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).
Steering tests for car 27-EX, fitted with parallel motion independent front suspension, to diagnose high speed wobble.
| Identifier | ExFiles\Box 17\4\ Scan099 | |
| Date | 10th December 1934 | |
| Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}21/KW.10.12.34. Steering Tests on 27-EX fitted with Parallel Motion Independent Front Suspension. After the steering layout on this car had been altered to give correct geometry, and the front wheels allowed their full movement of 4" either way, we still experienced very bad road shocks whatever the load on the front dampers. At 50 m.p.h. on a bad road the car would high speed wobble. We therefore fitted a bumper bar on extensions to the front of the frame. The bumper was tried with no weights in the ends, with half weights and with whole weights. The effect on the steering was progressively to reduce the speed of maximum jellying and road shocks finally down to 53 m.p.h., the violence of the road shocks being in no way decreased by the bumper bar. We next fitted the dumbell with a hundred pound lead weight each end. Jellying hardly existed except for an occasional joggle on a bad surface. It was always very noticeable during all the tests on this car that the steering was entirely free from joggles except when the car is jellying, when violent shocks appear. The dumbell was now removed and the rear end of the side steering tube, which so far had been solid, was rubber sprung allowing .200 movement either way. The steering was absolutely free from shocks except when cornering. This experiment is in no way a suggested cure, involving sponge in the steering, but was a further demonstration that without a side steering tube a car will not high speed wobble. Snatchometer readings were taken both ways on a stretch of road 3.6 miles long, and to compare these with previous results in Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}3/AD.31.8.31. we have multiplied the results for a run 6 miles each way. | ||