Diagrams kindly supplied by Joseph Lucas Ltd.
The conversion of single-dipping headlamp units to double-dipping is illustrated by the above two diagrams. On the left is shown the wiring of a 1933 Jowett of the original single-dipping variety, while the right-hand diagram illustrates the re-wiring necessary for double-dipping, drawn to the same scale. Conversion sets are NOT available from Lucas, but this is a straightforward job if the wiring pattern is followed. To avoid dazzle, it is essential to replace the original glass headlamp units with the modern design to accommodate the necessary twin-filament bulbs; unfortunately, not all pre-war lamp housings will accept the later light units. The price of light units alone is approximately 25s. each.