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).
Improvements and required modifications for a prototype vehicle based on road testing.
| Identifier | ExFiles\Box 17\3\ Scan020 | |
| Date | 26th June 1926 | |
| To Hs.{Lord Ernest Hives - Chair} & BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to PN.{Mr Northey} CWB. X7430 R2/M26.6.26. 12-EX X.7940 X.7430 X.7770 X.7410 This is a fine car in many ways than previously. One can feel the definite improvement in the steering - i.e. easy and free from road shocks, easier to shunt, due to new axle and lighter buffer springs. The stiffer steering column gives slightly more feeling of engine etc. Improved riding seemed manifest, almost certainly due to RR. hydraulic dampers at front and rear. I am definitely of the opinion that these should be double acting, not less than 50% of rebound check - i.e. 80/40 to 100/50. I was surprised to see many pieces still on the engine. Regarding the gunmetal carburetter we thought alum. had been standardised. E.{Mr Elliott - Chief Engineer} will instruct a few more pieces in lighter metal. I stopped this car from going to France because of the weak point in the axle, mostly WW. fault, but still further weakened by Derby's square corners and undecided section. While the car is in Derby we should correct all the defective features on the axle, and add a few more lightened and improved parts: some are simpler. The change speed is not altogether satisfactory; sliding sideways it sometimes sticks. The remedy is lighter centralising spring (half stiffness), hardened shaft and bushes. Let a sharp mechanic see if he can detect any unusual binding. Position plungers should be drilled for hydraulic relief, and groove made two thirds the present depth and width. The engine was very smooth and free from detonations at low speeds, due to correct and efficient working of the auto: advance. Perhaps this engine would be smoother at high speed if the auto. advance was less active - i.e. we may have gained very much at slow speed, and lost a little smoothness at high speed, but it is quite easy to remedy this over efficient feature. The staybright silencer seem rusty. The cutout appeared better for the stop. The back tank was fine; next feature is larger gauge. Autovac parts are unnecessarily heavy; why not fitted with better slow running device. Vee plates and rollers on back springs looked good but I understood the Vees should be say 90°, but you appear to have fitted acme; which type is correct? Amarica will have had experience. There appeared to be some errors in Dunlop wheels: should be more clearance between spokes and brake drums (front wheels). I found on 7-EX a reason for a means of oiling starter relay toggle. Get this applied to 12-EX. (Continued when time permits). (R.{Sir Henry Royce}) | ||