The steering column and rack section covers the complete rack-and-pinion mechanism that gives the TD and TF their direct, responsive steering, a Y-type-derived layout that replaced the TC's Bishop cam-and-peg system and set the pattern for every MG sports car that followed. The rack housing is specific to left-hand and right-hand drive, and three documented production changes affect the internal rack components and tie rod fixings.
Steering Rack
The steering rack is available new (without tie rods) and reconditioned on a customer's own unit reconditioned basis (with tie rods), in both RHD and LHD specifications. The rack and pinion internal set is available separately for overhauling an existing housing. The pinion runs on upper and lower thrust washers and a tail bearing, with 0.005" and 0.007" shim sizes available for endfloat adjustment. A spring-loaded damper pad on the pinion side loads the rack against the pinion to eliminate backlash; the pad, spring, cap and 0.003" and 0.010" damper shims are individually available, as is the grease nipple that lubricates the rack itself.
The rack underwent three production changes documented in the factory records. The inner tie rod ball housing was redesigned at chassis TD/11111 in October 1951, and earlier and later inner ball housings are not interchangeable. The outer tie rod ends received improved seals at chassis TD/25973 in March 1953. On the TF, the tie rod, ball stud and grease nipple threads all changed from BSF to Unified at chassis TF/4760 in April 1954, owners should verify thread form before ordering replacement tie rods or fittings on a TF.
The inner ball housing comprises separate male and female halves, with ball seat shims in 0.003", 0.005" and 0.010" thicknesses for adjustment during overhaul.
Rack Gaiters
The rubber rack gaiters seal the rack housing against water and grit ingress, which destroys the rack's internal surfaces and the tie rod inner ball joints rapidly once admitted. The gaiter kit includes two gaiters with their clips; large and small clips are also available separately. Split or perished gaiters should be replaced immediately rather than at the next major service.
Steering Column
The steering column is telescopically adjustable for reach with a small amount of rake adjustment, a feature inherited from the Y-type saloon and unusually sophisticated for the era. The inner and outer column tubes, upper and lower felt bushes, upper clamp (column to body bracket) and lower clamp with its distance tubes are all available, along with the leather fume excluder, plate and Supergrip clip that seal the column where it passes through the bulkhead. The column connects to the rack pinion through a flanged joint using three bolts with six rubber bushes, fitted in pairs around each bolt to provide vibration isolation between the steering wheel and the rack. Deterioration of these bushes introduces play that is often mistaken for rack wear; checking and renewing the flange bushes is the first step in diagnosing on-centre vagueness.
Track Rod Ends
The track rod end ball joints connect the tie rods to the steering arms on the stub axles. Each assembly is supplied with its own gaiter, securing clip, slotted castellated nut, split pin and grease nipple. The split pin must always be renewed at reassembly, and the track rod end grease nipples require periodic attention as part of the chassis lubrication schedule.