Getting the seat foam right is as important as the cover itself, a correctly shaped foam gives the cover its form and the seat its support, and fitting a new cover over collapsed or incorrect foam produces a disappointing result regardless of the quality of the trim material. The MGB seat foam specification changed several times across the production run, and the distinctions matter. The 1962 to 1968 non-reclining seat used a specific base foam with a flat profile and a dedicated back foam. The 1969-only reclining seat used a different base foam and back foam unique to that single year.
From 1970 to 1973, the seat base foam had a distinctive raised hump at the front. From 1973 onwards, the hump was flattened out and raised sides were added to the seat base, a change clearly visible when comparing the two profiles side by side. Front seat cushion foams are available for all four periods in both left-hand and right-hand versions. Seat back foams are available for non-reclining, early reclining, and later reclining types.
Seat Back Boards
Die-cut seat back boards provide the correct rigid backing behind the foam, available for non-reclining seats (1962 to 1968), the 1969 recliner, and the 1970-onwards recliner. These are cut from automotive millboard to the correct shape for each seat type.
Seat Diaphragm & Webbing
The seat diaphragm, the rubber suspension base within the seat frame, was used from 1962 to approximately 1972. From approximately 1972 onwards, seat webbing replaced the diaphragm. The two can be interchanged, but some re-drilling of attachment holes in the seat frame may be necessary. Calico webbing covers are available to protect the foam base from abrasion against the webbing or diaphragm beneath.
Headrests are available separately in both the D-shaped eared type fitted to cars until September 1976 and the pear or barrel shape fitted from September 1976 onwards. Both styles are offered in vinyl or leather, always matching the seat colour. Even on GTs with nylon seat facings, the headrests were always vinyl-covered. The D-shaped headrest is also available with a perforated vinyl centre section to match the half-perforated seat covers used from 1970.
GT rear seat foam is available as a complete set for owners retrimming the rear bench alongside the front seats.