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).
Overdrive tests conducted at Brooklands race track.
| Identifier | ExFiles\Box 94\2\ scan0195 | |
| Date | 25th March 1937 | |
| x328 To Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} 25th March, 1937. 36-EX Overdrive Tests - Brooklands. Normal top gear. at 3500 R.P.M./73 M.P.H. final oil temp, 95° after 25 laps/72 miles. Overdrive. was then engaged and same road speed (74 M.P.H. on speedometer) maintained with temp., rising steadily to 106°C. after 6 laps/17 miles. During the next two laps temp. suddenly rose to maximum of 132°C. as if temporary seizure occured. The next and following laps shewed a steady decline until after a total of 25 laps the temp. was fairly constant at 112°C. Oil pressure 28 lbs/sq.in. water 95°C. Overdrive at 3250 R.P.M./85 M.P.H. corrected; speedometer reading 90 M.P.H. 6.7% fast. Temperature gradually rose from 70°C on the first lap to 124/6°C. during the last 5 laps covering 25 laps or total of 72 miles. This test was carried out in rain as on opportunity to keep the tyres cool on a wet track. Oil pressure 30 lbs/sq.in. water 90°C. Sparking Plugs. K.L.G.E.26. These ran a total of 741 miles. During the overdrive tests these were O.K. on both banks during 100 laps at speeds 74/85 M.P.H. 4000 R.P.M. maximum. The engine would not run slow after 25, 50 or 100 laps consistently and misfied on acceleration. This was no doubt due to the valves not sealing properly as the oil pressure dropped to 2/3 lbs.sq.in. at very low speeds. Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe} | ||