The MGA uses a short one-piece propeller shaft connecting the gearbox output to the rear axle input, made by Hardy Spicer and finished in black. The shaft incorporates universal joints with needle roller bearings at the front and rear ends. Two distinct production specifications of propshaft were used during MGA production, along with a minor 1500-only refinement between them, and the specification fitted depends on the chassis number of the car.
Replacement propshafts, universal joints and associated hardware are available matched to each specification.
Early 1500 specification
The earliest 1500 propshaft used a reverse-spline sliding joint between the gearbox output shaft and the front universal joint, the shaft slides onto a splined extension of the gearbox output, rather than carrying a sliding joint within the shaft itself. From car/chassis 20753, this early-pattern propshaft was modified with a dust cover added at the front. Cars between the start of 1500 production and chassis 20753 therefore use the original-pattern shaft without the front dust cover; cars from 20753 onwards (within the 1500 range pre-61504) use the modified shaft with the dust cover.
Revised specification from chassis 61504
A more substantial revision occurred at car/chassis 61504, coinciding with the introduction of the 15GD engine. The revised propshaft incorporated the splined sliding joint within the shaft itself, just behind the front universal joint, rather than the reverse-spline arrangement used on the earlier pattern.
The revised shaft connects to the gearbox through a four-bolt flanged connection, with a matching flange on the gearbox output shaft. The guide notes that the revised propshaft was also fitted to a few earlier cars ahead of the formal 61504 breakpoint, so chassis numbers immediately before 61504 may be found with either specification depending on build date.
1600, 1600 Mk II and Twin Cam propshaft
The revised propshaft introduced at 61504 was carried over without further change to all 1600 and 1600 Mk II cars. It was also fitted to all Twin Cam models from the start of Twin Cam production, so Twin Cam cars do not have the earlier reverse-spline propshaft arrangement at any point in their production run.
Universal joints and serviceable components
Both the front and rear universal joints on the MGA propshaft use needle roller bearings. The joints and their bearings are available as service items, as are replacement complete propshafts in each specification. The sliding joint (whether the early reverse-spline pattern or the later internal-spline pattern) is similarly a service item, and the dust cover added from chassis 20753 is available separately for earlier shafts converted to the later arrangement during restoration work.
Ordering considerations
The propshaft specification is determined by chassis number. Cars from the start of 1500 production to chassis 20753 use the earliest pattern without the front dust cover. Cars from chassis 20753 to approximately chassis 61504 use the pre-61504 pattern with dust cover. Cars from 61504 onwards, including all 1600, 1600 Mk II and Twin Cam cars, use the revised pattern with internal sliding joint and four-bolt gearbox flange.
Where a chassis number falls immediately before 61504, the specific propshaft fitted should be confirmed against the shaft itself, since a small number of cars received the revised specification ahead of the formal breakpoint. When ordering a complete propshaft or replacement universal joints, the chassis number and inspection of the existing shaft together determine the correct specification.