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).
Test report on the effects of soft front springs on vehicle ride and steering wobble.
| Identifier | ExFiles\Box 43\2\ Scan116 | |
| Date | 20th April 1926 | |
| Oy1-E-42026 -3- April 20, 1926 J/S Test II. A pair of very soft front springs were made up. These have nothing but 3/16" plates below the main plate and an initial camber of 4-1/2" to 4-5/8". When clipped to wide pad they show following: #1 Load flat 1070# Stiffness 282 lbs./in. #2 Load flat 1110# Stiffness 284 lbs./in. This corresponds to 4-1/4" spring deflection with 4 passengers in the car, or 5-1/4" total deflection with 6-3/4" tires. The springs of test I by comparison had a stiffness when clipped corresponding to 3-1/2" spring deflection, or 4-1/2" total with 6-3/4" tires. (The tire deflects 1"). With these springs the riding was improved we think (from a short test), but the joggle was still present, and the riding was not improved in a proportion which justified the great risk of spring breakage and braking trouble which would be likely to arise as a result of using such extreme springs. The most interesting point is that whereas England has warned us that with softer front springs high speed wobble would get worse and occur at a lower speed, we have found on the contrary that as we continually soften the front springing, so the steering has improved and the tendency to wobble decreased. With the springs of Test I and vertical shackles we have actually had the car up to 65 m.p.h. several times with 6-3/4" tires at 30-35 lbs. inflation. Though the steering is still snatchy (wheels are unbalanced) we have had no wobble such as we used to have continually with the car as received. Test III. To clear up a doubt as to the effect of shackling the spring in front, Mr. Knapton devised a way of shackling the spring at the rear, which gives a great pivot-lean but is otherwise like a present standard car. | ||