technical data -

Servais Nolos Silencer #4R (2 of)

maintenance -

To be written...

problems -

To be written...

removal -

To be written...

other notes -

Stainless steel (re-manufactured) exhaust systems may be available from P.D.Gough and P.J.Langford.

The strange construction of the silencer is explained in its 1936 patent -

A silencer for gaseous currents, e.g. the exhaust of an internal-combustion engine or the intake of a compressor, of the type comprising a casing provided with a filling of sound-absorbing material so arranged that there is left an unobstructed passage for the gases from the inlet to the outlet, comprises a casing containing a composite filling consisting of a comparatively fine fibrous or like sound-absorbing material, such as steel wool, glass wool, asbestos fibres, ordinary wool, or loose felt, and a more rigid material, such as expanded metal, wire netting, or wire gauze, the rigid material acting as a binding or lacing to hold the fibrous material together. The casing has an inlet, an outlet, and a through passage surrounded by expanded metal and steel wool arranged in alternate layers so as to fill the remaining space in the casing. The filling is made by rolling one end of a length of expanded metal to form a tube, covering the remainder of the length with a layer of steel wool, and rolling up to form a roll adapted to fit in the casing. The fibrous material may be composed of strands of different thicknesses or differing otherwise. According to the Provisional Specification, the filling may consist of a series of annular wads of steel wool or of a corrugated roll of wire gauze.
Presumably Lanchester didn't find it effective enough, since the LD10 uses two silencers.

diagrams -

All images are scanned from originals, wherever possible, at 100dpi (unless otherwise noted) and must be scaled when printed to preserve the original size (eg. scale up by 3 times for a 300dpi printer).

Note, however, that due to slight scaling inaccuracies during both the scanning and inevitably the printing, these images should be taken as an approximation for reference only.
In addition, drawings, measurements and notes of materials used are intended as a guide and aid to the restorer, and not necessarily a definitive, or even guaranteed correct, reference.

The gasket between the inlet / exhaust manifold and the cylinder block.

Measurements for the rear half of the exhaust system.
Note that the silencer box need not be shaped as the original - a simpler rectangular shape will fit and would be cheaper to re-manufacture.
The silencer box is said to be 18" long, 6" wide, 3.3/4" deep with inlet and outlet tubes of 1.5/8" O.D.

Measurements for the front half of the exhaust system.

An alternative exhaust bracket design currently under trial.
The exact drop of the fingers appears to be vehicle specific.
Note that the exhaust bracket is broken or missing from the majority of vehicles - it is located just behind the starter motor.
Note that the (original) bolt cannot be tightened, so requires the use of a "Stiffnut" on it. A "Nylock" nut might work if the heat transfer is very low.

Contrast with this original (broken) bracket shown at 50dpi.

An owner's alternative design for a silencer -
M.S. = Mild Steel
S.S. = Stainless Steel
The design requires:

In this design, the silencer box is divided into three laterally aligned chambers and there are three perforated pipes, which run between the chambers. The two end chambers are only two and a half inches long. The exhaust inlet pipe passes through the end wall of the silencer and through the first cell-dividing bulkhead, where the pipe then connects to a perforated tube. This tube continues through the (13") long, fibreglass filled centre chamber, to the second bulkhead and releases the exhaust gas into the chamber furthest away from the entry point. The second pipe is also perforated and carries the gas back through the central chamber of the box, to the first chamber and releases the gas there. The third perforated pipe again carries the gas down through the central chamber of the silencer box to the bulkhead of the third chamber, where the exit pipe (which is not perforated) takes over. This carries the gas through the end chamber and end wall of the silencer and out towards the back of the car. Each time the gas travels through the large central chamber, it travels through perforated pipes, which allow the escape of any high-pressure pulses. It is this gradual escape, which evens out the pulses and removes the noise. This looks like a very effective design of silencer and might allow the use of only one unit for effective silencing.

(Original) front silencer box (in steel).
The design is simple with just two offset pipes, one of which stops where it reaches the centre of the box and the other stops 1.1/2" short of the centre. Both internal pipes are open-ended perforated tubes with flexible exhaust tubing wrapped around them for the full length. Other than internal supports for the tubes, no evidence of baffles, fibreglass or similar filling has been found.
If remanufacturing, note that the angled corners were not cut away to clear the chassis rails (as might be expected) and a 19" long, oval box will still fit into the car without problem.

Gasket for the front exhaust to manifold joint.
Material:- Copper - Asbestos - Copper sandwich.
Note that the sizes have been measured from the exhaust downpipe and not from a gasket. The 1.1/2" hole could be larger on the gasket.

P D Gough