The MGB power unit is suspended on three mounting points, two engine mounts at either side of the front of the engine to the body side members, and a single transverse gearbox mounting crossmember below the rear of the gearbox. This three-point arrangement remained the basis throughout production, though the specific components used changed between the chrome bumper and rubber bumper periods, and differ depending on which gearbox is fitted.
Engine Mountings
The engine mountings changed between the chrome bumper and rubber bumper eras. Chrome bumper cars use a different mounting rubber and bracket arrangement to rubber bumper cars, and the packing plates used to achieve correct engine alignment also differ between the two.
On chrome bumper cars, an engine surge bracket is fitted on both sides where HS4 carburettors are fitted, though this arrangement was revised when HIF carburettors were introduced, from which point the left-hand surge bracket was replaced by a modified type while the right-hand original bracket was retained. On three-synchro roadsters, the surge brackets are not fitted at all. Correctly identifying the chrome bumper or rubber bumper specification, and the carburettor type, is therefore important when sourcing engine mounting hardware.
Gearbox Mountings
The gearbox mounting arrangement also differs across the production run, and most significantly between the three-synchromesh and four-synchromesh gearbox applications, and between the chrome bumper and rubber bumper four-synchro cars. Three-synchro cars, both roadster (GHN3) and GT (GHD3), use a different crossmember and mounting configuration to four-synchro chrome bumper cars, which in turn differ from rubber bumper four-synchro cars. The gearbox mounting rubbers are shared across some variants but not all, the correct rubber depending on the gearbox type and bumper specification, and the crossmember itself is a separate, body-year-specific part.
Steady Rod
An additional component in the gearbox mounting system is the steady rod and its associated hardware. On three-synchro cars, the steady rod system uses a pin, rubber bushes, a steady rod, a bracket, spacer tube, and buffer plates to locate the rear of the gearbox laterally. Four-synchro chrome bumper cars use a different steady arrangement with upper and lower brackets, a steady pin and grommet, while rubber bumper four-synchro cars have a revised system using a separate steady rod, bracket, and buffer arrangement. The steady pin and grommet are shared between some four-synchro variants but the brackets and steady rod itself are specific to chrome or rubber bumper specification, so ordering by model year and gearbox type is essential to ensure all components are compatible with one another.
Range
The range covers engine and gearbox mounting components for all MGB variants, including engine mounting rubbers, packing plates, mounting brackets, gearbox mounting rubbers, steady rods, steady rod pins, steady bushes, steady brackets, gearbox crossmembers, and all associated fixings for both chrome bumper and rubber bumper cars across three-synchro and four-synchro applications.