Vehicle Description
Development of the MGB started at least as early as 1958 with the
prototype known by its Abingdon codename; MG EX205.[4] In structure
the car was a progressive, modern design in 1962, using a unitary
structure, instead of the traditional body-on-frame construction
used on both the MGA and MG T-types and the MGB's rival, the
Triumph TR series.[5] However, components such as brakes and
suspension were developments of the earlier 1955 MGA, with the
B-Series engine having its origins in 1947. The lightweight design
reduced manufacturing costs while adding to overall vehicle
strength. Wind-up windows were standard, and a comfortable driver's
compartment offered plenty of legroom. A parcel shelf was fitted
behind the seats. The MGB achieved a 0�€"60 mph (97 km/h) time of
just over 11 seconds. The three-bearing 1,798 cc B-Series engine
produced 95 hp (71 kW) at 5,400 rpm �€" upgraded in October 1964 to
a five-bearing crankshaft. From 1975, US-market MGB engines were
de-tuned to meet emission standards, ride height was increased by
an inch (25 mm), and distinctive rubber bumpers were fitted to meet
bumper standards. The MGB was one of the first cars to feature
controlled crumple zones designed to protect the driver and
passenger in a 30 mph (48 km/h) impact with an immovable barrier
(200 ton).[6][7] Nevertheless, the British AA motoring association
has described the car, like many other classic models, as much less
safe than modern cars. The issue received public attention
following a 2013 case in which a driver in a hired 1963 MGB was
killed in a collision with a taxi.[8] A limited production of 2,000
units of the RV8 was produced by Rover in the 1990s. Despite the
similarity in appearance to the roadster, the RV8 had less than 5%
parts interchangeability with the original car. All MGBs (except
the V8 version) used the BMC B-Series engine. This engine was
essentially an enlarged version of that used in the MGA with engine
displacement being increased from 1,622 to 1,798 cc. The earlier
cars used a three-main-bearing crankshaft, 18G-series. In February
1964 positive crank-case breathing was introduced and the engine
prefix changed to 18GA, until October 1964, when a five-bearing
crankshaft design was introduced, the engine prefix became 18GB.
Horsepower was rated at 95 net bhp on both five-main-bearing and
earlier three-bearing cars with peak power coming at 5,400 rpm with
a 6,000 rpm redline. Torque output on the MGB had a peak of 110
lb�...ft (150 N�...m) and fuel consumption was around 25 mpg.[9] US
specification cars saw power fall in 1968 with the introduction of
emission standards and the use of air or smog pumps. In 1971 UK
spec cars still had 95 bhp (71 kW) at 5,500 rpm, with 105 lb�...ft
(142 N�...m) torque at 2,500 rpm. Engine prefixes became 18V and
the SU carburetor needles were changed for reasons of the latest
emission regulations, under ECE15. By 1973 it was 94 bhp (70 kW);
by 1974 it was 87, with 103 lb�...ft (140 N�...m) torque; by 1975
it was 85 with 100 lb�...ft (140 N�...m). Some California
specification cars produced only around 70 hp (52 kW) by the late
1970s. The compression ratio was also reduced from 9:1 to 8:1 on US
spec cars in 1972. All MGBs from 1963 to 1974 used twin 1.5-inch
(38 mm) SU carburetors. US spec cars from 1975 used a single
Stromberg 1.75-inch (44 mm) carburetor mounted on a combination
intake�€"exhaust manifold. This greatly reduced power as well as
created longevity problems as the (adjacent) catalytic converter
tended to crack the intake�€"exhaust manifold. All MGBs used an
SU-built electric fuel pump. All MGBs from 1962 to 1967 used a
four-speed manual gearbox with a non-synchromesh, straight-cut
first gear. Optional overdrive[10] was available. This gearbox was
based on that used in the MGA with some minor upgrades to cope with
the additional output of the larger MGB engine. In 1968 the early
gearbox was replaced by a full synchromesh unit based on the MGC
gearbox. This uni
