The quarterlight is the pivoting front vent window that opens for ventilation and frames the forward edge of the door glass aperture, directing a controllable stream of air at the occupants' face level, an important feature on a car without air conditioning. On any car of this age the quarterlights are a common source of draughts and water ingress when the seals, pivots, and glass have deteriorated, and the same assemblies fitted to the contemporary MGB are used on the MGC.
Construction & Change Points
The frame construction changed during production, the original chrome-plated brass extrusions being replaced by brushed stainless steel in April 1972 at car number 279340. At the same time on the GT, the original piano-type hinge was replaced by two small hinges and the toggle catch was lengthened, permitting the window to open slightly further, while the GT rear quarterlights changed from brass-framed to stainless steel from May 1972 at car number 286062, the original Furflex seal used on earlier GTs being difficult to source though the later moulded seal can be used as an alternative. The frame was also modified in 1963 at car number 63863 to incorporate an extra front leg going down inside the door, and the locking handles changed from a curved type to a flat straight type during MkII production, first for the USA, then Canada, then all other markets.
Glass & Assemblies
Quarterlight glass is available in clear and tinted for both body styles, with complete stainless steel assemblies available for the Roadster as a pair. Pivots are available individually in chrome and stainless steel versions for both top and bottom positions, and over time the pivot mechanism becomes stiff from corrosion and lack of lubrication, or loose from wear in the pivot pin and bushes, a stiff pivot making the quarterlight difficult to operate while a loose one allows it to vibrate and rattle at speed. Cracked or chipped glass should be replaced promptly, as aside from the visual defect, damaged glass weakens the assembly's resistance to forced entry.
Seals, Corner Blocks & Fixings
Quarterlight seals cover several distinct interfaces, frame-to-glass, frame-to-door, and rear quarterlight glazing seals all available in the correct left and right hand versions, and deteriorated seals allow water to run down inside the door, pooling at the bottom and accelerating corrosion of the door skin from the inside, so replacing the seals and overhauling the pivot mechanism during any door trim or glazing work is recommended as these items are most easily accessed with the door card removed. Corner blocks are available in three versions covering different production periods, and quarterlight-to-door bolts, repair screws, frame reinforcements, and all associated fixings are available throughout.