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).
Vehicle's recurring exhaust manifold failure, a new axle's performance, and engine roughness at high speed.
| Identifier | ExFiles\Box 5a\2\ 02-page211 | |
| Date | 14th March 1930 | |
| To: Hs{Lord Ernest Hives - Chair}/Bm. From G.E.H. Hôtel de France, Châteauroux. NEW EXHAUST MANIFOLD PRESENT ONE HOPELESS. This has failed twice during the last two days. In the first instance, at the joint to the downtake pipe, the manifold breaking right across one lug. After we had had this welded, the manifold again broke at the previous welding. Before dismantling the manifold, it was found that there was almost a space of 1/16" at the gap where the breakage occurred. This means that the exhaust manifold was too short and had again contracted. We wish we could enforce upon you the heat these manifolds get to during these runs. It was noticed the other night when running in the dark that the manifold was almost white hot. It is equal to any dynamometer test that is taken. We also find that the thickness of the pipe is very uneven, one side not being much more than .125" thick, whilst the other side is .312" thick. This of course is a weakness and should be attended to. (With regard to your Hs{Lord Ernest Hives - Chair}/Ret/ld.14/3/30, we are very pleased to see your statements in regard to the slope of the shock absorber arm. If you will spare one moment and look up our report sent to you on 1/7/29, you will see that we were of the opinion then that the failure was in all probability due to the slope upwards of the shock absorber arm in normal positions, and worse in abnormal positions. We gave you a report yesterday of another theory which up to now seems to be more or less correct, as the ball pads have not since run dry, but we will verify the amount of oil that flows out of the ball end with one depression of the oiler). We have received your telegram to-day:- EXHAUST MANIFOLD DESPATCHED YESTERDAY. ROBSON. Re the new axle sent out. This axle has got the same overrun period as the old one. It is not so easy to discern this period when sitting in the driving seat, but it can be distinctly heard and felt when sitting in the rear seat. There is also a slight definite slack in the pinion housing of the new axle laterally. The amount of back lash is considerably less than the old axle. We shall watch this bearing very carefully, because we do not think that it will last very long in its present condition. The overrun period that we have previously mentioned is one that the Test Dept. would very quickly pick up and condemn the axle for. The other parts of the car, particularly the engine is running beautifully sweet and smooth. It is a pity that the engine becomes rough over 60 M.P.H., because dead on 60 one hardly realizes the engine is running, but immediately you get to 60.5 or 61 M.P.H. you start to feel the rough period. G.E.H. | ||