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).
Letter from the Experimental Department to Cadillac Motor Car Co. discussing Delco shock absorbers and steering wobble.
| Identifier | ExFiles\Box 170\2\ img008 | |
| Date | 21th February 1931 | |
| Hs.{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/MJ. Expl. Dept. February 21st.1931. M.O.ley Esq., Cadillac Motor Car Co., Detroit, Michigan. Dear Oy., I have read with interest your letter of Feb.11th 1931. With reference to your remarks re. shock absorbers. We do not think that the valves in the Delco Horizontal Shock Absorber are really so small that they give a big pressure velocity rise for this reason. We find that the pressure velocity rise appears to be purposely induced by masking the valve and using a very high rating valve spring on the high pressure side. We think this is a nice way of doing the job and what we are thinking is this - up to an axle velocity of about 1½ ft'sec. the ball pin load must not exceed 100 lbs. if harsh riding is to be avoided. With the drilled valve it is quite easy to get a straight line from O to 1½ ft'sec. pressure rise terminating at 100 lbs. On our standard dampers pressure ceases to rise above this figure but with the masked valves we have been trying we can make it go on to any figure we like. Admittedly over big pot holes this makes the car ride rather hard but on ordinary main roads it gives a reasonably good ride, whilst over level-crossings and humped back bridges the axle control seems good. With reference to your question re "shimmy" we did a lot of tests on out of centre point and found that the more we went out of centre point up to about 3" the more reluctant was the steering to wobble and less were road shocks. However, if the steering could be induced to break into high speed wobble by putting the wheels out of balance the violence of the wobble was if anything, greater than with the standard axle. At the present we are using 1½" out of centre point. The Lancia, of course, are using 4½" on the Lambina. | ||