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).
Test drive report on the experimental car 12-EX, detailing steering, engine, and vibration issues.
| Identifier | WestWitteringFiles\P\July1926-September1926\ Scan039 | |
| Date | 22th July 1926 | |
| R.R. 235A (100 T) (S.H. 159. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} Copy to - BI. (struck through) " WOR.{Arthur Wormald - General Works Manager} (struck through) " RY. (struck through) ORIGINAL 12-EX. X7940 (struck through) X7430 (struck through) X6325 (struck through) X7685 (struck through) I drove 12-EX. to London, and thought, while the steering was extremely light and easy, it may be found to be a little too free, and therefore rather susceptible to out of balance wheels etc. I was however extremely pleased with the steering with this exception. Regarding the automatic advance, this too is a great improvement in the direction of reducing detonations, and making the engine pick up smoothly. It would be an excellent test to get a similar set fitted to 10-EX. (blue, high compression car.) The point about this item is that both the battery and magneto should have their drives advanced because it was impossible with the hand control to get too much advance suitable for rather weak mixtures, and moreover the average driver would be running with too late an ignition, losing power, and very bad for petrol consumption. I do not know how much advance is needed but it appeared to require a little more on the magneto than on the battery. I suggest perfect synchronism at about 10° earlier on the crankshaft. I thought however the carburetter was set a little too strong, which may have been the cause of the apparent lateness of the ignition, and loss of power unless absolutely fully advanced at slow speed. We noticed on this car that the serrated rollers on the back springs had not been altered to the 90° type. It does not seem much use testing the acme type of roller unless it is thought this is better than the 90°. You will remember that the petrol gauge is still wrong, with incorrect washers, and the screw fixing on the hand is too high. Regarding the engine vibration I thought these could be felt on the steering wheel more than usual, possibly due to the more rigid fixing of the steering column, which now appears to be very satisfactory as regards foot clearance. I do not know if it is the engine that is slightly out of balance, but I fear it may arise from the extra weight of the pistons. It is especially noticeable somewhere in the neighbourhood of 40 MPH. We shall be very anxious to test at the first possible moment some lighter pistons made from magnesium castings. R.{Sir Henry Royce} | ||