and if our competitors are using propaganda of above type we must not be 'scared off' by fear of Mr. Good from stating that although this form of suspension relieves the side member of torsion in the part of the side member which projects beyond the end of the scuttle it does so at the expense of bringing road reactions as roughnesses into the body itself. We actually built a car with torsion rod suspension, just like Lagonda's scheme, but abandoned it in favour of our present designs, as we could not keep road | ||