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).
Urgent need for information on speedometer settings and accuracy issues.
| Identifier | ExFiles\Box 59\2\ Scan004 | |
| Date | 28th January 1930 | |
| For...from PN.{Mr Northey} Copy to R.{Sir Henry Royce} Hs.{Lord Ernest Hives - Chair} H.{Arthur M. Hanbury - Head Complaints} Ref. H.11/CD.28.1.30. PH.3TT28.1.30. It is urgent that we should have information as to the exact position in respect of speedometer settings. The basic consideration has of course been that where these instruments in the past have been inclined to be inaccurate and vary in load, we were anxious that our cars should not be handicapped by their performance being made to look lower than would be justified. It was therefore I believe understood some little time back that we should endeavour to fit speedometers to our chassis which give a 5% optimum reading as a maximum. This would tend to prevent speedometers being fitted which read too low. It is obvious that whatever trouble there might be in obtaining a variable speed instrument, that shall remain reasonably accurate, there should be no doubt about the mileage indicating part of the instrument being almost exact, as many points arising out of a consideration of the cost of running depend upon this factor feature. We have recently had complaints or criticisms from certain owners who allege that their cars, whilst giving a most encouraging performance, judging by the speedometer, have also shown that the well-known distance between two points probably frequently driven by the writers, has been shown to be greater than in fact it should be. We have not had any communications with the A.T. Co. in this matter, and I am not aware that our policy in this respect is known to them, but there are rumours flying around that the gear ratio in our box has been modified to suit the conditions referred to above, and I should be glad to have a very clear statement as to the present position. Is it the case that provided, with a given set of tyres and gear ratio of axles and speedometer, the mileage run by the car is correct, the speed indicating part of the instrument can be variably | ||