A working horn is a legal requirement for any road-going classic MG, and the original Lucas horns fitted to the cars during production frequently fall short of modern expectations, both for sound output and for reliability after several decades of service. This section gathers the principal options for owners renewing or upgrading the horn system, with replacement Lucas-style electric horns matching the original equipment alongside twin-tone air horn kits for owners wanting a louder and more distinctive sound.
Most cars in the range used twin horn units of slightly different note pitch giving the characteristic two-tone British road-car sound, operated via the horn push, which closes the horn relay circuit and energises both horn units simultaneously, the push being on the steering-wheel centre on most applications.
Replacement Electric Horns
The replacement electric horns are direct-fit units matching the original Lucas equipment, stocked in the high-tone and low-tone specifications used on classic-MG production and typically supplied as a matched pair for cars where both horns were originally fitted, with the appropriate mounting brackets, electrical connections, and mounting hardware. The visual appearance is faithful to the original Lucas units, typically a black-painted steel housing with a chromed or polished bell and the appropriate trade-mark on the housing for cars where this matters to the owner's restoration approach. The horns operate on the original-equipment electrical system without modification, the existing horn-push, the existing horn-relay where fitted, and the existing wiring all continuing to function correctly with the replacement horns in place, and they fit into the original mounting locations, typically on the inner wing or behind the grille area. Single-tone horns are available as a more economical alternative where the twin-tone arrangement is not required, the single horn providing adequate warning function with simpler installation and lower cost.
Air Horn Kits
The twin-tone air horn kits are for owners wanting a louder and more attention-getting horn than the original electric specification can produce, useful for cars used on busy modern roads where the original horns can be inadequate. The air horn kit includes a small electric compressor typically mounted in a discreet location in the engine bay, the air horns themselves as a matched high-tone and low-tone pair, the air-supply hose from the compressor to the horns, and the supporting electrical wiring to operate the compressor from the existing horn push. The sound produced by a quality air horn pair is dramatically louder and more distinctive than the original electric horns, typically 110 to 120 decibels compared with 90 to 100 for the original equipment, and the period-correct trumpet shape of the horns themselves gives the installation a sporting visual character that suits classic MGs particularly well, though the compressor and air-horn assembly is larger than the original electric horn installation and may require some packaging consideration in the engine bay.
Application & Installation
Both horn types are stocked for the principal classic-MG applications with the appropriate mounting brackets and wiring arrangements for each car. The replacement electric horns typically fit into the original mounting locations without modification, mounting on the original brackets using the original wiring and providing direct replacement for failed originals. The air horn kits require slightly more involved installation, finding suitable mounting locations for the compressor and the two horns, routing the air hose between them, and connecting the compressor's electrical supply to the existing horn circuit through an appropriate relay, as the compressor draws more current than the original electric horns and the relay protects the original horn-push contacts from the higher load. The trade-off between the two approaches is appearance versus sound output, replacement electric horns preserving the period appearance while air horn kits substantially improve the sound output at the cost of a slightly more involved installation.
The technical team is available to advise on the right specification for a specific car and intended use.