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).
Troubles and investigations into rear wheel arch clearance, comparing the W.J. series and Phantom chassis.
| Identifier | ExFiles\Box 14\8\ Scan164 | |
| Date | 5th September 1929 | |
| By.{R.W. Bailey - Chief Engineer} } FROM De/EV.{Ivan Evernden - coachwork} HS.{Lord Ernest Hives - Chair} } C. CX.{Major Len W. Cox - Advertising Manager} HO. C. JG. GY/MNG. SECRET. X7380 Da{Bernard Day - Chassis Design}/Bv1/M5.9.29. X. 7380 X. 7380. REAR WHEEL ARCH CLEARANCE. We have reported to you in another memo some troubles we have experienced with the new SS.{S. Smith} cars at the coachbuilders in connection with the rear wheel arch, and our recommended immediate actions. We have investigated the matter geometrically, and illustrate our investigations on N. sch. 2938 herewith. On the uppermost section we show the W.J. series rear axle first in black pencil rocked up about the centre of the stationary wheel, secondly about the centre of the road spring (in blue), and thirdly rocked up about an axis on the centreline of the car at the level of the top leaf of the road springs under full load, this is point B, and shows the brake drum shield fouling the wheel arch at about the point it does when we apply the rolling test. The lower half shows a section of the Phantom. In pencil we show the single wheel bump, the axle being rocked about the centre of the other wheel, and in black ink we show the effect of rocking the axle about a point on the centreline of the car level with the bottom leaf of the spring under full load. We have reason to believe from these conditions that whereas the rolling of the body on the springs with full load equipment on the Phantom gave a test of the rear wheel arch that was satisfactory, when a similar test is applied to the W.J. series chassis the results are very erroneous. When the mass of the body, which is suspended on two elastic springs, is rolled it will oscillate about its centre of suspension, that will be a point on the centre-line of the car at the level of the main leaf of the rear spring. This is point B. on W.J. series, point C. on Phantom. Since W.J. series has a spring which is under the axle, and Phantom a spring over the axle, B. is much nearer the road than C. therefore the body translates much more. It will be seen from the indications in a broken line in pencil that if a wheel arch were made on W.J. series to cater for a similar roll about point B. to that which the Phantom wheel arch now almost will permit of about point C. the actual width between the wheel arches would have to be reduced by inches. | ||