The MGA wiring loom carries every electrical circuit in the car, charging, ignition, lighting, instrumentation, horn, wipers, washer, heater and accessories, from the Lucas control box and fuse box at the bulkhead out to the individual components around the car. Over more than sixty years of service, the original looms have typically deteriorated beyond safe use: PVC insulation cracks, cloth braid perishes, cables oxidise inside their sleeves, and connector terminals corrode. A complete loom replacement during restoration is one of the most significant improvements an owner can make to an MGA's long-term reliability, and is frequently the only practical route on cars where the original wiring has been bodged or damaged in service.
Factory loom construction, cloth or PVC
MGA wiring loom construction changed during production. Early 1500 cars (until approximately 1958) used individual cloth-covered wires inside a black outer braid with a six-ply white cross pattern.
Later cars used PVC-insulated wires inside a plastic-covered outer; the harness braiding carries a yellow tracer on pushrod cars and a white tracer on Twin Cams. Some late Mk II cars had a grey rather than black harness cover. The headlamp wires were always cloth covered, throughout MGA production, because cloth insulation handled the heat of the headlamp circuit better than the PVC specification of the period. The facia wiring loom cover has a brown tracer with a white cross across all pushrod cars.
Cloth vs vinyl, the restorer's choice
MGOC Spares stocks complete wiring looms in both construction types, matching the factory option of the period for owners restoring to factory-correct specification, or for owners modernising the harness for long-term reliability. The cloth loom is built with cloth-braided outer covering, the factory specification for early 1500 cars; for concours restoration of an early 1500 or for any MGA being restored to the original cloth-covered appearance, the cloth loom is the correct choice. The vinyl loom is built with modern PVC-insulated wires and modern plastic outer covering, matching the factory specification of later 1500 cars and all 1600 cars but built to current-specification insulation that resists cracking and oil damage better than the originals.
For cars not being judged at concours events, the vinyl loom is the preferred choice for long-term reliability. Both constructions are built to the factory wiring diagram for the variant, the same circuits, the same colour coding, the same terminal connections, the same routing to the Lucas-pattern components. The choice between cloth and vinyl is cosmetic and material rather than functional.
Fitment ranges, 1500 (55 to 59) and 1600 (59, 62)
Two fitment ranges are stocked, matching the main MGA production split. The MGA 1500 loom (55>59) covers all 1500 production cars, 1955 to 1959, and fits the 1500 harness arrangement with the original Lucas RB106-2 control box using screw terminals (pre-Lucar specification). The MGA 1600 / 1600 Mk II loom (59>62) covers 1600 and 1600 Mk II production cars, 1959 to 1962, and reflects the harness changes introduced at car/chassis 74489 when Lucar snap connectors were adopted for the dynamo harness on the 1600, along with the revised Mk II rear lamp wiring for the type 647 lamp units. Each fitment range is stocked in both cloth and vinyl construction, giving four loom specifications to choose from.
Twin Cam and De Luxe, loom notes
Twin Cam MGA harnesses differ from the pushrod specification in several respects, the harness braiding carries a white tracer rather than yellow; the separate brake and clutch master cylinder hydraulic routing requires different under-bulkhead harness routing; and some detail circuits differ. Owners restoring a Twin Cam or De Luxe harness should contact MGOC directly to confirm loom availability for these variants, as the pushrod looms stocked on this page are not a direct fit.
Ordering considerations
Loom selection requires two decisions: the variant (1500 for 1955 to 1959 cars, or 1600 / 1600 Mk II for 1959 to 1962 cars), and the finish (cloth for period-correct early-1500 restoration, or vinyl for modern construction and later-specification cars). Installation should be carried out with the car dry and clean and with all electrical components off the car, as the harness is a major under-dash and engine-bay fit requiring access to mounting points, grommets, clamps and connectors throughout the vehicle. Allow generous time for the fit, a full loom replacement is a day or more of careful work even for an experienced auto electrician.