The MGA's Lucas 12-volt positive-earth electrical system was state of the art for 1955 but shows its age against modern expectations. The dynamo struggles to keep the battery charged at low engine speeds, especially with modern lighting or accessories. The inertia starter needs a healthy battery to spin the engine at cranking speed. Factory lighting output falls well short of what modern traffic demands.
And the positive-earth architecture itself rules out most modern electrical accessories without conversion. This section addresses these limitations in nine sub-categories, allowing owners to modernise selectively according to how the car is used.
High Output Alternators & Dynamos
A modern alternator conversion replaces the factory dynamo with a negative-earth alternator offering higher peak current, significantly better output at low engine speeds, and no separate control box required. For cars running modern lighting or accessories, this is the single most valuable electrical upgrade available to an MGA owner. Conversion typically involves switching from positive to negative earth throughout the car. Uprated original-specification dynamos are also stocked for owners retaining positive earth.
Hi-Torque Starter Motors
Modern pre-engaged gear-reduction starter motors spin the engine faster and need less battery current than the original Lucas M35G-1 inertia starter. Particularly valuable on cars with higher-compression engines (including the Twin Cam), with uprated ignition, or with aged batteries where the original starter can struggle to turn the engine over on cold mornings.
Performance Ignition
Performance ignition systems replace the original Lucas points-and-condenser setup with electronic contactless triggering, eliminating the need for regular points adjustment and giving more consistent spark timing across the rev range. Options range from drop-in electronic points replacements inside the original distributor body to fully-electronic distributors. Performance sports coils pair with electronic ignition for hotter spark output.
Lighting Upgrades
Halogen headlamp bulbs, LED sidelamp and indicator bulbs, LED rear lamp bulbs and similar upgrades address the MGA's limited factory lighting output without requiring a full lamp-unit change. The Lighting Upgrades node also covers higher-output replacement headlamp units for cars where the factory F700 lamp housings are being replaced rather than just re-bulbed.
Hazard Lights & Relay Kits
Hazard lights, all four indicators flashing simultaneously, were not fitted to any MGA from factory. A hazard flasher upgrade is a safety improvement for any MGA regularly used on modern roads, and is mandatory equipment in some European countries. Relay kits are also stocked for installing auxiliary lamps, horn upgrades, and other accessories without overloading the factory wiring.
Horns
The factory Lucas Windtone WT618-L low-note horn (and optional WT618-H high-note pair) are covered under MGA Switches & Horns. This Upgrades node covers alternative horn options, louder air horns, modern dual-tone horns, and higher-output electric horns, for cars where the factory horn output is inadequate for modern traffic.
Wash/Wipe
Washer and wiper upgrades include modern wiper blades in longer lengths for better screen coverage, uprated wiper motor specifications, and electric windscreen washer pumps replacing the factory manual plunger pump.
Battery Chargers & Conditioners
Smart battery chargers and maintainers for classic cars kept in occasional use, plus battery conditioning products. Full detail under the Battery Chargers & Conditioners node within this section.
Electrical, general
The Electrical sub-node covers general-purpose electrical items that don't fit neatly into other categories, accessory sockets, modern gauges, electrical connectors, auxiliary switches and similar.
Positive earth vs negative earth
Many upgrades in this section, alternator conversions, modern radios, LED bulbs, some electronic ignition systems, require conversion from factory positive earth to negative earth. Conversion requires the dynamo (or alternator), polarised accessories (radios, fuel pumps, coil), and battery connections to be changed or re-polarised. Partial conversions (mixing positive and negative earth components) will damage components. Plan the negative-earth conversion for the whole car simultaneously rather than piecemeal.
Ordering considerations
Electrical upgrades should be approached with the car's overall electrical condition and use case in mind.