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).
Technical letter advising on how to increase shock absorber loads for car 18-EX by drilling valves and varying washers.
| Identifier | ExFiles\Box 19\5\ Scan147 | |
| Date | 12th February 1931 | |
| F.{Mr Friese} Dodd, Restaurant Octobon, Le CanadelHenry Royce's French residence, Par-Le-Lavandou, (Var) France. x899~ From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}3/KT.12.2.31. We note that you wish to raise the shock absorber loads on 18-EX. We send you herewith a chart showing the way the loads can be varied by varying the washers under the valve caps. We are almost certain that these loads were brought up to the chart before it left Derby. The loads on the front shock absorbers are, high pressure 80 lbs, low pressure 70 lbs, rear, high pressure 85 lbs, low pressure 80 lbs. Experiments we have been doing here show that we get the best results from the following loads, front 120 lbs up and down with a .032 hole drilled in the high pressure valve, rear 100 lbs up and 115 lbs down with a .055 hole drilled in the high pressure valve. To obtain these loads you will have to reduce the working length of the valve spring on the front, H.P. .070" L.P. .090" and rear, H.P. .075" L.P. .045" If, as we think, your shock absorbers are arranged according to the chart, you will have no washers under your valve caps at the front and no washers under the high pressure valve cap at the rear, and a .045 washer under the low pressure valve cap at the rear. Since it is undesirable to run without any washers under the valve caps, you can place the small discs we send over the valve spring in the position we mark 'A' in the print and a similar thickness of washer under the valve cap at 'X' (i.e. .050"). The result of drilling the valves is the marked increase in the softness of the riding without destroying the controlability of the car, but we know that R.{Sir Henry Royce} is averse to having the valve drilled, so that you had better alter the loads only at first and leave the valves undrilled. Actually | ||