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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 tests.

Identifier  ExFiles\Box 11\4\  04-page130
Date  30th June 1929 guessed
  
_5_

E.79094 Expansion Box made with 9 SWG. S/M.{Mr Moon / Mr Moore}
E.82574. E.83021. Intermediate Pipes,
made with 13 SWG. S/M.{Mr Moon / Mr Moore}
Downtake Pipe made straight, deleting present
bend in pipe, 9 SWG. S/M.{Mr Moon / Mr Moore}
2, 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
valves has taken place.

The tinniness 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/SLV 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 has opened out somewhat, proving
that there is still too much back pressure at the snout.

SYNCHRONMESH GEARBOX to LOP.G.79951.

The following New Parts fitted to avoid
3rd gear coming out of mesh -
G.80052 Shaft, G.80065 Sleeve, G.80076 Lever,
G.80079/80 Levers, G.80082 Pin, G.80078 Rocking Shaft,
G.80081 Stirrup.

Gearbox filled with 7 pints of Engine Oil (Motorine O.{Mr Oldham})

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
  
  


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