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).
Exhaust system modifications and synchromesh gearbox performance.
| Identifier | Morton\M18\ img057 | |
| Date | 30th June 1929 guessed | |
| -3- E.79094 Expansion Box made with 9 S.W.G. 1/- E.82071. Intermediate Pipe, with 13 S.W.G. 3/- Downtake pipe made straight, deleting present bend in pipe, 9 S.W.G. 3/- E.82567 Bolts S/SLV, fitted to rear of manifold joint to downtake pipe. No lagging fitted to any part. There has been no exhaust booms, the overrun being particularly quiet. The free exhaust has probably helped to keep the valves cooler, as no stretching of the exhaust valves has taken place. The timiness of the exhaust is approx. 20% more than a standard lagged exhaust system with the engine idling. The exhaust beat is the most objectionable feature. The noise at the snout is approx. 10% more. The values are taken in comparison with 60 JS.{Mr Johnson's Secretary} "There has been no sticking of the sliding joint." The stiffer intermediate pipe does not so easily distort, which is the cause of the sliding joint sticking. The two E.82567 bolts made in S/NV were fitted as an experiment to prevent stretching due to heat, to prevent the blowing of the exhaust joint between the manifold and the downpipe. Up to the present mileage there has been no exhaust blow from this joint. The exhaust snout had opened out somewhat, proving that there is still too much back pressure at the snout. SYNCHROMESH GEARBOX to LOR.G.79951. The following New Parts fitted to avoid 3rd gear coming out of mesh - G.80054 Shaft, G.80065 Sleeve, G.80076 Lever, G.80078/80 Levers, G.80082 Pin, G.80078 Rocking Shaft, G.80089 Stirrup. Gearbox filled with 7 pints of Engine Oil (Motorine C.) The synchromesh gear changing is very good if time is allowed in changing. The orthodox method of quick change cannot be carried out from 2nd to 3rd, or top to 3rd, without first feeling a temporary obstruction. A very quick and perfectly quiet change can be made with these gears, by the usual method of double clutching. On the other hand, if a quick change is made without double clutching, the gears are crashed. The revolving mass of the synchromesh with the present leverage of the change speed mechanism defeats the quick change. If the leverage could be reduced, we are of the opinion that the crashing of the gears in quick changes would be reduced. Our object in reporting upon the double | ||