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).
Tests and modifications to a vehicle's suspension and steering geometry to correct oversteer and other handling issues.
| Identifier | ExFiles\Box 17\4\ Scan098 | |
| Date | 10th December 1934 | |
| -2- HS{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}20/KW.10.12.34. The bottom suspension links were then reduced in length to give parallel motion, the steering geometry being unaltered. No difference was found as regards joggles but the car had become very uncontrollable on fast corners, showing a marked tendency to over steer. Static tests were carried out by rolling the car with the wheels on lock, the results showing that as the car rolls the road wheels "put on rudder" and the steering wheel goes the opposite way, as given in the attached table. Corrected steering geometry for parallel motion was now fitted, to N.Sch.4237. This corrects the geometry in the straight ahead position but still over steers on lock when rolling to a small extent. At the same time we refitted the R.R. steering box. Slight shocks were noticeable at low speeds, but at high speeds joggling was the least so far obtained. The car still had an unpleasant feel on corners, and could not be steered accurately on a fast corner. We conclude from the tests on this car and 27-KX (see separate memo.) that shocks are caused by gyrostatic action inherent in the Cadillac suspension or by frame jellying causing the wheels no longer to have parallel motion inducing gyro forces. We set out to show, and have shown on 27-KX, that a car with parallel motion and perfect steering geometry will not have road shocks if the frame is free from jellying. It remains to show whether we can eliminate the wandering on corners with the parallel motion by a front roll rod, steering geometry that understeers, or by sloping the rear springs to steer outwards when the car rolls. In any case we do not recommend fitting a worm and nut box, as even in the last experiment the steering would have been better with an irreversible box. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||