A boss kit is the column-end hardware that adapts an aftermarket steering wheel to the specific spline pattern and column-end arrangement of a particular classic MG. The aftermarket wheel manufacturers, Moto-Lita, Mountney, Lecarra, Momo, and the wider brands, produce wheels with standardised mounting patterns at the rear, allowing one wheel design to fit any car for which an appropriate boss kit is available, the boss kit providing that adaptation by bolting to the splined end of the car's steering column on one side and to the standard mounting pattern of the wheel on the other. Selecting the correct boss is as important as choosing the wheel itself, as fitting an incorrect boss is the most common cause of an installation that wobbles, fails to engage the horn-push contact properly, or cannot be secured safely.
What the Boss Kit Contains
Each boss kit gathers the components needed for a complete column adaptation. The boss itself is a cast-aluminium hub that fits over the splined end of the steering column, finished with a polished centre cap and MG octagon badge that present a clean visual finish where the wheel meets the column, the retaining nut securing the boss to the column splines, and the screw fitting kit needed to secure the wheel to the boss flange. The multi-drilled PCD, pitch circle diameter, means a single boss accepts wheels with either a six-hole or nine-hole mounting pattern, so the same boss is compatible with the principal aftermarket ranges including Moto-Lita and Classic without changes, while dedicated boss patterns cover the twelve-hole Momo arrangement. Together, the components allow an aftermarket wheel to be fitted to a classic MG with the same finished appearance as if the wheel had been designed specifically for that car.
Polished horn pushes are available separately for installations where the original or a matched replacement horn push is being fitted at the same time.
Application-Specific Variations
Boss kits are specific to the application, the MGA, MGB, MGC, Midget, and other applications each using different patterns, partly the spline pattern at the column end which varies by car, partly the column-end length, some cars having longer column ends that require deeper boss hubs, and partly the cosmetic finish, different cars using different visual conventions at the column-to-wheel interface. Some applications have multiple boss-kit options, the MGB chrome-bumper and rubber-bumper columns using different splines and not being interchangeable, with a further dedicated nine-hole boss for the 1968 export-only MGB and MGC where the column spline differs from the standard home-market fitment. The Midget similarly has variants matching the production date and horn arrangement, sub-variants covering dashboard horn, stalk horn, and centre horn push arrangements, the horn wiring connecting through the boss with some bosses including an internal horn contact and others routing through a column slip ring. The right boss kit is matched to the chassis number, production date, and original-equipment specification at the point of order, and confirming the model year, market specification, and horn arrangement before ordering avoids fitment surprises during installation.
Quick-Release & Brand Compatibility
Quick-release boss kits, where the wheel can be released from the column with a single lever, are stocked for applications where the owner wants to remove the wheel for security when the car is parked, or for cars used in competition where regular wheel removal is part of the event procedure, the quick-release mechanism engineered to provide secure attachment during normal driving while allowing the wheel to come off in seconds. Moto-Lita boss kits are produced as a matched accessory to Moto-Lita wheels, ensuring perfect compatibility with that range and a finished installation that matches the quality of the wheel itself, also widely fitted in combination with other branded wheels using the multi-drilled flange. Classic boss kits offer the same essential function at a more accessible price point, suitable for installations where the wheel is also from a similar mid-range source.
When fitting, the steering must be set to the straight-ahead position before the boss is located on the spline so that the new wheel's spoke positions are correct relative to the road wheels, and on collapsible columns great care is needed during fitment to avoid collapsing the column.