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).
Series of tests conducted to diagnose and resolve a high-speed wobble complaint on car 137 X.J.
| Identifier | ExFiles\Box 47\2\ Scan416 | |
| Date | 28th November 1930 | |
| To Rm{William Robotham - Chief Engineer}, File. X4117. REPORT ON 137 X.J. & 91 G.Y. AT CRICKLEWOOD, LONDON. 28-11-30 To 3-12-30. 137 X.J. OWNER:- The Hon. CHARLES WINN. COMPLAINT:- CYCLONIC HIGH SPEED WOBBLE. 1ST TEST: CONDITION OF CAR. ROAD SPRINGS:- 1200 - 1250 LBS REPLACING 1100-1150 LBS. WHEELS & TYRES:- DUNLOP 7"x 21" BALANCED AT 35 LBS/SQ". FRONT DAMPERS:- BOTH CHECKED AT 100 LBS & 70 LBS. CROSS STEERING TUBE:- LOAD OF 18 LBS. SIDE STEERING TUBE:- REAR END .100" EXTRA SET-UP. PIVOT LEAN:- 2° BACKWARD. TRACK:- 1/8" TOE-IN. BOTH PIVOTS:- .035" & .045" END PLAY. RESULT:- NO HIGH SPEED WOBBLE OBTAINED. WET ROADS. BAD JOGGLE PERIODS ABOVE 70 MPH. WOULD DEVELOP LIGHT WOBBLE GIVEN WORSE ROAD CONDITIONS. FRONT AXLE TOO LIVELY. NOT SUFFICIENT DAMPING. SELF - CENTERING 50%. ON THE BORDER LINE FOR HEAVYNESS. 2ND TEST:- CONDITIONS AS BEFORE. ALTERATIONS:- FRONT DAMPERS RESET TO 100 LBS. EACH WAY. END PLAY OF PIVOTS REDUCED TO .015". RESULT:- NO HIGH SPEED WOBBLE. NO JOGGLE PERIODS. SLIGHT JOGGLE OCCASIONALLY. SELF - CENTERING IMPROVED. DIRECTIONAL IMPROVED. STEERING AS NEAR PERFECT AS POSSIBLE. 3RD TEST:- CONDITIONS AS 2ND TEST. ALTERATION:- FRONT DAMPERS RESET TO 80 & 70 LBS. RESULT:- NO HIGH SPEED WOBBLE. DRY ROADS. BAD JOGGLES AGAIN ABOVE 70 MPH., 25% LESS THAN TEST 1. | ||