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).
The inadequacy of rear springs on Bentley chassis due to increasing vehicle weights.
| Identifier | ExFiles\Box 87\4\ scan0070 | |
| Date | 29th April 1935 | |
| [Handwritten: Rm{William Robotham - Chief Engineer}] [Handwritten: +wb{Mr Brazier/Mr Bell}] BY.{R.W. Bailey - Chief Engineer} Hs.{Lord Ernest Hives - Chair} Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister}15/MW29.4.35. ROAD SPRINGS - BENTLEY CHASSIS. ---------------------------- It is our experience that the rear springs fitted to Bentley cars are in many cases too weak. Body weights have steadily increased so that the total weight of the car, instead of being 30 cwts. as originally intended, is now usually between 32 and 33 cwts. There is quite a number as much as 33½ cwts. Obviously, this spoils the performance, and also results in complaints of bumping on the buffers. A further consequence is that with a deflated tyre, the standard jack will not go under the jack pad, see our Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister}17/HR26.4.35. We think that new cars are being passed off with inadequate buffer clearances and we shall ultimately have to fit stronger springs to overcome complaints from the Owners if the cars are used under conditions likely to show up the weakness. An examination of the Reports on Weight of Coachwork for the last series show that the standard laden clearance of 2.600 is rarely obtained. The average clearance appears to be 2.250 to 2.375, but many cars are passed off with 2.000 - some as low as 1.875 - clearance. These clearances are measured with only three passengers and no luggage. Obviously, if some of these cars are taken abroad, and driven fast with four passengers and luggage, the springs are much too weak. We do not think that any cars should be passed off with less than 2.375 clearance. Allowance must be made for the fact that the springs settle down in service quite appreciably; for instance, Chassis B.36-BN{W.O. Bentley / Mr Barrington} was sent out with 2.125 clearance, and after running in Ireland some little time was returned to us with a complaint that the rear springs were too weak. We found on testing the car that the laden clearances were only 1.750" - a reduction of .375" For cars weighing 32 to 33 cwts, we think that the rear spring poundage should be at least 950. Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister} | ||