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).
Engine oil specifications, potential causes for wristpin bushing issues, and the quality and future of brake systems.
| Identifier | ExFiles\Box 170\2\ img245 | |
| Date | 12th January 1935 guessed | |
| -7- It is about SAE 60 or 110 seconds at 210 degrees Fahrenheit. 90 second oils are recommended for the transmission in winter time. So you have been running on an oil heavier than transmission oil. Normal summer engine oil is SAE 40 and this would be used for severe testing even in winter. SAE 50 is rarely used under the heaviest driving conditions in the hottest weather. This might account for gumming up but not for the etching which we observe on the wristpin bushing. We think the etching must mean that the crank-case ventilator is stopped up, either at the intake filter A (sketch) or at the outlets B or else the outlets have been damaged and do not poke down into the slip stream under the car as they should. Gilbert says he knows of only one other case of this happening on a 16 and that was Thompson's brother in Portland, Oregon, who used some fancy oil with gum or creosote in it. Actually trouble with tappets and wristpins is almost unknown on the sixteen. In summer weather of say 100 degrees we should expect big end trouble on a car driven consistently near the limit, but no trouble with wristpins. I agree with you that the strip bearings look rather pathetic at first, but their service record is particularly clean since they have been heat-treated. We shipped replacement bushings and pins to you on December 20. No charge. Brakes We have no comeback on these. They are not good. If the sixteen were of any importance to us we should be moving heaven and earth to improve them. As it is, with the "high price class" starting this year at $1250.00, we cannot afford to grow pale sitting up nights with a car which represents one hundredth of one percent of the yearly output of the American cars. Entirely wrong attitude I know - but who pays our wages? We are only really interested in hydraulic brakes and it looks as though in a year these would be pretty nearly standard throughout the industry. Cast iron drums are giving way to centrifuges drums, which have a higher modulus of elasticity and therefore avoid "fading". Eighty carbon | ||