Replacement electric horns provide a direct-fit solution for owners renewing tired original-equipment horns while keeping the period-correct visual appearance and the original electrical configuration. The horns are constructed in the Lucas pattern that was original equipment across classic-MG production, a steel housing with a chromed or polished bell, mounted to the original brackets and operating on the original electrical circuit without modification. After decades of exposure to road spray, salt, and temperature cycling, the original horn units on most surviving cars will have deteriorated, the internal contacts corroding, the electromagnetic coil losing strength, and the diaphragm hardening, all combining to produce a weak, raspy, or intermittent sound that is inadequate for safe road use in modern traffic.
High-Tone & Low-Tone Specifications
Classic-MG production typically specified a matched pair of horns, one tuned to a higher note and one to a lower note, the two operating simultaneously to produce a two-tone sound that was more distinctive and audible than a single horn could produce alone, wired in parallel from the horn-push so that both sound together. The pitch of each horn is set by the internal mechanism, a vibrating armature that strikes a contact at a specific resonant frequency with the housing's bell tuned to amplify the chosen note, and the two-tone combination produces a richer, more attention-getting sound. Both units should always be replaced together, as an ageing partner will produce an unbalanced note and fail shortly after, while replacement horns in chrome and black finishes are available across the range, the visual appearance faithful to the original Lucas equipment, which matters for cars restored to concours specification where the period-correct finish in the engine bay or behind the grille is as important as the sound performance.
Installation & Diagnosis
Replacement horns fit into the original-equipment mounting brackets without modification, typically a bracket on the inner wing or behind the grille depending on the application, with flexible mountings between the horn and the bracket isolating the horn vibration from the body structure to prevent the resonance that can cause a tinny or buzzing sound from the bodywork. The electrical connections use the original-equipment terminal arrangement, the supply wire connecting through the existing horn-push and the earth made through the mounting bracket to the chassis, with no modifications to the wiring loom needed. Before replacing a non-functioning horn, the electrical connections should be checked, as a 12-volt test at the terminal confirms power delivery and cleaning the earth connection often resolves intermittent operation, corrosion on the earth connection at the mounting bracket being one of the most common causes of weak or non-functioning horns and best cleaned back to bare metal during fitting. A horn that sounds weak or distorted may have water inside the body, and on cars fitted with a horn relay providing high-current switching for both horns, the relay should be checked if operation is intermittent or only one horn sounds.
The Air Horns section covers the air-horn alternative for owners wanting substantially louder output.