The stub axle and hub assembly is the interface between the front suspension and the road wheels, the stub axle provides the wheel bearing journals and brake backplate mounting, while the swivel pins and trunnions allow the assembly to pivot for steering. This section contains some of the most chassis-number-dependent components in the catalogue, with the front hub and drum existing in four distinct specifications across the production run.
Stub Axles
The stub axles are handed (RH and LH) and exist in BSF (TD to chassis 12284) and Unified (TD from 12285, all TFs) thread, supplied on a customer's own unit reconditioned basis. They carry the swivel pin bores, bearing journals, and brake backplate mounting. Wear affects steering precision, bearing security, and brake effectiveness, bores should be inspected before fitting new components.
Swivel Pins and Trunnions
The swivel pin runs vertically through the upper and lower trunnions, providing the steering pivot. Both swivel pins (king pins) and the trunnions are handed left and right. Each trunnion contains a pressed-in bush running on the swivel pin, with grease nipples for routine lubrication. The complete trunnion seal kit covers eight top and bottom seals plus four swivel pin to trunnion seals, enough for both sides of the front suspension and the practical specification for any rebuild.
Trunnion bushes wear progressively, especially with a neglected greasing schedule. Worn bushes give a clunking noise over bumps and play at the steering wheel. Bushes can be pressed into the trunnion bodies, but the bore should be checked for ovality first, a worn trunnion is best exchanged for a serviceable unit.
Steering Arms
Steering arms bolt to the stub axles, located by Woodruff keys and retained by stiff nuts and plain washers, transmitting the steering rack's movement via the track rod ends. Arms are catalogued in BSF thread, the arm-to-stub-axle thread did not change at the 12285 switch. The arm-to-stub-axle connection must be tight and correctly keyed, a loose or incorrectly seated arm is potentially dangerous.
Front Hub and Brake Drum Specifications
The front hub and drum exists in four specifications for steel-wheeled cars by chassis number. Earliest TDs to chassis 4250 used a two-piece hub-and-drum with felt retainer and cap (from the TC). From chassis 4251 (Nov 1950) a single-casting hub-and-drum was introduced, still with felt cap. From chassis 6035 (May 1951) a press-on steel grease cap replaced the felt.
From chassis 12285 (late 1951) wheel studs and nuts changed from BSF to Unified. All TFs use the post-12285 specification. The wheel studs (ten per pair of hubs, five per hub) and matching wheel nuts are thread-specific to the hub: BSF for TD to chassis 12284, Unified for TD from chassis 12285 and all TFs. They are pressed into the hub face and must match in thread.
Wire Wheel Hubs and Spinners
Wire-wheeled cars use separate splined front hubs (RH and LH) with the drum retained by twelve drum-retaining studs and lock tabs. Hub washers and slotted nuts differ between BSF and Unified specifications; slotted nuts are handed (RH thread one side, LH the other) so road movement tightens them. Spinners are available in two-ear and octagonal styles in LH and RH thread by side. A separate spare wheel spinner with MG medallion is catalogued.
A rubber plug fits the adjuster access hole. A complete wire wheel conversion kit is available for both TD and TF, providing the splined hubs, brake drums with fixings, two-eared spinners, a copper or copper-and-hide hammer, a spare wheel carrier adaptor, and a spare wheel spinner, everything needed to convert a steel-wheeled car to wire wheels.
Wheel Bearings and Hub Seals
The inner and outer front wheel bearings (taper-roller) and the bearing spacer between them are common across all TD and TF specifications. The hub oil seal sits behind the inner bearing and prevents grease migrating into the drum, a failed seal is a common cause of one-side brake fade, as escaped grease coats the linings and dramatically reduces friction. Bearings should be inspected for play and roughness whenever the hubs are removed.
Ordering Considerations
The chassis number is the most important reference when ordering stub axles, hubs, drums, wheel studs and nuts, washers, and slotted hub nuts, all thread-specific (BSF or Unified). Wheel type determines hub and drum specification. Bearings, spacers, hub seals, and trunnion seals are common across all specifications. Steering arms are BSF thread regardless.
For wire-wheel hub nuts, specify side (RH or LH) for the correct thread direction.