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).
Brake thumping and carburation performance of a 25HP car following a 700-mile drive.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan246 | |
| Date | 20th August 1930 | |
| HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce} BY.{R.W. Bailey - Chief Engineer} ) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} [Stamp: RECEIVED 22 AUG 1930 HS{Lord Ernest Hives - Chair}] 25HP. CAR (JAPAN). R1/M20.8.30. x5770 x5080 x5000 BRAKES. During the holidays I drove the 25HP. car (Japan) about 700 miles. In that time the most obvious fault appeared to be the thumping of the brakes when suddenly applied. Naturally I thought the adjustment was good as the car has not done a great mileage since it left the Works. In studying the matter with Messrs Day and Hardy it was suggested however that the thud was a service development which led to the closer adjustment of the 4 wheel brakes. Now, as the pedal does not indicate the condition and necessity for adjustment of the front brakes it seems better that the thud should not be cured if it is an indication that the brakes on the front axle should be re-adjusted, and this is the conclusion I have come to as the thud cannot be now obtained since the closer adjustment has been made. Will HS.{Lord Ernest Hives - Chair} kindly confirm this and see how it stands in our instruction book. CARBURATION. After the journey into Lincolnshire I concluded that the high speed jet was relatively too strong so I made careful examination of the carburetter and after re-adjusting and carefully marking it and shortening the air valve spring slightly, I could find no fault with the action of the carburetter either instantaneously or after giving it time to settle down. The consumption worked out at 18 MPG. at an average speed of 30 MPH. nearly all the way against a fairly strong head wind. This I consider very satisfactory considering the piston displacement per ton mile, and the high engine speed relative to the car, thatis, we do not expect good petrol consumption with these cars of great acceleration. The distribution hot and cold was extremely satisfactory, and though I am not entirely satisfied with the exhaust system as regards silence it had the great virtue of not firing in the exhaust either with the cutout open or closed. (1) | ||