The Gearbox and Axle Accessories catalogue covers cross-model items that fall outside the model-specific gearbox and axle sections, primarily the alternative crown-wheel-and-pinion ratios available for the rear axle, and the clutch tools needed for any gearbox-out work. Where the the dedicated model sections cover the standard clutch, gearbox and axle components for each car, the Accessories section is the home for the specialist items that allow owners to recalibrate the transmission to a different intended use.
Crown Wheels and Pinions
The Crown Wheels and Pinions section covers the alternative final-drive ratios available for the MGB and MGC rear axle. The standard MGB axle ran a 3.9:1 final drive for most of its life, with 3.7:1 fitted to overdrive cars to suit the taller overall gearing. Higher-ratio options, typically 3.7:1 in a non-overdrive car, or 3.5:1 for an overdrive car used predominantly on motorways, drop engine rpm at cruise and dramatically reduce noise and stress on long runs. Lower-ratio options, 4.1:1 and similar, give faster acceleration at the cost of cruise refinement, and suit cars used in hilly country or for sustained low-speed driving.
The crown wheel and pinion is supplied as a matched pair with the appropriate side and end pinion bearings and the necessary shims for setting up the backlash. The work is specialist, setting up the pinion depth, the crown wheel backlash and the bearing preload correctly is essential, and is best done by a workshop with the appropriate gauges. The Performance Engines section covers the rear-axle recalibration choices for cars that have also gained a tuned engine.
Clutch Tools
Clutch Tools, also accessible through the Tools catalogue, cover the items that make a gearbox-out clutch change a manageable job. The principal item is the clutch alignment tool, a stepped or splined mandrel that locates the clutch plate centrally on the flywheel during fitment so the gearbox input shaft can pass through it cleanly on reassembly. A misaligned clutch plate is one of the most common reasons a gearbox refuses to mate up to the engine, leaving an awkward and time-consuming problem in the bottom of a workshop pit. The alignment tools are stocked in the diameters and splines used across the classic MG range.
Clutch slave-cylinder push-rod adjustment tools, flywheel-locking tools and pilot-bearing pullers complete the specialist set.
Gearbox Upgrade Cross-Reference
Where an owner is moving beyond a like-for-like rebuild, fitting a five-speed conversion in place of the original four-speed-plus-overdrive gearbox, or moving to a stronger axle to handle the torque of a V8 conversion, the Gearbox & Axle Upgrades sub-section is the home for the upgrade-specific items, with the dedicated MGB, Midget, MGA, MGC and MGB GT V8 sections covering the model-specific internals. The Accessories Gearbox and Axle catalogue is the cross-model home for the items that allow the transmission to be recalibrated, while each model's own section is the home for the gearbox internals, axle housings and the specialist work that those components require. The technical team is available to advise on the right combination of gearbox, final-drive ratio and overdrive option for any given use case.