The MGA engine and gearbox are mounted to the separate chassis frame at three points: two engine mountings at either side of the front of the engine, carried on brackets bolted to the chassis front crossmember bridge piece, and a single gearbox mounting at the rear of the gearbox bellhousing. This three-point arrangement isolates engine vibration from the chassis while maintaining precise alignment between the engine, gearbox, and propeller shaft.
Engine Mountings
The engine mounts are rubber-bonded units that absorb vibration and allow controlled engine movement under load. Worn engine mounts allow excessive movement, which places stress on the exhaust manifold joint, throttle linkage, and cooling hoses. On the MGA's separate chassis, where the engine is bolted to the chassis rather than integrated into a monocoque structure, worn mounts also allow the engine to shift position relative to the gearbox, potentially causing clutch drag and difficult gear selection. The engine mounting specification was consistent across all pushrod variants.
The Twin Cam and De Luxe models used differently positioned engine mountings owing to the different engine and chassis arrangement, Twin Cam and De Luxe mountings are not interchangeable with pushrod items. On Twin Cam cars, a packing plate was added to the left-hand engine mounting from chassis number 528 (June 1958) to improve clearance between the starting handle dog and the steering rack.
Gearbox Mounting
The gearbox mounting sits below the rear of the bellhousing and supports the combined weight of the gearbox and the rear of the engine. It is a rubber-bonded unit bolted between the bellhousing and a crossmember on the chassis. The mounting plate between the gearbox and the chassis was changed at chassis number 61504 (January 1959) when the 15GD engine was introduced with its raised starter motor position, the revised plate accommodated the different bellhousing-to-chassis relationship.
This means that the gearbox mounting plate differs between 15GB and 15GD engines, and the correct type must be identified before ordering.
Chassis Bridge Piece and Mounting Brackets
The front crossmember bridge piece, the welded-in chassis section spanning the front axle line that carries both the front engine mountings and the inverted cup housings for the front suspension coil springs, is common across all pushrod MGAs (1500, 1600, and 1600 Mk II). The Twin Cam and De Luxe chassis use a differently configured bridge piece, pre-drilled for oil cooler pipes and with differently located engine and body mounting points, reflecting the Twin Cam's different engine position. The brackets bolted to the bridge piece that carry the engine mounts are also specific to the engine type fitted, with separate left-hand and right-hand brackets for pushrod applications.
Signs of Worn Mountings
Worn engine or gearbox mounts manifest as excessive engine movement visible when the engine is revved with the bonnet open, clunking noises when the clutch is engaged or the throttle is applied and released, and poor gear selection caused by misalignment between the engine and gearbox input shaft. On the MGA, where the engine, gearbox, and bellhousing are a single unit, misalignment at the rear mounting also affects the propeller shaft angle and can cause vibration at speed.
Ordering Notes
When ordering mountings, the key identification points are: pushrod versus Twin Cam (different engine mounting brackets and chassis mounting points), and 15GB versus 15GD (different gearbox mounting plates, changing at chassis number 61504). All 1600 and Mk II cars use the 15GD-era gearbox mounting plate. Provide the engine prefix and chassis number when ordering, and note that the left-hand and right-hand engine mounts are different parts and are supplied individually.