This section covers the MGA threshold plate set, the chrome-plated plates fitted across the door sill at each side of the car, where the door opening meets the floor. Threshold plates serve two functions: they protect the painted sill from scuffing damage caused by feet entering and leaving the car (a significant wear point on any car after years of use), and they provide a finished decorative appearance at the door opening, typically incorporating an MG octagon motif.
Set fitment, pair
The MGA threshold plate set is supplied as a matched pair, one for each side of the car (left and right). The plates are identical in shape and finish, mounting across the sill aperture with screws into the underlying sill structure. Both plates should be fitted together for a uniform appearance across the car's interior; fitting only one side leaves the unfinished opposite side visually inconsistent.
Why threshold plates matter
The MGA's painted sills are exposed at the door opening and suffer significant wear from regular entry and exit. Footwear contact with shoe soles (particularly with grit or stones embedded in the tread) abrades the painted finish where occupants step onto the sill. Heel contact from sliding feet across the sill (common when getting into a low sports car) drags the heel across the paint, causing scratches that show against the paint colour. Kit and luggage scuffing from bags, helmets, and other items carried into the car also damages the sill paint.
The threshold plate covers the sill at this critical wear zone, taking the abrasion on the chrome plate rather than the paint underneath. Replacing a worn threshold plate is significantly easier and cheaper than respraying the sill.
Fit and installation
Threshold plates fit across the sill at the door opening, typically secured with countersunk screws into the underlying sill structure. The exposed surface is chrome-plated for visual appearance and corrosion resistance; the underside that contacts the painted sill is typically protected to avoid scratching the paint during installation. Installation is a simple direct-fit operation on the standard MGA sill geometry.
Ordering considerations
The threshold plate set is the standard finishing item for the MGA door sill, appropriate for any restoration or for refurbishment of a car where the original plates have worn through, become pitted, or been removed at some point. The plates are fitted as a pair (both sides) for a consistent visual appearance.
For cars being restored to factory specification, ensure any underlying sill paint is fully cured before fitting the plates to prevent the plate's mounting screws or contact surface from marking the new paintwork.