The glazing specification changed at several points across the production run, and the correct glass, seals, and fixings depend on the body style, production period, and in some cases the market specification of the car. On the GT, including the MGB GT V8, all glazing is shared with the contemporary four-cylinder GT, with no V8-specific glazing.
Windscreen
The Roadster windscreen is a structural component, the cast aluminium frame comprising two side pillars, a top rail, and a bottom rail forming part of the overall body stiffness, so correct installation with the proper seals and fixings matters for both weatherproofing and structural integrity. The windscreen glass was always laminated.
In March 1966 a change was made to high impact-resistant glass on North American cars, and this type was fitted to Roadsters for all markets from the start of MkII production in late 1967. The windscreen frame was modified for the 1970 model year to accept the new dipping interior mirror mounting, and again from 1976 when a slightly thinner glass was introduced alongside a revised rubber glazing strip. Windscreen assemblies are available in standard and polished frame finishes in clear and tinted glass for three production periods, pre-1969, 1970 to 1975, and 1976 onwards. The GT windscreen used a rubber glazing strip with a four-piece anodised aluminium finisher set, split vertically at the centreline with two joining clips.
On all GTs the windscreen is laminated safety glass set in a rubber surround that perishes over time and should be renewed during any major bodywork, as surround failure causes water ingress and corrosion of the windscreen aperture flange.
Door Glass & Quarterlights
The door drop glass, which lowers into the door cavity, was not changed during Roadster production but went through several changes to channels and regulators in the early years. Drop glass is available in clear and tinted versions for both body styles, the GT door glasses being frameless and taller than the Roadster type. The front quarterlights were originally chrome-plated brass extrusions, changed to brushed stainless steel in April 1972 at car number 279340. Quarterlight glass, seals, pivots, and all associated fixings are covered in detail within the dedicated sub-sections.
Tailgate Glass & Seals
On the GT, the tailgate glass is set in a rubber surround similar to the windscreen, sealing to the tailgate frame, and replacement is straightforward with the tailgate accessible. The tailgate also incorporates the heated rear window element on cars where this was specified, a series of fine resistance wires bonded to the inner glass face that warm the glass to clear condensation. Triplex Sundym tinted glass was introduced on North American GTs from the 1971 model year and became optional on home market models a year later, becoming standard on all GTs from the 1977 model year. Glass seals comprise the rubber surrounds at windscreen and tailgate, the door window weatherstrips, the quarterlight seals, and various trim items at the glass edges, all wear items that should be renewed during major restoration to ensure proper weatherproofing.