The TD and TF use Lucas DR-series wiper motors with mechanically very different installations. The TD layout was revised mid-production at chassis TD/22315 (November 1952), the same chassis at which NA-export TDs received factory direction indicators and the windscreen glass profile changed to suit the relocated motor.
TD Wiper System, Early Specification (to Chassis TD/22314)
Early TDs use a wiper motor on the RH side of the windscreen frame top rail (LH on LHD cars) driving two wiper arms through a coupling bar from the motor's output spindle. The motor incorporates a single bearing. Two wiper arms (RH and LH) and a single coupling bar make up the linkage.
Early TD windscreen glass is specific to the side-mounted motor position.
TD Wiper System, Late Specification (from Chassis TD/22315)
From chassis TD/22315 (November 1952) the motor was relocated to the centre of the top rail. This required a redesigned linkage: three wiper arms now drive the blades (RH, LH, and a centre link arm tying the two outer arms together) with a different coupling bar. The mechanism uses two bearings rather than one. The windscreen glass was also revised at the same chassis to suit the centre-mounted motor.
TD Wiper Motor and Service Components
The TD wiper motor itself is the same unit across all TDs, available new and on a one-for-one reconditioned exchange basis. The motor is a Lucas DR-series unit (DR1 or DR2, the brush kit covers DR1, DR2, and DR3). Carbon brush set, motor cover with integral handle and switch, handle and screw, and the extension loom to the main loom are all available individually. Wiper blades and rubber stop blocks are common across all TDs.
TF Wiper System
The TF uses a fundamentally different drive arrangement with the same Lucas DR-series motor type. A single motor mounted on the bulkhead behind the dashboard drives a flexible toothed rack inside two casing tubes. The casings run through a bulkhead grommet to two wheelboxes, one per spindle, converting the rack's linear motion to rotational at each wiper spindle. The rack and casings are supplied in long lengths cut to fit.
The motor is available new and reconditioned on a customer's own unit basis. The casing was originally wrinkle-finish, aerosol wrinkle paint is available for refinishing.
TF Wiper Controls
A defining feature of the TF system is dual control: a knurled wiper knob is fitted in each glovebox. The driver's-side knob powers the motor; the passenger-side knob has no electrical function and engages the passenger wiper with the drive. With the passenger knob disengaged, only the driver's wiper operates, useful for solo driving in light rain or when battery state is marginal. Both knobs are available as service items.
TF Wheelboxes and Sealing
TF wheelboxes are handed: a RH wheelbox for one spindle and a LH wheelbox (with integrated switch contact) for the other. They are sealed to the scuttle by rubber bushes (complete set or individual). A failed wheelbox is the commonest TF wiper failure, the rack pushes through a worn wheelbox without engaging, leaving the motor running but the blade stationary.
Wiper Arms and Blades
The TF uses a wiper arm and blade dedicated to the car (TF arm and TF blade catalogued separately). The arms are bayonet-mounted to the wheelbox spindles, and standard modern replacement blades fit the original arms. Both TD and TF use a standard rubber-element design; silicone-element blades are a modern alternative for owners using the cars in heavy rain.
Polarity and Modern Improvements
The Lucas DR-series motors are series-wound DC units functioning on either positive or negative earth with the connections made for the chosen polarity. The motor itself does not need changing on conversion, only the supply wiring polarity. Intermittent-wipe converters adding a delay function (Weather Equipment Upgrades) and silicone wiper blades giving better cold-weather wiping and longer life are popular modern improvements.
Ordering Considerations
TD ordering: early TDs to chassis 22314 use the side-mounted two-arm specification; TDs from 22315 use the centre-mounted three-arm specification (with centre link arm). The motor itself is the same across both. TF components are common across production, with racks and casings supplied in long lengths cut to fit. New motors are supplied outright; reconditioned units are exchange (TD) or customer's own unit (TF).
The same brush kit covers DR1, DR2, and DR3.