MG MGB

In October 1964 the MGB went from a three-bearing crankshaft to a five-bearing one, and the capacity did not change. It is still 1,798cc, still 80.26 × 88.90mm, so a customer reading “1800” learns nothing at all — they have to date the car. The five-bearing unit is the 18GB, shared with the Austin and Morris 1800, and the change affects the block, crankshaft, main bearings and caps, flywheel and the rear crankshaft oil seal. A three-bearing MGB is a distinct parts proposition. Two other early splits: pushbutton door handles replace the pull type in early 1965, and the rear axle goes from the MGA-derived banjo type to the tube type — GTs in 1967, all cars from 1968. Banjo and tube axles share nothing.

Brakes are constant throughout: Lockheed 10.75in front discs and 10in rear drums, with a servo optional to 1973 and standard after. Suspension is coil and wishbone at the front, live axle on semi-elliptic leaves at the rear, with Armstrong lever-arm dampers at both ends — the front damper doubles as the upper wishbone, and the MGB never had telescopic dampers as standard. The anti-roll bar story runs in three steps: a front bar became standard on roadsters in late 1966, it was deleted for 1975 as a cost saving, reinstated in 1976, and a rear bar became standard in 1977 with revised geometry. A pre-1977 MGB never had a rear bar from the factory.

Rubber bumpers arrive in the second half of 1974, and they bring more than bumpers: the suspension was raised 25mm to meet American headlamp height rules, which changes the front crossmember packing and spring geometry — rubber-bumper and chrome-bumper springs and crossmember setups are not the same. Then 1976 brought an electric radiator fan, the overdrive switch on the gearlever, a remodelled dashboard and a four-spoke wheel. On overdrive: it is Laycock de Normanville in two types, D-type early and LH-type later, both working on third and fourth until February 1977 when they went to fourth only. Worth knowing before you assume: 98 per cent of home-market and non-American export cars had overdrive, against 12 to 27 per cent of North American ones — and plenty of New Zealand cars came from America.